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Network Traffic Monitoring

In order to be fully effective, network traffic monitoring software should keep a close eye on not only what is happening within your network, but what is happening on the perimeter of your network as well. In order to give network managers complete visibility over this area of activity, network traffic monitoring software must have deep packet inspection to identify the content of network packets originating from public IP addresses and subnets.

Network traffic monitoring software with this depth of visibility has many practical uses within the network as well. It can be used to troubleshoot network issues, conserve bandwidth, identify threats to the security of the network and enforce acceptable use policies. The monitoring can be done in real time of historically when real-time analysis is insufficient to identify trends or time-sensitive issues when certain network events occur.

LANGuardian is a leader in network traffic monitoring software. It is quick to install, easy to maintain and fully effective at monitoring the traffic on and around the perimeter of your network versatile. To find out more about LANGuardian, read our network traffic monitoring blog posts, contact us with any questions you have, or download a trial of LANGuardian today in order to evaluate our network traffic monitoring software free of charge in your own environment for thirty days.

How To Determine What Ports Are Active On A Server

Active server ports

Active Server Ports

I spent most of last week on the road visiting customers. Many of them were working on projects to reduce the number of physical servers hosted in their data centers. In some cases, they wanted to move the servers to cloud services such as AWS or Azure. In others, they wanted to virtualize the servers locally on platforms such as VMWare ESX.

One of the challenges many network managers have is how to determine what network ports are active on servers and what ports were active in the past. When one device sends traffic to another, the IP address is used to route that traffic to the appropriate place. Once the traffic reaches the right place, the device needs to know which app or service to send the traffic on to. That’s where ports come in. An active server port is one which is ready to accept connections from a clients. Examples include TCP port 80 for HTTP and TCP port 25 for SMTP email.

Network managers need a real time and historical report showing them what ports were in use so that they can update firewall rules and access lists. Many networks now contain trusted systems such as company owned PC’s, but also non trusted systems such as contractor’s laptops. It is vital that you protect servers by only allowing connections on certain ports and from certain networks.

Generating a list of active server ports

While command line utilities such as netstat can give you a real-time view of network connections (both incoming and outgoing), it does not provide historical reporting. Some network ports on a server may only become active when certain applications are used.

Another option is to monitor network traffic going to and from your servers. If the server accepts a connection on a certain port, it will generate network traffic. All you need to do is monitor that traffic using a SPAN, mirror port or TAP, and capture the active port metadata. The metadata will reveal the source IP addresses, port information and the amount of data transferred.

Network traffic analysis systems, which are application aware, can also reveal what applications are running on the server. You may have a web server running over a non standard port like TCP port 8000, for example.

Reporting on active server ports using LANGuardian

Our LANGuardian product can provide a real-time and historical view of what ports are active on your servers. It does this by analyzing network traffic and then extracting application and port information which is stored in a database.

The screenshot below shows a sample report where I focus on a server ( Use the search box at the top of the LANGuardian GUI and enter ports. Select the report Bandwidth :: Ports, Services and Protocols. Enter the IP address of the server you want to query into the Destination IP/Subnet field, select a time range for the report, and then run it. Click on the image below to access a sample report on our online demo.

LANGuardian report showing open ports on a server

The total column in this report shows the amount of data that has been sent or received by the server on each port number for the selected time period. The Server Port (Service) column lists the ports that were active on the server. Clicking on the Total column will also reveal what applications are using the ports. You just need to drill down to the Bandwidth :: Sessions report and check the protocol column. Click on the image below to access a sample report on our online demo.

Server sessions showing port information

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how it can be used to report on what ports your servers are using, do not hesitate to contact us and speak with our technical support team.

Network Security Monitoring Tools Need Traffic For Context

network security monitoring software

What are network security monitoring tools?

Network Security Monitoring is the collection, analysis, and escalation of indications and warnings to detect and respond to intrusions on computer networks. Network security monitoring tools typically have features such as:

  • Network-based threat detection
  • Proactive network queries for security data and/or “hunting” for suspicious behavior
  • Integration with one or more threat feeds
  • Create and automate security alerts

A lot of the development focus in recent years has been in the areas of better threat feeds and web front-ends. We now have network security monitoring tools which can pull threat intelligence from multiple sources and display alerts in fancy dark themed web interfaces. The image below shows a typical output of a modern network security monitoring application.

network security monitoring tool report

Recently, I heard about an interesting LANGuardian use case where a customer used their system to carry out forensics on an event triggered by their network security monitoring tool. While LANGuardian can be used as a network security monitoring tool, this customer had a secondary system to make use of other threat feeds.

Why traffic capture is very important when it comes to network security monitoring.

One of the issues with many network security monitoring tools is that they only generate alerts; often good alerts or “actionable alerts” as some of our customers call them. A typical event will display the source IP address (system that caused the event), destination IP address (system that was targeted), event description, and a priority rating.

However, sometimes you need more than just an alert in order to fix problems on a network. Other pieces of metadata can be just as important as the alert itself. Examples include:

  1. What inbound and outbound network connections were active to the destination IP address at the time the event was triggered?
  2. Any other events associated with the destination IP address?
  3. What DNS queries were associated with the destination IP address?
  4. If the source IP address is on the LAN, is there any unusual activity associated with it (items 1 to 3 above)?

Network traffic metadata is an ideal data source to compliment your network security monitoring tool because it will provide you with extra context, so you can gain a better understanding as to why security events are triggering on your network. It delivers detail without the complexity and costs associated with full packet capture.

Network metadata is typically captured via a SPAN, mirror port or TAP. A common setup is to monitor network traffic at your networks core; where the most interesting traffic converges. Network packets are sent to a deep-packet inspection application which can extract readable information such as filenames, web sites, applications, protocol versions, etc. This information is then stored in a database which can be used for real time or historical analysis.

Using LANGuardian to combine network security monitoring and traffic analysis.

Our LANGuardian product includes both network security monitoring and traffic analysis modules. The image below shows a sample output where we are looking at activity associated with a single IP address. On the left we have traffic and application information, and on the right we have the output of it’s intrusion detection system. Click on the image to access this dashboard on our online demo.

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how it can be used with other network security monitoring tools, do not hesitate to contact us and speak with one of our technical support team.

How to Alert on Rogue DHCP Servers

Detecting rogue DHCP servers using network traffic

Alert on Rogue DHCP Servers Using Network Traffic as a Data Source

Recently a customer came to us with the following query:

We were wondering whether there is a way to setup an alert on LANGuardian if we see any other DHCP servers on the network other than our own – particularly on the range. We have DHCP snooping on all our newer switches, but not on some the older ones. We have used LANGuardian to do this manually with a report – but an email alert would be great.

The ability to detect DHCP servers is a feature that has been in LANGuardian for some time, but more and more customers want alerts if a rogue DHCP server appears on the network.

DHCP is a standard Internet protocol that enables the dynamic configuration of hosts on an Internet Protocol (IP) internetwork. Dynamic Host Configuration Protocol (DHCP) is an extension of the bootstrap protocol (BOOTP). The image on the right depicts the breakdown of a typical DHCP client request.

A DHCP server is a machine that runs a service that can lease out IP addresses and other TCP/IP information to any client that requests it. They are usually managed and controlled by the network administrators.

Rogue DHCP server showing DHCP request

Rogue DHCP Servers & Their Risks

A rogue DHCP server can be defined as one which is not managed by IT. It could be a wireless router added to the network by a user or someone enabling DHCP services on a server.

As clients connect to the network, both the rogue and legal DHCP server will offer them IP addresses as well as a default gateway; DNS servers, WINS servers, and others. If the information provided by the rogue DHCP differs from the real one, clients accepting IP addresses from it may experience network access problems, as well as an inability to reach other hosts because of an incorrect IP network or gateway. IP conflicts can cause problems for existing clients and they may also experience network access problems.

In addition, if a rogue DHCP is set to provide as a default gateway, such as an IP address of a machine controlled by a misbehaving user, it can sniff all the traffic sent by the clients to other networks. This is typically referred to as a man in the middle attack.

Detecting DHCP Servers

One of the easiest ways to detect DHCP servers on your network is to monitor network traffic via a SPAN, mirror port or TAP. Once you have your packet data source, watch out for DHCP offer packets. These are sent by DHCP servers when a client sends out a broadcast packet looking to discover a DHCP server.

The image below shows the output of a DHCP request sequence which was captured using Wireshark. You can use the bootp filter to exclude other packets from the display. This approach is particularly useful for smaller networks where the traffic volumes are low. For larger networks, you may want to consider a dedicated traffic analysis system such as our own LANGuardian.

DHCP offer packet

LANGuardian comes with a set of DHCP reports. To access these, type DHCP into the search bar at the top of the web GUI and select Services :: DHCP Servers. You can filter based on a specific subnet by using the Server report variable on the left hand side. The image below shows an example of the report output. It lists all active DHCP servers for a selected time period. Click on it to access this report on our online demo.

DHCP servers detected using network traffic analysis

Generating Alerts if Rogue DHCP Servers Are Detected.

While running DHCP server reports are useful, most of us do not have the time to do this on a regular basis. Another useful feature of LANGuardian which can help here is the in built alerting engine. For example, I want to generate an alert if a DHCP server is detected within my network range. The steps involved to get this alert setup are:

  1. Log onto your LANGuardian web interface and click on the gear symbol top left. Select Settings
  2. Within settings select Alert rules
  3. Click on Add New Rule.
  4. Assign a name to the rule, like Rogue DHCP Servers
  5. Select the DHCP module from the dropdown
  6. Enter the text server_ip= && message_type=2 as the rule and then save

You may need to change the IP range to match your own network IP ranges. The image below shows the rule definition on my LANGuardian.

A LANGuardian rule to alert on rogue DHCP servers

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how our network traffic monitoring tool can be used to detect rogue DHCP servers, do not hesitate to contact us and speak with our technical support team.

Passive capture of usernames from RADIUS traffic

What is RADIUS?

RADIUS stands for Remote Authentication Dial In User Service. A RADIUS server can support a variety of methods to authenticate a user. When it is provided with the username and original password, given by the user, it can support PPP, PAP or CHAP, UNIX login, and other authentication mechanisms.

Typically, a user login consists of a query (Access-Request) from the NAS to the RADIUS server and a corresponding response (Access-Accept or Access-Reject) from the server. The Access-Request packet contains the username, encrypted password, NAS IP address, and port.

Why the need to capture username from RADIUS traffic?

Many of our customers who provide wireless access on their networks use RADIUS to authenticate users. Active Directory is often used to authenticate wired devices or devices which can be managed and added to the Active Directory domain. However, if you allow unmanaged devices onto your network, like you would in a University, RADIUS is a better choice for user authentication.

A few years ago, we added Active Directory integration to our LANGuardian product as customers wanted to associate network activity to usernames rather than IP addresses. We implemented this by collecting user logon events from domain controllers and storing them locally on LANGuardian where they could be cross referenced by running a report.

Initially, RADIUS integration seemed to be more complicated. As you can deploy the system on different platforms, you never have a standard source of user logon events. However, a customer of ours, an Information Security Manager at a Scottish university, suggested a new way to capture usernames during an onsite meeting. He said that it may be possible to capture usernames directly from network traffic.

They had large wireless networks and wanted usernames so they could save time troubleshooting operations and security issues. Their LANGuardian instance was highlighting user and application issues, but the source was always an IP address. They then had to spend more time working out what user was responsible by manually checking logs.

We took a sample PCAP from their network and used it to build a passive RADIUS username capture module. The image below shows how usernames can be seen within RADIUS.

RADIUS packet showing username which was captured from RADIUS traffic

Passive capture of usernames from RADIUS traffic using LANGuardian

LANGuardian captures traffic from both a SPAN port and other traffic sources. It then uses deep packet inspection techniques to consolidate and correlate the data gathered by the traffic collection engine. In essence, we have a series of application decoders for popular applications like SMB, SQL, Web, and Email. Our latest release includes a decoder for RADIUS traffic.

The image below shows the basics of how our RADIUS traffic decoder works. Firstly, we receive network packets (1) from a SPAN mirror port or TAP (2). The LANGuardian content based recognition engine (CBAR) then detects the CBAR protocol (3) and sends the data to the RADIUS traffic decoder. This decoder extracts relevant metatdata (4) like username, IP address and time/date of logon. RADIUS Accounting needs to be enabled as LANGuardian utilises RADIUS Accounting to retrieve usernames from the traffic.

RADIUS username metadata capture from network traffic

Once you capture usernames with LANGuardian, you can use this data with any LANGuardian report. The first example below shows how you can monitor network traffic to find out who is doing what on the Internet. Click on the image to view the report on our online demo.

RADIUS usernames associated with web activity

In the next example, we show how you can generate an audit trail of file and folder activity (SMB and NFS) with usernames. This can also be used to root out security issues such as SMBv1 use on a network. Click on the image to view the report on our online demo.

SMB metadata capture

If you have any questions about how to analyse RADIUS traffic on your network and extract usernames, or would like to know more about how our network traffic monitoring tool can meet your organization´s requirements, do not hesitate to contact us and speak with one of our helpful technical support team.

Beware of Exposed Ports at Your Networks Edge

More reasons to check inbound traffic on your network

Looking though the latest infosec news this week I spotted two exploits which use similar attack methods.

  • Printers targeted via TCP port 9100 by external clients
  • Poorly configured Ethereum nodes targeted over port 8545

In both cases hosts located outside your network try to connect to devices hosted inside your LAN or cloud environments. The printer exploit is an unusual one. It’s main purpose is to deliver PewDiePie propaganda around the world. PewDiePie is currently the most subscribed to channel on YouTube. Recently it has been in a battle for this position with an Indian company called T-Series.

Over the last couple of days, Twitter users have been posting screenshots of unsolicited printouts from internet-connected printers that say that PewDiePie needs their help. A Twitter user called TheHackerGiraffe has claimed responsibility but had claimed they did this to raise awareness of printers and printer security.

pewdiepie hack

The second inbound exploit attempt has a more sinister background. A cybercriminal group has managed to steal a total of 38,642 Ethereum, worth more than $20,500,000, from clients exposing the unsecured interface on port 8545. The process behind this is simple. External clients scan your network on port 8545, looking for geth clients and stealing their cryptocurrency. Geth is a multipurpose command line tool that runs a full Ethereum node implemented in Go.

How to monitor inbound traffic on your LAN

One quick check you can do to check for port 9100 or 8545 activity is to check if the ports are open on your firewall. While this is not an indication of activity you should consider shutting them down for all external clients.

A better approach is to monitor network traffic going to and from the Internet using a SPAN, mirror port or network TAP. Once a traffic source is established you can use a product like our own LANGuardian to report on what ports and applications are been used.

The image below shows an example of what to look out for. In this case we can see evidence of SMB activity. Ports like 9100 or SMB which uses 445 should not be open for unknown clients. Click on the image below to access this report on our online demo.

Inbound traffic on ports 9100 or 8545

In the next example we are looking at what ports are accepting connections from external clients. Again we can see the activity on TCP port 445. Looking though the results, I also need to check the activity on port 49158. Click on this image to access the report on our online demo.

Inbound TCP ports which are open on firewall

In order to check your firewall configuration and get visibility of traffic at an application level allowed in through your firewall, simply deploy a traffic analysis system such as LANGuardian and configure the sensor SPAN or mirror port correctly.

You can easily use a SPAN port for example to monitor traffic from your  internal network to and from the firewall. A very useful and simple validation of those firewall rules sometimes configured by an external consultant. The video below goes through what is needed to get network traffic analysis in place at your network edge together with the steps to get LANGuardian in place monitoring this traffic.

How to monitor inbound traffic in the cloud

When an infosec alert like the ones mentioned above goes out, the oblivious thing to do is check your on premise data centers for suspicious activity. This is certainly a good starting point. However, don’t forget about your cloud based networks. They may be targeted even more than your on premise networks. Getting visibility in the cloud is not as straightforward as with a more traditional on premise network.

Recently we announced support for AWS VPC Flow Log Analysis and we will also have an option for Azure monitoring shortly. I took a look at reports associated with our AWS estate and sure enough there is evidence of inbound activity on port 9100, see image below. In our case this was blocked. I observed similar activity for inbound connections on 8545.

AWS flow logs showing activity on ports 9100 and 8545

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how our network traffic monitoring tool can meet your organization´s requirements, do not hesitate to contact us and speak with one of our helpful technical support team.

Extracting Metadata From PCAP Files

What our customers want to extract from PCAP files

In my previous blog post on the topic of PCAP file management, I looked at how you can import and export PCAP files from LANGuardian. Since then we had a number of queries come in from customers and website visitors. One in particular caught my eye. It came from a network engineer who had very specific requirements. They have a large PCAP repository and they need a tool to process these files and provide reporting on:

  1.  Identify all the unique IP addresses involved in the PCAP, sources and destinations
  2. Identify the “big talkers” which IP’s account for sending and receiving the most traffic. ideally a list of IP’s, packets sent, and the number of packets received  WITH the ability to sort by # of packets sent or received (that would show the big talkers)
  3. The types of traffic by protocol
  4. I need to have some ability to utilize an AV engine against the traffic. One way to do this with Wireshark is typically via tcpreplay, you set up a “clean system” with IDS enabled then tcpreplay to it suspect packets and watch it’s alarms/logs.

Why can’t you use Wireshark for analyzing PCAP files?

Wireshark is an excellent tool and I use it a lot myself. The most common features I use are the packet analysis and Follow TCP Stream options. What it is not good at is giving you a top level view, a summary of what went on with drill down capability to get to the detail. Another limitation is the ability to cross reference the data in the packets with threat databases or IDS signatures.

Wireshark doesn’t work well with large network capture files (you can turn all packet coloring rules off to increase performance). Some of the most interesting network data can be sourced from a SPAN or mirror port but these data sources will result in large PCAP files.

Identify all the unique IP addresses involved in the PCAP, sources and destinations

Every packet of data in a PCAP file will contain source and destination IP addresses. A modest sized PCAP could contain thousands of addresses so you need a quick and efficient way to capture these and store them in a database.

Wire data analytics is often referred to the process where metadata such as IP addresses is extracted from PCAP files or directly from the network when you monitor network traffic from a SPAN or mirror port. The image below shows a sample of this network inventory type information which LANGuardian can extract from a PCAP file. Click on the image to access this report in our online demo.

IP addresses extracted from PCAP files

Identify the “big talkers” which IP’s account for sending and receiving the most traffic

Some time ago I spoke to a LANGuardian customer who had just purchased the system for a client. They had found us while searching on the Internet for a tool which would “analyze PCAP files that I had collected from a customer’s network that was struggling with VOIP quality issues and massive bandwidth utilization“.

They also reported that “While I read and understand PCAP files fairly well, when it came time to analyze the date and determine who my top talkers are I was at a loss.” This is one of the big problems with tools like Wireshark, sometimes it can be hard to get that summary information. Who are the top talkers on the network.

Our customer installed LANGuardian and within a short period reports that “The LANGuardian software quickly pointed out several computers that were flooding the network with data and a network switch that was faulty. Our customer mitigated those problems and has had great VOIP quality and lower total bandwidth utilization on their LAN and WAN.

The image below shows the output of the LANGuardian Top Talkers by Traffic Volume report. If you click on the demo you can access this report on our online demo.

Top talkers based on traffic volumes. Data extracted from a PCAP file

The types of traffic by protocol

Protocol recognition is the art and science of identifying the applications that are in use on a network and understanding the impact of each application in terms of bandwidth usage, user behavior, security, and compliance.

LANGuardian content-based application recognition (CBAR) approach to application recognition combines a unique deep packet inspection algorithm with detailed understanding of the underlying protocols. Unlike other traffic monitoring technologies such as NetFlow, which analyzes packet headers only, LANGuardian CBAR analyzes entire traffic packets and inspects their content.

By inspecting the packet content in addition to the header, LANGuardian CBAR can see past the port and address information to identify the application and/or protocol that generated the packet. The image below shows the output of the LANGuardian Applications in Use report which shows the top protocols found in a PCAP file ordered by total bandwidth. Click on the image to access this report on our online demo.

Extracting protocol and application data from PCAP files

Ability to utilize an AV engine against the traffic

When I read this requirement first I was confused. How could we replay traffic against an antivirus engine. Most antivirus systems run as a service and may check memory, disk, and other data sources for the presence of malware or viruses. I checked back and what they meant was if we could run the contents of the PCAP files past an IDS or threat database.

In the case of LANGuardian, we have both an IDS and traffic analysis module running in parallel. When you import a PCAP file, the contents is sent to each analysis engine where it is checked for signs of suspicious content. You can also write your own IDS signatures to search for specific text strings within the PCAP files. The video below goes through the process of creating a custom IDS signature to check for the presence of a text string.

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how our network traffic monitoring tool can meet your organization´s requirements, do not hesitate to contact us and speak with a member from our technical support team.

What Traffic Reports To Focus on if You Are Dealing With Google Unusual Traffic Notifications

Why does Google sometimes show unusual traffic messages?

Recently I worked with a number of network managers who downloaded our LANGuardian software to try and find the source of malware on their networks. The issue they faced was that clients were been presented with the message “Our systems have detected unusual traffic – possibly Malware from your computer network” when they tried to access Google services.

You then get a reCAPTCHA. To continue using Google, you have to solve the reCAPTCHA. It’s how Google knows you’re a human, not a robot. After you solve the reCAPTCHA, the message will go away and you can use Google again. The image below shows an example of what is displayed.

Google recaptcha which is displayed if Google google has detected unusual traffic coming from your network

Google closely monitors what network traffic is directed at their infrastructure. If devices on your network seem to be sending automated traffic to Google, you might see “Our systems have detected unusual traffic from your computer network.” Google considers automated traffic to be:

  • Searches from a robot, computer program, automated service, malware (true?) or search scraper
  • Software that sends searches to Google to see how a website or webpage ranks on Google

The main reason behind all of this is that Google does not want any automated traffic which is designed to influence search results.

How can I monitor Google traffic on my network?

All Google traffic will flow in and out of your Internet gateways so this is where you need to capture traffic. Use a SPAN or mirror port to capture a copy of traffic going to and from your firewall. Make sure you capture the data inside your network so you can identify what client is sending unusual traffic.

The image below shows a typical setup if you want to detect any unusual traffic on your network. In this we use our LANGuardian traffic analysis tool to monitor traffic coming from a SPAN\Mirror port on our core switch. LANGuardian is deep-packet inspection software that monitors network and user activity. The core switch is configured to send a copy of all traffic going to and from the firewall to the monitoring port which is also known as a SPAN or mirror port.

Monitoring network traffic using a SPAN or mirror port

What traffic reports do I need to look at?

Our LANGuardian product is available as a 30 day trial. This should give you enough time to get to the root of the problem. Once you have the trial installed there are two key reports to focus on. Use the search bar at the top of the LANGuardian GUI to search for these reports:

  • Top Website Domains with Client IPs (Page Hits)
  • Top Website Domains with Client IPs

In both cases enter Google into the Website Domain report filter on the left. The first report will show the top clients connecting to Google services based on the number of connections. The second report shows the top clients on your network connecting to Google services based on traffic volumes. Unusual traffic would be seen as a client which is establishing thousands of connections in a short time period like one hour. Unusual traffic volumes can be seen as multiple gigabyte levels to Google search or Google API services.

Click on the image below to access our online demo and see what the reports look like.

Two traffic reports to look at if you want to find the source of unusual traffic on your network

If you have any questions about how to monitor traffic on your network using LANGuardian, or would like to know more about how our network traffic monitoring tool can meet your organization´s requirements, do not hesitate to contact us and speak with one of our helpful technical support team.

5 Tips For Monitoring Network Traffic on Your Network

Monitor Network Traffic

Monitoring traffic on your network is important if you want to keep it secure and running efficiently. The information obtained by network traffic monitoring tools can be used in multiple security and IT operational use cases to identify security vulnerabilities, troubleshoot network issues and analyze the impact new applications will have on the network. These 5 tips should help you get the most out of your network traffic monitoring application.

1.    Choose the right data source

Whatever your motive for monitoring network traffic, you have two main data sources to choose from:

  1. Flow data: which can be acquired from layer 3 devices like routers
  2. Packet data: which can be sourced from SPAN, mirror ports or via TAPs

Flow data is great if you are looking for traffic volumes and mapping the journey of a network packet from its origin to its destination. This level of information can help detect unauthorized WAN traffic and utilize network resources and performance. However, flow-based tools for monitoring network traffic lack the detailed data to detect many network security issues or perform true root cause analysis.

Packet data extracted from network packets can help network managers understand how users are implementing/operating applications, track usage on WAN links, and monitor for suspicious malware or other security incidents. Deep packet inspection tools provide 100% visibility over the network by transforming the raw metadata into a readable format and enabling network managers to drill down to the minutest detail.

2.    Pick the correct points on the network to monitor

Naturally with agent-based software, you have to install software on each device you want to monitor. This is not only an expensive way of monitoring network traffic but it creates a significant implementation and maintenance overhead for IT teams. Furthermore, if your objective is to monitor activity on a BYOD or publicly-accessible network, agent-based software will not give you the full picture of user activity because it is impractical (and in some states illegal) to monitor activity on users´ personal devices.

Even with agent-free software, a common mistake many people make when deploying tools to monitor network traffic is that they include too many data sources at the start. There is no need to monitor every network point. Instead you need to pick points where data converges. Examples of this would be Internet gateways, Ethernet ports on WAN routers or VLANs associated with critical servers.

If you are new to getting tools in place to monitor network traffic, I would suggest you start by monitoring your Internet gateway(s). This can be an excellent source of security and operational data. This short video below explains how you can do this with Cisco switches – a similar approach can be applied to other switch vendors.

The image below shows a good approach when it comes to network traffic monitoring for most networks. A SPAN or mirror port is configured at the network core which allows for the capture of any traffic passing through. In my example this would allow me to capture traffic going to and from the Internet as well as traffic associated with important servers.

network diagram showing how you can monitor network traffic

3.    Sometimes real-time data is not enough

The ability to monitor network traffic in real-time is sufficient to achieve many objectives of network traffic monitoring, but sometimes real-time data is not enough. Historical traffic metadata is ideal for network forensics and is just as important if you want to analyze past events, identify trends or compare current network activity with the previous week. For these objectives, it is best to use tools for monitoring network traffic with deep packet inspection.

Some tools for monitoring network traffic choose to age data. This means the further back you go historically, the less detail you get. While this can save on disk space, it is not an ideal solution if you are trying to determine how an intruder managed to overcome your defenses to plant malware on the network. Without accurate and complete data relating to the event, you can be left looking for answers that no longer exist.

It is also a good idea to be aware that some SIEM and network traffic monitoring systems base their pricing on the amount of data you want to store. Keep a watchful eye out for this when you are evaluating solutions. Other appliance-based tools are limited based on the specifications of the system you buy, and an upgrade becomes a replacement appliance which can be expensive. The most flexible option is a network traffic monitoring tool that is software-based and allows you to allocate whatever disk space you think is appropriate.

4.   Associate the data with usernames

Traditional network traffic monitoring tools usually report on activity using IP or MAC addresses. While this is useful information, it can be problematic in DHCP environments if you are trying to find a problematic device. One piece of information that can bring together network activity and devices is usernames. Username association will let you know who is doing what on the network.

user network traffic

5.    Check the flows and packet payloads for suspicious content

Many networks have intrusion detection systems at the edge but very few have this type of technology monitoring internal traffic. All it takes is one rogue mobile or IoT device to compromise a network. Another issue I often see are firewalls allowing  suspicious traffic through where a rule was misconfigured.

The image below shows an example of this: someone created a rule to allow traffic inbound on TCP 5901 (VLC remote desktop sharing), but they did not limit it to one source and destination. The source addresses in this case appear to be registered in China and connections from this country would not be expected to connect to this network.

Detecting IoT devices with network traffic monitoring


Not all tools for monitoring network traffic are the same. Generally they can be broken down into two types – flow-based tools and deep packet inspection tools. Within these two types you have the choice of tools that use/don´t use software agents, tools that store/don´t store historical data, and tools with intrusion detection systems that monitor network traffic within the network as well as at the network edge.

  • Choose flow based analysis tools if you want to get traffic volumes and IP addresses associated with WAN or other layer 3 links
  • Choose packet analysis tools if you need traffic volumes, IP addresses and more detail to investigate security or operational issues.

If you would like to discuss any of the points raised in this article, do not hesitate to contact us.

Video – Tracking Mobiles Devices on Your Network

Sample mobile devices

Tracking Mobile Devices on Your Network

In this video we look at how you can monitor mobile devices on your network using LANGuardian. LANGuardian is deep-packet inspection software that monitors network, device, and user activity. It uses network traffic as a data source and is typically connected to a SPAN or mirror port at the core of a network.

The video also has a section on how you can choose the best point on your network to monitor traffic associated with mobile devices. A traffic analysis approach does not require the installation of client or agent software on your wireless or mobile devices.

As the video shows, every device (fixed and mobile) and user on a network leaves a traffic trail. This traffic trail contains very useful information and context but due to the large volumes on traffic on network these days and the inherent complexity of traffic, this trail is not easy to read and interpret. Our LANGuardian network traffic analysis engine tries to do the ‘heavy lifting’ extracting the application specific metadata and making it useful and usable for organizations of sizes, even SMEs with limited resources and time.

network traffic metadata

The screenshot above is a very good example of the useful detail buried deep in normal network traffic. This packet payload shows an iPhone making a HTTP request, our LANGuardian DPI engine looks inside the packets extracting and storing crucial information like the IP address, operating system and device type. Vendor agnostic, always ‘on’, network traffic is a very useful data source on any network. You just have to ‘tap into it’ to get immediate internal visibility of devices, users and activity.

Network Traffic Metadata – Four Recent Customer Use Cases

SIEM Tools

Network Traffic Metadata – Four recent customer use cases

The rising popularity of network traffic metadata is because it’s in the sweet spot between full packet capture like Wireshark and PCAPs on one hand and NetFlow on the other, which lacks detail and drill down. Drill down, granularity, context, and continuous internal visibility are now absolutely critical for organizations of all sizes including SMEs.

Historically, network traffic analysis based technologies (mostly full packet capture) were seen as too complex and expensive for SMEs and only ever seen on Enterprise networks. Application centric metadata has now made internal visibility a reality for all organizations.

Use Case 1: Monitoring Web Activity Over HTTPS

The opening packets of a TLS/HTTPS session are not encrypted and are sent in clear text. However, the NetFort DPI (Deep Packet Inspection) engine has the ability to conduct an IDP (Initial Data Packet) analysis on these clear text packets, extract the SNI (Server Name Indication) field sent by the client, and the certificate that the server presents.

This allows LANGuardian to report on the domain being accessed, the client and server IPs, port numbers, as well at other attributes of the connection such as the protocol used (SSL 1.0, 2.0 or TLS 1.0 1.2 etc), ciphers used or attributes of the server certificate (SHA1 or SHA256 etc). A similar technique works with Google QUIC encrypted UDP protocol.

Click on the image below to see how this report works on our online demo

Traffic Metadata with encryption protocols and cipher sessions

Use Case 2: Alert on Rogue DNS Servers

LANGuardian includes a DNS metadata decoder which monitors DNS traffic, decodes and logs all DNS replies, and enables the ability to go back and review all resolutions clients are receiving. As a result, it generates an inventory of DNS servers by Geo IP location.

DNS Lookups as network events

Use Case 3: Contractors’ iPhone Copying Data

The LANGuardian’s web client, user agent module generates every web client packet payload and records useful metadata such as source IP address, device and operating system information.

iPhone copying data

Metadata also results in a 400:1 data reduction over full packet capture in a granular but cost-effective data retention, ideal for forensics and investigations. LANGuardian includes a Google like search utility for all user activity retained in the built in database. This information was recently used to investigate the activity of a contractor on an medium enterprise network who had used an iPhone to access and copy internal data.

Use Case 4: Monitor File and Internet Access For a Single User.

LANGuardian’ s network traffic analysis engine also includes decoders for all ‘unstructured data’ activity, including Windows (SMB), UNIX and (NFS) file shares and even MS SQL databases. This results in an inventory of such systems on the internal network and an audit trail of all activity by IP, MAC address and user name.

Using our search facility, it is possible to achieve a consolidated view of all internal and Internet network activity by user name for any time period. It is also possible to configure alerts for certain file activity, including file or folder deletes. No agents or clients required, therefore network metadata is an excellent non-intrusive option for monitoring network user activity.

User traffic metadata dashboard

Visit our live system HERE to see more examples of the unparalleled levels of visibility you can easily achieve on your network by using traffic metadata.

Employees Leaving? Need an Audit Trail?

Getting an audit trail when employees leave

Users Leaving? How to get an audit trail

Network users come and go. When new employees start we create sign on accounts and assign any relevant permissions. When employees leave we typically transfer their data over to someone else and disable any logon accounts.

During this transition period, an audit trail can be an invaluable resource. Sometimes users think they are doing everyone a favor by deleting what they think is old data or they move data around without telling anyone. In other cases, users may copy large volumes of data from the network with the intention of using it in their new job.

There are two main ways of getting an audit trail of user activity on your network. You can either install client\agent software on every network device or you can monitor network traffic inside your network. Client or agent software can be problematic as users can disable it or it may not be feasible to install it on personal devices.

Network traffic analysis is the most independent with no requirement for any client software or server logs. You just need to capture network traffic at the correct points and extract the relevant metadata. It is an ideal data source for network visibility, security, and compliance.

Monitoring Network Traffic

Network traffic analysis tools use deep packet inspection technologies to extract certain metadata from network traffic. Traffic is typically captured at the core of a network using a SPAN, mirror port, TAP or packet broker. Metadata can be something like a filename or a SQL query. When captured and stored this metadata can be then used to build an audit trail of user activity.

The image to the right shows a typical traffic capturing setup where traffic going to and from important servers is copied to a monitoring or SPAN port. This is a method of passive monitoring and because it is not in line it does not interfere with client and server communications.

It does not matter if users use wired or wireless devices, their traffic will be seen as it passes through the core switch.

Monitoring network traffic using a SPAN or mirror port

Focusing on an individual user for a specific time period

Recently we heard from a customer who had an issue when an employee was leaving. This employee moved, renamed and deleted some files off network shares. Using their LANGuardian, the network manager was able to get an audit trail of file and folder activity to find out what had been changed. It was then just a matter of putting everything back in its original location which saved the IT department a lot of time trying to figure out what files needed to be restored.

The image below shows a sample of the LANGuardian file activity monitoring reports. Data in this report is acquired by analyzing the network traffic associated with the SMB or NFS protocols.  Here we can see where user Leo deleted a profit and loss database together with the exact date and time when this action was seen.

user file activity

It may also be worth looking at other user metadata when suspicious file activity is observed. The image below from a LANGuardian system shows that this user accessed some customer and sales data (1) and at the same time, data transfers were associated with Dropbox (2).

Cloud-based storage systems like Dropbox can be used to copy data out of a network and you may want to set up alerts if activity like this is detected on your network. We will follow up with another post showing how you can set this up with LANGuardian, just subscribe to our blog to get updates.

Click on the image below to access the user forensics section of our online demo.

Network user forensics screenshot

Detecting Inbound RDP Activity From External Clients

Monitoring RDP traffic

What is RDP? (Remote Desktop Protocol)

RDP is a proprietary protocol developed by Microsoft. It provides a user with a graphical interface to connect to another computer over a network connection. It has been a native OS feature since Windows XP.

Most of the time, RDP is used for legitimate remote administration: when companies outsource IT, or remote admins have to access a server or a network users machine, they most commonly use RDP to connect to it.

Risks Associated With RDP

One of the main risks associated with RDP comes when you allow external clients access to your network. The RDP protocol typically uses TCP port 3389. Attackers often find instances of this port open by scanning infrastructure exposed to the Internet and using brute force to access open ports. Automated tools and the Shodan search engine help them find systems configured for RDP access online.

Once on a system attackers can disable endpoint protection, establish a foothold in the organization and more. Once this happens, no endpoint security solution can save you. They might download and install low-level system tweaking software and use it to disable or reconfigure anti-malware software on the machine, Sophos researchers explained in a post on RDP and ransomware distribution. RDP connections can also be used to transfer data out of a network.

Recently I spoke to a network manager who was running a trial of our LANGuardian product. Their business need was around getting visibility inside their network and not for RDP specifically. Shortly after they started to monitor network traffic they noticed a lot of inbound RDP connections from many different countries.

When their firewall was checked they found what they described as a legacy rule to allow third party vendor access. Nobody checked this and as they had no visibility inside their network they had no idea systems running RDP were exposed to external clients. They implemented a quick fix which was to block inbound RDP connection attempts.

In July this year, the SamSam group infected some 7,000 Windows PCs and 1,900 servers at LabCorp with ransomware via a brute force attack on an RDP server. In another incident this year, Hancock Health was forced to pay over $50,000 in ransom to regain access to critical data that criminals had encrypted after breaking into its network via a hospital server running RDP services.

How to Detect RDP Activity

One quick check you can do to check for RDP activity is to see if TCP port 3389 is open on your firewall. While this is not an indication of activity you should consider shutting it down for all external clients. It is also possible to run RDP over a different port number so focusing on TCP port 3389 alone is not enough.

A better approach is to monitor network traffic going to and from the Internet using a SPAN, mirror port or network TAP. Once a traffic source is established you can use a product like our own LANGuardian to detect if RDP is in use on your network. You will need a system which is application aware as RDP can run over any network port so looking for activity on TCP port 3389 alone is not sufficient.

The image below shows an example of what to look out for. In this case we can see evidence of RDP activity.  Clicking on the traffic total allows us to drill down to investigate further.

Remote Desktop Protocol Detected

Further drilldown reveals that the RDP activity is originating from a client in China and it is connecting to a host located inside the network. An immediate action would be to block that IP address on the firewall if a connection to the network from China is not expected. Blocking port 3389 would also be recommended in this case.

RDP connections from external host

Getting an alert if an external client connects to your network using RDP

While running reports are useful when it comes to forensics on a past event, most network and security managers want to be notified immediately if someone external connects to their network using RDP. Follow these steps to get alerting setup on your LANGuardian:

  1. Select the report Applications in Use and enter all subnets in use on your network preceded with the ! symbol into the source report filter.
  2. Select Remote Desktop Protocol from the Protocol drop down
  3. Run report and then click on the Actions option and choose Save As. Enter a report name and then save.
Generating RDP alerts

The final step is to use this custom report to trigger an alert if RDP is detected. Click on gear symbol top right then Settings / Email and alerts configuration.

Select Add New List and then give it a name, add email addresses, select custom report and tick the last 3 boxes as per the image below.

Setting up RDP alerts

We host everything in the cloud. Should we worry about RDP?

Absolutely. It does not matter where you host your servers. If RDP is left open on a server it increases your attack vector. Verify that all cloud-based virtual machine instances with public IPs have no open RDP ports, especially port 3389, unless there is a valid business reason to keep open RDP ports. Place any system with an open RDP port behind a firewall and require users to use a virtual private network (VPN) to access that system.

Recently we announced support in LANGuardian for AWS VPC Flow Logs. This new feature provides for visibility inside your AWS estate. I just checked our cloud based LANGuardian and I can see lots of inbound RDP connections from all over the world. The image below shows a report from this system. I had to mask some of the data as it is from our live environment. In our case we can see that all connections are rejected.

Inbound RDP connections to servers hosted in AWS

What Should You do About RDP?

  1. Audit your network for systems that use RDP for remote communication. Disable the service if unneeded or install available patches. Users may need to work with their technology vendors to confirm that patches will not affect system processes.
  2. Limit access: Consider changing the default port of TCP 3389, using virtual networking/VLANs/etc. to limit access to critical systems via RDP. Block inbound RDP access from the Internet, it is far too risky to leave open.
  3. Make sure systems that have RDP enabled use network level authentication with complex passwords and all activity is monitored closely.
  4. Monitor endpoints. Make sure you have visibility on your network and you know who is connection to what. This is especially true for inbound connections from hosts on the Internet.
  5. If you have a requirement for remote desktop access from outside your network, consider using a commercial product with encryption and more advanced user account options.

Deriving Hostname Annotation From Network Traffic

Derive Hostname Annotation from network traffic

What is Hostname Annotation?

In computer networking hostname annotation is typically referred to the way a text based name is assigned to an IP address. This makes it easier for users to remember what they need to connect to. This concept is nothing new, we use a similar approach when it comes to phone numbers. Our phone contains a database of names and their corresponding numbers and most of us just remember the name part.

A hostname may be a domain name like or it could be the name assigned to your laptop. In corporate environments computer names usually follow a naming convention so when you see the hostname you will also instantly know who the computer was assigned to.

Hostnames are also very useful when it comes to network incident response. Many logs on devices such as firewalls and servers will have IP address information but then you are left with the question “what hostname does this IP address represent?” Knowing this usually speeds up the process to get to the root cause of the problem.

How to capture hostnames

Gathering a comprehensive database of hostnames requires multiple data sources. Local machine names could be gathered from DHCP logs and Internet hostnames can sometimes be gathered by doing a reverse DNS lookup.

Away from logs there is a rich data source for hostnames on all networks. If you monitor network traffic at strategic locations you can use deep packet inspection to extract the hostnames. Network traffic can be captured using a SPAN, mirror port or network TAP. Capturing hostnames this way is passive and you don’t need to enable any logging on any network device. Strategic locations to capture network traffic would include

  • Local DNS servers
  • DHCP servers
  • Internet gateways

A look at hostnames captured from network traffic

The following screenshots were taken from a LANGuardian system that I have in my lab. It uses network traffic as a data source and captures the hostname information using a series of application aware analysis engines. While you can capture hostname information manually from traffic using tools like Wireshark, LANGuardian delivers automatic hostname annotation capture which is always on.

1. DNS Traffic

In this first example we can see the output of the LANGuardian DNS lookup report. As you can see DNS traffic contains a wealth of hostname information. Click on the image to access the report in our online demo.

2. DHCP Requests

Hostnames are transmitted when a client (wired or wireless) requests an IP address from a DHCP server. In my example I am using LANGuardian to build an inventory of all wired and wireless devices that connect. Click on the image to access the report in our online demo.

Hostnames captured by analyzing DHCP requests

3. HTTP Headers

HTTP header fields are components of the header section of request and response messages in the Hypertext Transfer Protocol (HTTP). They define the operating parameters of an HTTP transaction. When users want to browse a website the hostname of the site can be found in the HTTP header generated by their browser. The image below shows how this information can then be used to build an Internet domain style report. Click on the image to access the report in our online demo.

Web hostnames extracted from HTTP headers

4. SSL/TLS Certificates

An SSL/TLS certificate is like a driver’s license, it serves two functions. It grants permissions to use encrypted communication via Public Key Infrastructure, and also authenticates the identity of the certificate’s holder. This identity information will contain a hostname and it is transmitted in clear text during the cert negotiation process.

The image below shows an example of this hostname annotation which LANGuardian extracted from network traffic captured at the perimeter of a network. Click on the image to access the report in our online demo.

SSL\TLS hostnames extracted from network traffic

For more information on how LANGuardian works, check out this page. You can also download a trial version of LANGuardian if you want to test how hostname annotations can be quickly captures from network traffic.

Looking to Download VAST to Root Out SMBv1? Try This Alternative

What is SMBv1?

SMB operates as an application-layer network protocol mainly used for providing shared access to files, printers, and serial ports and miscellaneous communications between nodes on a network. Microsoft has implemented three versions of SMB over the years; SMBv2 and SMBv3 are much more secure than SMBv1.

Many Ransomware and Cryptocurrency mining malware variants spread from computer to computer by exploiting critical vulnerabilities in Microsoft’s implementation of SMB version 1. Microsoft recently announced that their security visualization tool (VAST) can report on SMBv1 activity. This is in a response to demand from network and security managers who want to find out if SMBv1 is still active on their networks. However, before you download VAST let’s take a look at the alternatives.

How to root out SMBv1 from your network. Should you download VAST or use an alternative?

There are two primary ways to detect SMBv1 activity on your network. You can either use log files or you can analyze the network traffic going to and from your file servers. Log files will require changes on your file servers, you will need to increase the logging to capture SMBv1 events. Traffic analysis is passive and will not have any performance or storage impact on your servers but you do need to setup a SPAN or mirror port.

Using log files to detect SMBv1

At the end of March 2018 , Microsoft unveiled Project VAST or the Visual Auditing Security Tool (VAST). It uses Windows event logs as a data source and Azure Log Analytics to filter on EventID 3000 for each and every time that a client attempts to access the server using SMB1. You do need to enable auditing on every file server using the command below and this approach does not work for non Windows devices like NAS units.

$computers = Get-Content “c:\SMB_computers.txt” foreach ($computer in $computers) {Invoke-Command -ComputerName $computer -ScriptBlock {set-smbserverconfiguration -auditsmb1Access $true -Force}}

The image below shows an example of these events. You could manually check for these events if you only have a single file server but you will be better off to use a separate application to do this job if you have multiple servers.

SMBv1 EventID 3000. Download VAST if you need a tool to filter these events in a report

Using network traffic analysis to detect SMBv1

A more passive approach to detecting SMBv1 involves the use of network traffic analysis. To get a data source you need to monitor network traffic going to and from any file server or network attached storage device. This is easy to setup as all managed switches have a feature called SPAN ports or port mirroring.

The image below shows a typical setup. A copy of the traffic passing through the core switch is sent to the monitoring port. You need to connect your traffic analysis application\device to this port and it checks the file share traffic for SMBv1 activity.

Capturing SMBv1 activity from network traffic

If you host your file servers on virtual platforms such as VMWare ESX you don’t need the SPAN or mirror port, you can monitor the traffic within the virtual environment by setting up a special virtual port group. We have a couple of videos on this page which describe the setup process.

The image below shows a sample report from our LANGuardian system which can be used to detect SMBv1 activity. It also integrates with Active Directory so you can also see the associated username.

Make sure you look at alternatives before you download VAST or similar log analysis tools. Will it be easier to monitor the traffic than make changes on your servers? Do you have any file sharing devices that don’t have logging capabilities?

MSP Managing Your Network? Make Sure You Have Independent Visibility

MSP did not identify hole in firewall

Using MSP services? Make sure you have independent monitoring in place

A third party such as a managed services provider (MSP) is most often an information technology (IT) services provider that manages and assumes responsibility for providing a defined set of services to its clients either proactively or as the MSP (not the client) determines that services are needed. The main drivers for the adoption of MSPs is the desire to improve operations and cut expenses.

Even years ago before the term MSP was popular, many organizations used external contractors and services to install and configure critical security equipment like firewalls.  Firewalls configurations and rules can be very complex, how do you check them? Make sure they are correct? One option is to look at the traffic and activity inside the firewall.

Recently I worked on an interesting problem with a client who was using a MSP to manage their firewall. They were happy with this arrangement as the MSP did not report any problems and they had nothing independent to highlight any issues.

Case study: Unreported hole in firewall

One thing this client needed outside of the MSP services was a tool to monitor network traffic . They needed a high level view of bandwidth use at their network edge and they contacted us. A trial of our LANGuardian product was deployed, the ability to monitor web traffic and capture associated metadata is one of its many features.

When we started to look at the data captured we noticed something very strange with inbound traffic patterns. We define inbound traffic as a connection were the source IP address is outside the network perimeter (outside the firewall). Over 98% of traffic was associated with LDAP traffic over UDP 389 to one of their domain controllers. Traffic over UDP 389 is typically connection-less LDAP (CLDAP), a variant of LDAP that uses the User Datagram Protocol (UDP) for transport.

Our LANGuardian product has an application recognition engine and so it reported the activity correctly as LDAP. If you are using a tool which uses port numbers (port 80, etc…) to report on activity you may miss things like LDAP.

Drilling down on this traffic we could see connections from China, Russia and many other countries. Our determination was that the domain controller was been used as part of an amplification based DDoS botnet. Infosec attackers are now abusing exposed LDAP servers to amplify DDoS attacks.

We immediately put in a change request to the MSP to block UDP port 389 on the firewall. As you can see from the image below the inbound traffic dropped significantly once the firewall change was implemented.

Connectionless LDAP (CLDAP), a variant of LDAP that uses the User Datagram Protocol (UDP) for transport

The big lesson here was the need to have something in place to provide visibility of what was happening on the network. The hole in their firewall was an old NAT rule that was long since outdated. However, their MSP did not pick up on this activity. It needed an independent monitoring tool which could show what was happening on their network.

Finding out what is going in and out of your network with LANGuardian.

LANGuardian comes with a selection of reports which can be customized to filter on certain activity. For this use case we selected the Applications in Use report and we used a specific source and destination IP address filter. You can also use the Report Variables feature to define what subnets are in use inside your network. Follow these steps to get these custom reports setup on your LANGuardian.

1. Create report variables to define what subnets exist on your LAN. If you use private address ranges then you can use the exact same setup as the image below. The only difference between the External and Internal variable is the use of the ! character. This character denotes NOT so any subnet outside of this is not on your LAN.

2. Click on All Reports and select the Applications in Use report. Click the drop down next to Source IP / Subnet on the left and select the External report variable. Click the drop down next to Destination IP / Subnet on the left and select the Internal report variable.

Click on Run Report. You should get an output like the one shown below. In my case I will need to drill down on that SMB activity as I would not expect to see file sharing traffic where the client (source) is outside my network.

3. You can then save this as a custom report by clicking on Actions \ Save As or create a line graph by selecting the Trend Report option.

4. Finally, repeat the steps to show what applications clients are using on the Internet by selecting Internal as a source and External as the destination within the Applications in Use report.

MAC Address Tracker: Generating a Network Inventory Database Using Network Traffic Analysis

MAC Address Tracker Screenshot

Why do we need to track MAC addresses?

A media access control address (MAC address) of a device is a unique identifier assigned to a network interface controller (NIC) for communications at the data link layer of a network segment. As they are unique, they are used by network devices such as switches to maintain an inventory of what is connected to what switch port.

The concept of a network inventory has been around for a long time, it is one of the fundamentals of networking. Devices cannot exchange data unless they know who to share it with. However, a lot of this inventory information is hidden behind the scenes, buried in MAC tables on switches and distributed across multiple devices.

Many compliance standards such as GDPR now require network managers to maintain a list of what is active on their networks. However, it is good practice to maintain a list of what is connected to your network. If you get hit with something like Ransomware, you will need to act fast and track down what is connected to your network quickly.

Where can you capture MAC address information?

The easiest way to capture MAC addresses is to monitor network traffic via a SPAN, mirror port or TAP. This will give you access to network packets and each packet will contain MAC addresses. You need to be careful about where you capture this information. If you monitor traffic on the wrong side of a routing device like a firewall or network router, you may find that all traffic is associated with the firewall\router MAC address.

An ideal location for capturing MAC addresses is the network core where traffic from clients and servers converges. The image below shows a sample output from our own LANGuardian system which captures metadata like MAC addresses from network traffic.

Server logs and flow data are not good data sources when it comes to capturing data for a MAC address tracker. Logs and flow records focus more on IP addresses which can move from device to device on networks that use DHCP. The image below shows a typical flow record with date, time, IP and port information.

Network Flow Data

Common use cases for a MAC address tracker

In the past MAC address capturing was typically done using packet analysis tools such as Wireshark. While this is useful for troubleshooting isolated issues, it is not very scalable when it comes to tracking all network device activity.

Recently one of our customers had an issue during a very busy and critical time of the day, the switches were reporting ‘Broadcast storm detected’ and had applied filters as a defense mechanism. This resulted in connectivity issues on their network. As they had an inventory of MAC addresses and associated broadcast traffic, they located the rogue network device quickly. In their case it was a faulty IP phone and normal network operations resumed after it was shutdown.

A use case like the one above shows that the need to track devices on network is important. Common use cases that we come across include:

  1. Generating a list of network devices for compliance standards such as GDPR
  2. Detect faulty network equipment which may be responsible for broadcast traffic storms
  3. Quickly locate problematic devices in the event of a malware outbreak such as Ransomware
  4. See the corresponding MAC address associated with copyright violations where clients are using applications like BitTorrent
  5. Capture additional metadata for your existing network monitor or SIEM application
  6. Track specific application like web traffic by MAC address

The video below shows how you can use a network traffic analysis application to find the host-name or MAC addresses of devices connected to your network.

How to detect SMBv1 scanning and SMBv1 established connections

Detect SMBv1 Scanning and SMNv1 active or established connections

Detect SMBv1 scanning and active or established connections

Detecting SMBv1 activity is a subject we have covered previously. It has been used as an attack vector for Ransomware and Cryptocurrency Mining. Microsoft has advised all customers to stop using SMBv1. SMBv2 was introduced with Windows Vista in 2006 and the latest version is SMB 3.1.1 which was introduced with Windows 10 and Windows Server 2016. At a minimum, you should make sure that all Windows systems on your network have the MS17-010 patch applied.

One of the easiest ways to detect SMBv1 activity on your network is to monitor network traffic going to and from your file servers. You can do this by setting up a SPAN, mirror port or use a network TAP. This will give you a copy of all activity going to and from the servers.

Once you have your data source which is sometimes referred to as wire data, you can use a network traffic analysis application like our own LANGuardian to extract the file and folder information from the network packets.

SMBv1 scanning vs established connections

There are two types of activity to watch out for when it comes to SMBv1 activity. Clients which are trying to use SMBv1 and clients which are successfully connecting to servers using the SMBv1 protocol. The latter is more serious as you actually have servers on your network supporting and using SMBv1. Microsoft recommends immediately removing this old and vulnerable file sharing protocol from all networks. The recent WannaCry and Petya ransomware attacks for example actually used the same SMBv1 exploit to replicate through networks.

  1. SMBv1 connection attempts or SMBv1 scanning. This is where a client sends an SMB request to a server and the version flag is set to v1. The server may or may not accept the connection request.
  2. SMBv1 connections. This is where a client and server have established a connection using SMBv1. You need to root out these first. At a minimum make sure the client and server are fully patched.

The video below shows an example of what to look out for once you get network traffic monitoring in place. A trial version of LANGuardian can be used to perform a quick audit if you do not have something in place already.

Video: Detect SMBv1 scanning & established connections

Why use network traffic as a data source to detect SMBv1?

By monitoring network traffic on your network you can get visibility of file and folder activity without the need for agents or log files. Agents can be difficult to deploy and scale and they become one other thing to update and manage. Log files do not always have the answer as they only report about local server issues.

Wire data which can be extracted from network traffic is instant and way more flexible than log data. This wire data can provide an audit trail of all network-based file and folder activity. Capture information such as:

  • List of IP addresses and host names which connect to network shares
  • Associated usernames so you know who did what
  • See how much bandwidth is associated with users accessing files and folders
  • Build an inventory of actions such as delete, read or rename including date stamp

Report on Traffic Between a Certain Source IP and Destination IP Address

Get traffic between a certain source IP and dest IP along with the time of the connections

Reporting on traffic between network devices

Recently one of our customers got in contact with this simple query.

I am looking to find out if it’s possible to get traffic between a certain source IP and destination IP along with the time of the connections.

They needed a historical report so there was no point in launching a tool like Wireshark as it would not report on the historical activity. As they have LANGuardian installed they have 24/7 visibility throughout their network. By utilizing a SPAN, mirror port or network TAP at strategic locations you can monitor network traffic you can spot abnormal behavioral patterns as they occur. But, critically for this use case, the LANGuardian retains rich network traffic metadata very cost effectively for long periods.

Network traffic reports

The image below shows a sample output from a LANGuardian IP search. Click on the image to access our demo where you can drill down on sample data. The element (1) shows the traffic between a certain source IP and destination IP which is what the customer was looking for. LANGuardian also shows what applications (2) were in use by this network device, suspicious events (3) triggered by the IP. In this case we can see that there was a Malware infection as well as some BitTorrent activity.

IP Search results

The image below shows the exact level of detail that the customer was looking for. We can see the traffic between a certain source IP and destination IP along with the time of the connections. The logged in user can also be shown as LANGuardian can integrate with Active Directory to capture usernames. Country flags are shown which is useful for forensics, this is made possible by matching IP addresses against a GeoIP database.

For this incident the customer wanted to look back 3 months. This is easy to select in LANGuardian by picking a specific time range from within the reports.

IP flow time selection from within reports
IP flows between IP addresses

Other uses for network traffic analysis

Network traffic analysis was traditionally seen as an operational tool. Something to report bandwidth usage on WAN and Internet links. However, it is an excellent data source for network security use cases including:

  • Internal and east-west traffic analysis
  • Ransomware detection
  • Automated threat hunting
  • Passive detection of weak ciphers and vulnerable SSL certificates
  • Report on insecure protocol use such as FTP and Telnet
  • Root out network devices scanning your internal networks

By monitoring network traffic on your network you can get visibility as to what is happening without the need for agents or log files. Agents can be difficult to deploy and scale and they become one other thing to update and manage. Log files do not always have the answer as they only report about local server issues. Wire data which can be extracted from network traffic, is instant and way more flexible than log data. It can provide high-fidelity user and application evidence to enhance your evolving security operations center (SOC).

The easiest way to root out SMBV1 on an Enterprise network

Root out SMBV1 from network

Just over 2 weeks ago, we received an inquiry from a large US multinational in the financial sector. They had a very specific requirement, ‘we want to know how much SMBv1 is still in use on our network and start the cleanup’. They had tried just turning it off and waiting for the calls to see who complained but they came and that didn’t work. So basically, they want to get a list of all file share servers accepting SMBV1 connection requests and ‘root it out’.

Makes sense, it is an old vulnerable protocol and recent attacks like Wannacry have demonstrated that it is common sense to ensure it is not in use. It also critical to prep and get as much visibility as possible into the servers still supporting it, and the clients using or depending on it before just disabling it and potentially have a serious impact on the business.

This organisation has a large and complex network, over 50k users and 12 data centres. As they have also acquired several other companies in their space which is not unusual, the network, software and applications are complex and diverse. Making any global change, even a simple upgrade across such a complex network of this size is not a trivial task, and of course, if it is not broken, still supporting the business, why risk it?

We arranged a webex and our demo focussed on this very specific use case. Every device, user and application on the network automatically leaves a trail, a traffic trail. There is no need to turn it ON, to enable logging or install a client. If they are active on the network they leave a trail. LANGuardian ‘sniffs’ this trail, usually via a tap, SPAN or port mirror and using its deep packet inspection engine, extracts application specific metadata for the most critical applications. It also enriches the metadata with usernames extracted using WMI from the logs of the domain controllers. We support a number of ‘critical’ applications, web, SQL, SMTP, BitTorrent, DNS, DHCP and SMB.  With SMB, for example, we extract information such as the client and server IP address, file and folder names and action.

One of the advantages of capturing data ‘off the wire’ is that one has the option or flexibility on selecting the specific details or data to look out for and store and report on demand. The initial SMB client-server negotiation, for example, includes the actual version the client requests and is looking for the server to support and communicate over. So, in the case of SMBV1 the client sends an SMBV1 connection attempt and then if the server supports it, it sends back an SMBV1 connection established. Luckily for us, we supported analysis down to this level, and could instantly show during the demo, all clients on the network initiating a SMBV1 connection request and the servers responding:

Network user SMBv1 actions

Using our report filters to query the database, one can get very specific and list only the servers on any part of the network responding to SMB1 connection requests with success and establishing a SMBV1 connection:

An example of SMBv1 connections on a network

All good so far, this covers the use case required, we have the level of granular detail. The final and most critical step is implementation, critical for such a large network. The system is very easy to use and requires minimum training, so we are good there. LANGuardian can be downloaded and deployed on standard server hardware or VMware. The download and installation, the configuration on the physical or virtual device requires less than 30 minutes, not bad.

The final and crucial step, especially for the network of this size and complexity is sensor placement, how do I see the ‘SMB traffic trail’ or all traffic to and from all file share servers on the network with the minimum number of sensors? Are all the servers in one VLAN and can I just mirror that VLAN for example? Or can I approach it from the client perspective and mirror the point or points in that data centre all clients connect in from? Where are all my file shares? I need to see all traffic to/from all file share servers in order to extract the SMB version information required.

To be investigated….to be continued.

How to Detect Cryptocurrency Mining Activity on Your Network

Detect cryptocurrency mining on your network using network traffic analysis

What is Cryptocurrency Mining?

Bitcoin or Cryptocurrency mining is the process by which Cryptocurrency transactions are verified and added to the public ledger, known as the block chain, and also the means through which new bitcoin are released. Anyone with access to the internet and suitable hardware can participate in mining.

The mining process involves compiling recent transactions into blocks and trying to solve a computationally difficult puzzle.  The participant who first solves the puzzle gets to place the next block on the block chain and claim the rewards.  The rewards, which incentivize mining, are both the transaction fees associated with the transactions compiled in the block as well as newly released bitcoin.

Cryptocurrency mining is painstaking, expensive, and only sporadically rewarding. Mining is competitive and today can only be done profitably with the latest ASICs.  When using CPUs, GPUs, or even the older ASICs, the cost of energy consumption is greater than the revenue generated.

Away from using specialized hardware, the most common way to mine cryptocurrency on standard hardware is to install Crypto mining client software and leave it running in the background. Cyber criminals can also use your computer to mine Cryptocurrencies by hosting Cryptocurrency mining hijacker on websites. If you visit the site without adequate virus protection your browser and CPU will be hijacked by the website operators.

Recently a piece of Malware called PowerGhost Malware has been spreading across corporate networks infecting both servers and workstations to illegally mining the crypt-currency and Perform DDoS Attacks.

In this case, attackers using file-less malware techniques to maintain the persistence which is then used to bypass the antivirus detection and leverage the corporate vulnerabilities using known exploits such as Eternalblue.

PowerGhost is unique for two reasons: firstly, it focuses on attacking corporate networks and secondly, it is file-less. This permits the miner to be able to cling to the servers and workstations of victims without being noticed. PowerGhost’s reign of terror has just began, and so far, reports of attacks have been seen Turkey, India, Brazil, and Colombia.

What are the risks associated with Cryptocurrency Mining?

Only those with specialized, high-powered machinery are able to profitably extract bitcoins nowadays. While mining is still technically possible for anyone, those with under-powered setups will find more money is spent on electricity than is generated through mining. If you have clients on your network running crypto mining software then it is costing your business money.

Many cyber criminals now favor anonymous Cryptocurrencies, with Monero being the most prominent. Cryptocurrencies are popular as they are both secure, private and difficult to trace. Servers are often targeted and since many of them are not updated or patched on a regular basis, attackers have a bigger chance of success.

Recently more than 526,000 Windows hosts, mostly Windows servers, have been infected by a Monero miner known as Smominru, according to researchers at Proofpoint. It spreads using the EternalBlue exploit (CVE-2017-0144) which targeted the SMBv1 protocol.

Cryptocurrency mining malware like this covertly mines for coins using the victim’s GPU horsepower without them knowing about it. It has potential for longer-term gains. When a computer is infected many people will fail to notice fans spinning up, or computers under higher load or just plain old not responding. A lot of those people may just pass it off as “one of those things my computer does.”

How to detect Cryptocurrency mining activity on your network

When it comes to detecting Cryptocurrency mining, you need to be looking at multiple data sources.

  1. Analysis of all DNS client traffic
  2. Use IDS (Intrusion detection software) to detect specific text strings\patterns in network packets
  3. Monitor all IRC communications on your network

DNS query logs can be very useful when it comes to detecting suspicious activity or for use in follow up forensics. Searching DNS queries for text strings like bitcoin or crypto can be used to identify clients running crypto mining software. You can get DNS query information from DNS server logs or if you monitor network traffic going to and from your DNS servers.

Intrusion detection software typically uses pattern matching techniques to spot suspicious activity on a network. Applications such as Snort can be used to detect Crypto mining activity. You just need to make sure you install a well maintained IDS signature set such as those provided by EmergingThreats.

Internet Relay Chat (IRC) is an application layer protocol that facilitates communication in the form of text. Some Crypto miners use IRC but can be detected if they try an use IRC on a nonstandard port, IRC typically uses TCP port 6667.

Using LANGuardian to detect Cryptocurrency mining activity

Our own LANGuardian product uses a combination of network traffic analysis and IDS to provide visibility, context and alerts as to what is happening on a network. The following set of screen shots show how LANGuardian can be used to detect Crypto mining activity on a network. The primary data source would be a SPAN or mirror port which is monitoring all traffic going to or from the Internet. It is also advisable to monitor network traffic going to and from your DNS servers as this can also be used to detect Crypto mining activity. The video below shows how to use LANGuardian to detect Cryptocurrency mining on a network.

The follow image shows the output of a LANGuardian Network Events report which shows Crypto mining activity. The first event is associated with a Windows based (W32) Crypto mining client.  The second event is associated with a client visiting a compromised website that is hosting a Cryptocurrency mining hijacker. The third event in the report is reporting that something is using IRC on a non standard port. This may not be associated with Crypto mining but it is worth investigating.

Cryptocurrency mining IDS Snort events

The next image shows what IP addresses are associated with this activity. LANGuardian also includes an Active Directory module so you can drill-down to see what users are associated with this activity. In this example we can see that the Crypto mining is associated with a single client within the network and it is communicating with external systems hosted in the Netherlands and France.

IDS Drilldown

Next we take a look at the DNS activity associated with this client. If we filter on any domains containing the word coin we find that this client is also looking up numerous Bitcoin related sites. You can configure alerts on LANGuardian if you want to be notified about this activity. Alerts can be delivered as an email or as SYSLOG which can be then used to block the client via a firewall or NAC device.

DNS lookups associated with Crypto Mining activity

As I mentioned previously, you need to continuously monitor network traffic to have a reliable way to detect Crypto mining activity on your network. You can quickly get a data source in place by setting up a SPAN or mirror port to get a copy of all network traffic going to or from your Internet gateway. Once this is in place you can extend the monitoring to include traffic associated with your DNS servers. The video below goes through the process of getting network traffic monitoring in place.

How to monitor Internet traffic using a SPAN or mirror port

Find out if there is any Crypto mining activity on your network with LANGuardian. 30 day trial

Use the deep packet inspection engine of LANGuardian to report on Cryptocurrency mining use on your network. Real time and historical reports available. No need to install any agents or client software.

  • Captures web traffic via SPAN\Mirror port or TAP.
  • Integration with Active Directory so you can see who is doing what on your network.
  • Passive monitoring so no proxy, agents or client software required.
  • Supports monitoring of direct and proxy based web traffic.
  • Built in IDS based on Snort. IDS rule-sets are automatically updated hourly
  • GeoIP matching allows you to see the countries websites or clients are located in.

All analysis is done passively using network traffic analysis and you will see results within minutes.

How to detect devices on your network running telnet services

Detecting Telnet Enabled Devices

Telnet. One of the oldest network protocols

Telnet is a protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. Telnet was developed in 1969 and it is still widely used today for configuring network devices.

Telnet typically uses Transmission Control Protocol (TCP) port 23, but traffic can be directed to a wide range of TCP ports such as 80, 8080, etc…. This is important when it comes to detecting Telnet on your network, you cannot just go off looking for devices which are listening on TCP port 23.

Why worry about Telnet?

Because Telnet is an unencrypted protocol, session traffic will reveal command line interface (CLI) command sequences appropriate for the make and model of the device. CLI strings may reveal login procedures, presentation of user credentials, commands to display boot or running configuration, copying files and creation or destruction of GRE tunnels, etc…

A recent cyber briefing from the UK based National Cyber Security Centre (NCSC) recommends that you check your network for any devices running unencrypted management protocols such as:

  • Telnet
  • Hypertext Transport Protocol (HTTP, port 80)
  • Simple Network Management Protocol (SNMP, ports 161/162)
  • Cisco Smart Install (SMI port 4786)

If these services are in use the NCSC recommends the following:

  • Do not allow unencrypted (i.e. plaintext) management protocols (e.g. Telnet) to enter an organisation from the Internet. When encrypted protocols such as SSH, HTTPS, or TLS are not possible, management activities from outside the organisation should be done through an encrypted Virtual Private Network (VPN) where both ends are mutually authenticated.
  • Do not allow Internet access to the management interface of any network device. The best practice is to block Internet-sourced access to the device management interface and restrict device management to an internal trusted and whitelisted host or LAN. If access to the management interface cannot be restricted to an internal trusted network, restrict remote management access via encrypted VPN capability where both ends are mutually authenticated. Whitelist the network or host from which the VPN connection is allowed, and deny all others.
  • Disable legacy unencrypted protocols such as Telnet and SNMPv1 or v2c. Where possible, use modern encrypted protocols such as SSH and SNMPv3. Harden the encrypted protocols based on current best security practice. The NCSC and Department of Homeland Security (DHS) strongly advise owners and operators to retire and replace legacy devices that cannot be configured to use SNMP V3.
  • Immediately change default passwords and enforce a strong password policy. Do not reuse the same password across multiple devices. Each device should have a unique password. Where possible, avoid legacy password-based authentication, and implement two-factor authentication based on public-private keys.

Using network traffic analysis to detect Telnet activity

As I mentioned previously, Telnet normally runs over TCP port 23. However, you can configure Telnet to run over any port and so you cannot just watch out for network traffic running on TCP port 23. You must be able to monitor all traffic and pick out the Telnet traffic by using some form of application detection.

Wireshark is one of the most popular traffic analysis tools and has the capability to detect Telnet traffic as it has access to packet payloads which can be used for application identification. Flow based tools (NetFlow, SFlow) are not suitable for detecting Telnet activity as they are not application aware. Wireshark is fine for low network traffic volumes or if you have a PCAP file that you want to analyze.

If you want to get continous monitoring in place then you need to look at setting up a data source such as a SPAN, mirror port or network TAP. Once you have a data source then you need a commercial network traffic analysis system in place like our own LANGuardian. It has an application recognition engine which can report on any Telnet activity no matter what port it is running over.

Using LANGuardian to detect Telnet activity on your network

LANGuardian uses Content-Based Application Recognition (CBAR) to identify what applications are running on your network. With support for hundreds of the most common applications and protocols, and a unique deep packet inspection algorithm, CBAR delivers greater accuracy and fewer false positives than other approaches to application recognition.

Typically you monitor network traffic at your network core where a lot of the most interesting traffic passes through. You then apply a filter so that you only show Telnet traffic.

The image to the right shows how you can use the LANGuardian Applications in Use report filter to focus in on Telnet activity. This can then be saved as a custom report if you want to add it to a dashboard or get an alert if Telnet activity is detected on your network.

Telnet application filter

A sample output of this Applications in Use report is shown below. Here we can see that some Telnet activity has been detected.

Telnet applicaton detected

Drilling down on this Telnet traffic then reveals that Telnet services are active on two seperate ports on a single server as you can see in the image below. LANGuardian can also alert you if a new server port becomes active which is useful for watching out for new activations of Telnet services on your network.

Telnet sessions

You can download a 30 day trial of LANGuardian from here and use it to detect any device running Telnet services on your network. You do not need any logs or client software. Just setup a SPAN or mirror port and you can passively monitor activity at your network edge and east west traffic moving within your network.

How to detect weak SSL/TLS encryption on your network

SSL/TLS encryption

Weak SSL/TLS encryption. Why worry?

A Google search for “GDPR countdown clock” yielded 18,900 results for me this morning so probably the last thing we need to consider is another countdown clock, but here is one for PCI compliance anyway.

The clock highlights 30 June 2018,  an important deadline for online security and network Administrators; a date from which older versions of TLS and all SSL should be confined to history for PCI compliant networks. From 30 June 2018, to be compliant with PCI DSS 3.2, SSL and “early versions” of TLS protocol should be eliminated from use (with some exceptions for POS terminals). This is because PCI requires the use of “strong encryption” and known weakness in all SSL, some TLS versions and some cipher suites mean they fail the ‘strong encryption’ standard.

“Early TLS” is defined as anything before TLS 1.1; however TLS 1.1 is also vulnerable as it allows use of bad ciphers; so TLS 1.2 is a better choice. Along with this version change, the ciphers that are used by SSL/TLS need to be carefully managed too. The ciphers and the SSL/TLS protocol versions are separate, but not completely independent of each other.

Even if you don’t care about PCI compliance, this is important for all networks running SSL/TLS; that includes your own networks, partner or client networks, that interact with your infrastructure. GDPR regulations (article 31) require use of “state of the art” technical and organisational measures to ensure security. While the GDPR language lacks specifics, we can look to PCI 3.2 and NIST guidelines (800-52 Rev 1) which strongly recommend use of TLS1.2 only, to know that SSL, TLS1.0 and TLS1.1 are not state of the art, and so fail the GDPR test. The NIST draft for 800-52 Rev 2 explicitly prohibits use of TLS 1.1.

What’s the problem, SSL provides encryption doesn’t it?

Since the mid 1990’s, SSL/TLS encryption has underpinned much of online security and is the defacto choice for encrypting our web based online shopping and payment transactions. SSL/TLS keeps our transactions private and unaltered. However, researchers and attackers have identified and published weaknesses in the aging versions of the protocols, from SSL2.0, SSL3.0, TLS1.0 and TLS1.1. and in the ciphers that they use. There are three sources of weakness here to be aware of:

  1. Some weaknesses are in the protocol implementation itself, for example Heartbleed exploited a read buffer overflow in OpenSSL’s implementation of in the heartbeat extension. This allowed attacking clients to read private key information from the server.
  2. Other weaknesses are in the ciphers supported SSL/TLS. For example, increased computation along with the increased volumes of data being transferred, mean that 3DES cipher can be compromised in about 1 hour, using the Sweet 32 attacks. RC4 can also be compromised by brute force attacks. These weaker ciphers are supported by all versions of SSL/TLS up to version 1.2. However, newer. stronger ciphers such as AES are only supported by newer versions of SSL/TLS. So, use new version of TLS to enable use of stronger ciphers.
  3. Weakness in the protocol itself

Even if properly implemented, according to the spec, with good ciphers, TLS1.1 is still vulnerable. The PRF (pseudorandom function) is based on broken cryptographic hashes MD5 or SHA1 and its use of ciphers in CBC mode is insecure.

There are no available fixes for these weakness, so the only avenue to remain secure is to use the newer more robust versions.

TLS1.3, the newest, most secure version of TLS resolves the known weakness with the protocol, prohibits use of weak ciphers and has a much shorter setup time. TLS1.3 was in draft form when PCI 3.2 was adopted, so it isn’t mentioned in the PCI 3.2 document (TLS1.3 was formally adopted in March 2018. Mandating use of TLS1.3 at this stage could lead to interoperability problems).

Using Network Monitoring for SSL/TLS analysis

There are various techniques for identifying the SSL/TLS versions and ciphers that servers will support, such as nmap or just running Openssl from the command line. However, this requires that periodic checks are carried, the full inventory is always known, and you have access to scan the network. The PCI Security Standards Council emphasise the important of ensuring adherence to standards at all times and not just once per year to close audit requirements!

Continuous adherence is just good business and security practice and essentially points to continuous monitoring, rather than scheduled pen testing efforts. If you monitor network traffic within your network and perform packet analysis at session startup time, it’s possible to view the SSl/TLS versions and cipher used, as well as the certificates used on encrypted protocols (excluding TLS 1.3) .

You can do this without any access to the servers (i.e you can do it from the client or partner network) and without terminating any of the SSL/TLS sessions (i.e you don’t have to use man in the middle devices). This is possible as the opening salvos in SSL/TLS session establishment happen in the clear. The protocol negotiation, cipher choice and certificate exchange are all readable. Add to this the Server Name Indication (SNI) extension and a packet monitoring application can extract a lot of useful information about the nature of encrypted sessions on the network.

LANGuardian 14.4.1 includes features that are useful for monitoring the status of SSL/TLS on your network.

NetFort LANGuardian is deep-packet inspection software that monitors network and user activity passively via a SPAN\Mirror port or TAP. Here are a couple of use cases which cover how it can be used to detect the use of weak SSL/TLS encryption on your network.

The first is an inventory of SSL/TLS servers. Built from passive traffic analysis, this shows every SSL/TLS server, that has generated traffic on the network. The server can be internal or external (e.g a HTTPS website). The inventory report for each server shows some details of the server certificate, with expiry date and signature algorithm. It also shows the SSL/TLS protocol versions that the server has used to communicate with clients. Issues are highlighted in red, such as expired certificates or weak certificate signature algorithms, such as SHA1. A set of filters help identify conditions, such as use of SHA1 and help identify servers that need configuration or updates.

Filters for reporting on SSL/TLS Sever Inventory

Filters for reporting on SSL/TLS Sever Inventory

Report on a single SSL server, showing expired certificate, weak protocol used, weak SHA1 algorithm

Report on a single SSL server, showing expired certificate, weak protocol used, weak SHA1 algorithm

The other feature is a report on all the SSL/TLS sessions that have occurred on the network. This report (and its drilldowns), identifies all clients and servers that use SSL/TLS encryption, identifying the version of SSL/TLS used and the cipher that is used. Filters can be used to focus on versions of SSL/TLS, identify where SSL3.0 is used for example, or identify where any communication occurs that does not use TLS1.2.

Report showing use of weak SSL/TLS versions

Report showing use of weak SSL/TLS versions

Report drilldown showing cipher used by weak SSL3.0 session

Report drilldown showing cipher used by weak SSL3.0 session

A filter is also provided for the ciphers that are used. Ciphers suites have a specific naming scheme, which identity various attributes of the cipher used, viz:


For example, the cipher TLS_RSA_WITH_AES_128_CBC_SHA

is for use with TLS, using RSA for key exchange, AES 128 bit encryption, with SHA digests.

Report showing use of 3DES cipher

Report showing use of 3DES cipher

Filter support for SSL/TLS Versions and Ciphers

Filter support for SSL/TLS Versions and Ciphers

The list of supported ciphers for various versions of SSL/TLS is extensive (many hundreds) and there’s a balance between security and interoperability to consider when choosing which ciphers should be supported. Recommendations generally are to avoid RC4 and 3DES.

Continuous Network Monitoring is a useful tool for ensuring your network is operating to whatever standards or compliance regulations the you are required to adhere. Without using man in the middle decryption devices, it is possible to learn about the activity on your network.

Video Guide: How to detect weak SSL/TLS encryption on your network

You can download a 30 day trial of LANGuardian from here and use it to detect the use of weak SSL/TLS encryption on your network. You do not need any logs or client software. Just setup a SPAN or mirror port and you can passively monitor activity at your network edge and horizontal traffic moving within your network.

How to detect new server ports in use on your network

network servers

What is a server?

In client-server processes that use Transmission Control Protocol/Internet Protocol (TCP/IP) or User Datagram Protocol (UDP), the client initiates communication with a server through one of the many well-known ports. In computer networking, a port is an endpoint of communication in an operating system. While the term is also used for physical devices, in software it is a logical construct that identifies a specific process or a type of network service. For example, HTTP traffic typically uses TCP port 80.

What makes a server is that it is the one that accepts a connection from a client. Typically, this port is left open or running so that clients can connect at any time. It is good security policy to restrict the number of ports which are open on a server. Each open port is a way to gain access to that server. In recent times several Ransomware variants spread around networks by exploiting a vulnerability in SMBv1. Infected clients searched for any host with TCP port 445 active and then tried to communicate using the SMBv1 protocol. The image below shows the handshake that makes up a TCP connection request.

TCP three way handshake associated with server ports

Why worry about new server ports?

As I mentioned previously, opening new ports on a server increases that servers attack surface. Keeping the attack surface as small as possible is a basic security measure. New ports become active if you install new software or if you enable a new service on the server. Enabling something such as RDP (remote desktop protocol) can compromise the entire server and provides a way for data to be transferred off.

For important servers on your network you should have an inventory of what applications or services are running so that changes can be detected. You can do this by constantly polling the server on every port number or monitor network traffic going to and from the server. The polling method can be problematic as you will need to constantly bombard the server with connection requests and you may miss something if the application or service was only active for a short time.

If compliance standards such as GDPR are a concern then server monitoring is not just a nice to have, it becomes mandatory. You must maintain an inventory of who is connecting to what if you store sensitive or personal data.

Detecting new server ports by monitoring network traffic

If you monitor network traffic going to and from your important servers you can build up an inventory of what ports are open without the need to interact with the servers. One way to do this is to use a SPAN or mirror port to get a copy of the network traffic going to and from your servers. You would then need a network traffic analysis tool such as LANGuardian to process this data and extract the relevant metadata from the network packets. The image below shows an example of what would be required. The four servers can be monitored via a single SPAN or mirror port.

network diagram showing how you can monitor network traffic

Detecting new server ports with LANGuardian

Once you have your SPAN or mirror port in place and you have a LANGuardian installed monitoring the network traffic you can start to build up an inventory of new server ports. Type “server ports” into the search field at the top of the LANGuardian web interface and select “Network Events (New Server Ports)“. Pick a date range and then see if any new server ports became active during the selected time period. The image below shows a sample of the report output.

LANGuardian Network Events (New Server Ports) report

The report contains a number of fields

  1. Sensor: LANGuardian can process traffic from multiple network points via remote sensors. The sensor field shows which sensor detected activity on the new server port.
  2. Server address: The network device which is accepting client requests.
  3. Port: Which port the server is listening on. Some ports will be labelled.
  4. When detected: The date and time when communication was first detected.
  5. Server reply: This is section of the servers reply to a client. In some cases it is human readable in others it is just a binary string of random characters.

The video below shows an example of this report in action.

How To Detect Unauthorised DNS Servers On Your Network

Detecting unauthorized DNS servers to prevent DNS poisoning

Why worry about unauthorised DNS servers?

DNS remains a vital part of computer networking. The foundation of DNS was laid in 1983 by Paul ­Mockapetris, then at the University of Southern California, in the days of ­ARPAnet, the U.S. Defense Department research project that linked computers at a small number of universities and research institutions and ultimately led to the Internet. The system is designed to work like a telephone company’s 411 service: given a name, it looks up the numbers that will lead to the bearer of that name.

DNS was never designed as a very secure protocol and it is popular target for attackers. There are two ways DNS can be hacked: by using protocol attacks (attacks based on how DNS is actually working) or by using server attacks (attacks based on the bugs or flaws of the programs or machines running DNS services).

One of the more recent protocol attacks was the

In both of these cases the attackers change your DNS server from (Google) for example to one of their own DNS servers. Most of your DNS queries will be handled correctly and you will get correct IP addresses. However, for certain site like banking the attackers will direct you to a mocked up website which looks like a valid banking one. You logon details are captured once you start to interact with the site and these are then used to steal your money.

Detecting unauthorised DNS server use with LANGuardian

Our LANGuardian product includes both a DNS traffic decoder and an number of alerting features which you can use to track down unauthorised DNS server use. The image below shows an example of the DNS traffic decoder. Here we can see how LANGuardian can build up an inventory of all DNS servers and client queries to them.

A LANGuardian report showing unauthorised DNS server use

Having a DNS audit trail like this will also give you the data you need to investigate other DNS issues such as cache poisoning.

How to generate alerts if a device uses an unauthorised DNS server

LANGuardian includes a customizable alerting engine where you can define whitelists of valid servers and get alerts if users try an access others. For the purposes of this example we are going to create a DNS whitelist containing these servers:

  • (hosted internally on network)
  • (google1)
  • (google2)

We then use the LANGuardian alerts configuration option to create a DNS alerting rule which would trigger if queries to other servers are detected. The screenshot below shows an example of this.

Unauthorised DNS servers alert configuration

Once the rule is saved it will look like this on the LANGuardian alerts list.

LANGuardian DNS Alert Rule

Once the unauthorised DNS server alert is triggered, LANGuardian will capture certain DNS metadata like source and destination IP addresses, country where DNS server is registered and the domain names that were queried. The image below shows an example of what the alerts look like.

A list of unauthorised servers detected on the network using network traffic analysis

These alerts can also be exported as SYSLOG so that they can be processed by a blocking device such as a firewall or NAC (Network Access Control) system.

How to monitor DNS traffic

One of the best ways to monitor DNS traffic is to port mirror traffic going to and from your local DNS servers and all Internet traffic. Monitoring Internet traffic is crucial so that you can pick up on devices using external DNS servers so it is really easy to monitor network traffic on your network. Most managed switches support SPAN or mirror ports. If you have a switch that does not have any traffic monitoring options there are many alternatives for SPAN ports. The video below shows the steps needed to monitor Internet traffic and you should extend this to also monitor local DNS servers.

Find Out What DNS Servers Are In Use On Your Network

Use the deep packet inspection engine of LANGuardian to report on what DNS servers are in use on your network. Real time and historical reports available. No need to install any agents or client software.

  • See what DNS servers are in use
  • Generate alerts if  a network device uses an unauthorised DNS server
  • Capture DNS metadata so you can troubleshoot DNS issues and perform forensics on past events.

All analysis is done passively using network traffic analysis and you will see results within minutes.

Tracking Down New Devices After The Holiday Season

Tracking wireless devices on network

New Devices = New Year Challenges

As 2017 draws to a close I would like to take this opportunity to wish all my business and Infosec contacts a Happy Christmas and best wishes for the new year. It is also the season for exchanging gifts and the top of many peoples list is a new phone, tablet or some other IoT gadget. It is amazing what you can get for so little now. I just watched a video about an Android powered smartwatch that comes with a SIM slot, camera, touchscreen, access to Play Store plus many other features and you get all this for $12.

The challenge that these devices brings is that they may end up on corporate networks. No big deal you may say but all it takes is for one compromised system to bring down your network with a malware infection. The portability is the problem, users walk past your firewall with their shiny new device and suddenly you have a problem inside your network.

Another issue is the potential bandwith grab that new devices bring. Many will need updates and as soon as they get on a network with lots of bandwidth they start downloading updates. Some of these can be over 2GB in size which can swamp WAN or Internet connections.

How can you detect new devices on your network?

One of the best ways to detect new devices on your network is to monitor network traffic going to and from a number of key points including:

  1. Internet gateway
  2. Internal interfaces of proxy servers
  3. DHCP queries
  4. DNS queries
  5. Network interfaces going to WAN routers

One of the easiest ways to monitor network traffic is to use a SPAN, mirror port or TAP. These allow you to get a full copy of network traffic as it passes through a switch. The main thing to remember is that you don’t need to monitor every port on your network, just focus on the ones I have listed above.

Once you have a traffic source in place you then need to extract certain information from the network packets which will allow you to report on new network devices. For the purposes of this blog I am going to use our own LANGuardian system and it can extract device metadata from the packets. The video below details the steps neccessary to monitor Internet traffic and you can extend this to include other network points.

Monitoring Internet Traffic. Proxy & Direct

One of the richest sources of data when it comes to monitoring new devices is Internet traffic. Most wired and wireless devices try an access external services to download updates or to send and receive data to cloud services. Buried within this data will be certain pieces of metadata which can reveal what devices are on your network.

The image below shows an example of metadata captured from Internet traffic which is then used to build up an inventory of what devices are connecting to your network.

Monitoring DHCP Requests

New devices connecting to your network will normally send out a DHCP request so that it can get an IP address which it then uses to communicate. If you monitor these DHCP requests you can start to build up an inventory of what devices are connecting to your network. The screen shot below shows an example of what you should be capturing. Here you can see the device MAC addresses with associated hostname and IP address. An alert can be triggered on LANGuardian if the MAC address is new so you know when a new device connects to your network.

DHCP Requests

Monitoring DNS Queries

Once you start to build an inventory of what is connecting to your network, you should also try and capture some associated data. A good example would be to capture all DNS queries that devices on your network are sending. These queries can reveal a lot about what the devices are doing and what sort of applications they are running. In the example below we can see that there is a device active on our network and it is running cloud apps like WhatsApp and GMail and it is running the Township game.

Monitoring network interfaces going to WAN routers

As I mentioned previously, wireless\IoT devices can consume large volumes of bandwidth. Businesses can be impacted if users in remote sites start complaining that the “network is slow” and all it takes is for one device update to swamp a link. Make sure you are monitoring what applications are using your bandwidth.

An easy way to do this is to monitor the network interfaces on your WAN routers with a product like LANGuardian. It can also associated network activity with usernames so you know who is doing what on your network. A sample of this username integration is shown in the image below.

Top network users

Find Out What Devices Are Connecting To Your Network

Use the deep packet inspection engine of LANGuardian to report on what devices are connecting to your network. Real time and historical reports available. No need to install any agents or client software.

  • See what devices are connecting to your network
  • Generate alerts if a new device connects
  • Capture associated metadata for forensics

All analysis is done passively using network traffic analysis and you will see results within minutes.

How to Passively Detect VPN Clients on Your Network

How to detect the presence of VPN clients

Why worry about VPN clients?

VPNs have been around for a long time. A VPN extends a private network across a public network, and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. Applications running across the VPN may therefore benefit from the functionality, security, and management of the private network.

If you use public WiFi networks such as those found in airports and cafes then it is recommended that you use a VPN service. A VPN will ensure that all of your communication is encrypted.

However, there are times when VPN activity is suspicious and/or bad. I see an increasing amount of VPN actvity on college\school networks. In most cases end users are using a VPN to get around a web filter or use a blocked application such as Bittorrent. A VPN will also punch a hole in your firewall and it may become a route for nasties such as Ransomware.

“A VPN client will punch a hole through your firewall”

Common uses for VPN clients


  1. Site to site connectivity where a branch office can connect to HQ via the Internet
  2. Allows remote workers to connect to HQ
  3. Encrypts your data when you are on a public WiFi network


  1. Bypass web filters (some may not see this as bad)
  2. Allows you to run applications which are blocked
  3. Create a hole in a Firewall which may become the source of a Malware infection
  4. Can be used for data exfiltration

How to detect VPN clients on your network

VPN clients can be difficult to detect as they typically use a port such as 443 over UDP or TCP which is normally open on a firewall. However, there are a number of things to watch out for. First we need to understand how the most common VPN clients work.

Most VPN clients come as a software pack which include the actual VPN software and a database of VPN servers. The idea is that everything you need is included when you install so you don’t need to access a specifc website to connect to anything. If you did it would be easy to block access to these websites. This makes it hard to detect VPN clients if you are looking at reports from something like a web filter.

Once you select a VPN server, an encrypted connection is created between your client and the VPN server. All of your Internet bound activity is then routed through this VPN connection. If you want to browse a website for example, the VPN server connects to the website and sends the text\images\media back to you via your encrypted connection. This is what makes them secure, someone ‘sniffing’ your local traffic can’t see what you are accessing.

How VPN works

In summary, a VPN client makes a direct connection to a VPN server and this server then does the job of accessing what service\application your requested. This differs from users connecting to websites or applications directly. For example I may go and visit YouTube using a web browser. When I type in my computer will go and resolve this name to an IP address using DNS. Computers use IP addresses to connect, not human readable names.

In order to detect VPN clients on a network, we need to watch out for any client sessions where there is client to server connections with no DNS resolutions. To do this you need to monitor network traffic going to and from your Internet gateway and you also need to monitor DNS traffic hitting your DNS servers if you host them locally.

Detecting VPN Clients

  1. Monitor Internet traffic
  2. Monitor DNS queries
  3. Watch out for client connections to external hosts with no name resolution

What you need to watch out for is any sessions to external IP addresses which have no hostnames associated with the server. If the connection is over TCP or UDP port 443 then you are probably looking at VPN client activity. The image below shows an example of what to watch out for if you want to detect VPN clients. The first client listed is connecting directly to an IP address as no hostname is shown. The other connections are to Googlevideo which are part of the YouTube service.

Report showing a VPN client connecting to an external VPN server

Check out the video below to learn more about how you can use our LANGuardian product to detect VPN clients.

Do you really need ‘Artificial Intelligence’ for actionable alerts

Alert image

Using Traffic Analysis as a Data Source

As we have mentioned numerous times in our blogs, Network Traffic Analysis or (DPI) Deep Packet Inspection is a very flexible technology. It can be used for many use cases including continuous monitoring of user and device activity, reporting, forensics, analytics and of course troubleshooting of everyday  problems. One of the benefits of using a DPI engine to analyse network traffic flows, is the rich application specific detail and context, metadata that can be extracted and presented in real time or stored for forensics. Data ideal for many IT security and operational use cases.

DPI can sometimes be seen as a ‘complex and expensive technology’ only suitable for large enterprise, but not with the latest engines as found in the NetFort LANGuardian. The basic principle of the LANGuardian engine is to get the engine to do all the ‘heavy lifting’, reassembly, analysis, alerting thus making it very easy to use and read, ideal for all skill levels across organisations of all sizes with minimum training.

Actionable Alerts That Our Customers Requested

Recently we have been asked by our customers to generate real time alerts on various network and user activities that are critical to them. Examples, in the customers own words include:

  • US Manufacturing company
    • ‘Alert if a user or device generates more than x GB of data over a given time?’
    • ‘Alert if certain file types are detected (e.g. mkv files)? ‘
  • Large EU University
    • ‘Alert when a machine on our network is maliciously scanning 100,000’s of IP addresses across
      the globe. ‘
  • EU Online retail company
    • ‘Any internal ip address making a connection to an external ip where the connection (TCP/UDP) was not preceded by a DNS query that returned the external ip’
  • EU Government organisation
    • ‘Alert on any web accesses not via the proxy server’
  • US City Council
    • ‘I’m trying to figure out the syntax for a rule to detect when the BitTorrent protocol is detected’
    • Oct 2016 ‘ Detect SMB1 traffic Is there a way to detect SMB1 traffic? Microsoft recommends to stop using it so I’d like to see if it’s being used in our network.’
  • US Law firm
    • ‘Alert if a lawyer uploads huge files to our shared server within a short period of time using up all our space’

Some seem very obvious, simple but on closer examination, most make sense. Also, it is interesting to note that most customers do not request that many, maybe because they are already flooded with false positives and find it almost impossible to actually spot the real actionable alerts.

Machine Learning

I had a chat with a customer last week who purchased a pretty well known ‘machine learning’  based network security products 6 months ago, when he mentioned the product name, I was very curious and asked how it was going. ‘Nothing yet, 6 months of false positives, but you know, it is still learning’. So now not alone have they invested a lot of time and money in purchasing and implementing a product but it is also costing them time wise every day, as it giving them even more false positives to investigate!

Actually, a small number of our customers who requested the alerts included in the list above have recently implemented some expensive ‘Machine learning’ based security products. We started discussing it here internally and it got us wondering about the massive hype by vendors, analysts etc, around machine learning with respect to security. What is really driving it ? The lack of skilled security analysts is definitely one factor, big data another, but another one is surely the current set of overly complex and expensive security products ? And maybe he venture capitalists who have invested huge amounts of money in companies developing this technology, many of whom are struggling with sales ?

Developing Our Own Alerting Engine

We are putting huge focus on the usability of our alert engine, make sure it is as easy as possible to define the rules that generate real actionable alerts, not false positives, the alerts important to the user, the organisation, the business.

Of course, sometimes the simple and best ones are not that easy to implement. For example, as in the case of a lack of a DNS query require context/state and some understanding of the protocol in use in order to generate an alert. As mentioned by one of our engineers, some are also somewhat vague and require more detail. It may also be that some do not require an instant alerts, a simple email sent to the administrator each morning may suffice.

It will take time to get right, some tuning, knowledge of the network etc. Ease of use, readable data, is a must otherwise it will never work. These are basics some security vendors simply do not pay enough attention to but instead spend a lot of time and money on graphics and web interfaces designed by gamers, dark constellations which look fantastic but when you start to look at the detail, looking for actionable intelligence, you start thinking what is this really telling me ?

There are many common and critical threats or ‘bad’ network and user activities that do not require sophisticated artificial intelligence or machine learning.  Most organisations do not have the resources to monitor various dashboards to actually try and detect suspicious activity in real time,  but simply want a real alert with some readable context and data to understand what the alert is actually telling them.

Where to Start

Is it not common sense, start small, work the basics. Use a network traffic analysis for example to monitor internal activity and get the visibility you need to understand what is happening on your network. Modify your ‘active’ systems for example your firewall, to get rid of everything that could widen your attack surface and then add alerts, one by one, to ensure you are immediately notified the next time.  Use forums, blogs, your own network to keep in touch and build and update your own alert set. Add them one by one, you will be amazed with the size of your list after a few months and the lack of false positives.

Did Any Zombie Creep Into Your Network During Halloween?

zombie on network

Network Zombies

Now that Halloween is behind us we can put away the scary decorations and funny costumes. It may also be a good time to check our networks for zombie hosts or users. They can take many forms

  1. Clients infected with Malware which form part of an external botnet
  2. Faulty equipment which may be generating excessive broadcast traffic
  3. Rouge IoT devices eating bandwidth
  4. External clients scanning your network perimeter and exploiting firewall holes
  5. Misuse of network resources by one or more users

Infected Clients

Many networks have lots of security devices at the network edge. From Firewalls to IPS type systems, securing the perimeter has been a priority for many IT managers. The trouble is that while this is a good thing to do, malware can still get in and unless you are monitoring what is going on inside your network you may be at risk. A user may bring in a USB stick laden with Malware for example and walk past your firewall.

I recently read about this network breach where unauthorized software was found on a server and it may have led to data loss. Some time ago I installed a trial version of our LANGuardian product onto a network and we found a client sending over 10,000 SPAM emails per hour. The interesting thing here was that the user of the computer was not complaining and an antivirus scan did not find anything. In the end the IT manager had to get the system reinstalled.

One way to find out what is happening on your internal network is to monitor network traffic moving through your core switch by setting up a SPAN or mirror port. Network traffic is an excellent source of user and application information. Once you have your data source in place a combination of network based intrusion detection and metadata analysis will root out any suspicious activity.

The image below taken from our own LANGuardian system shows an example of what to look out for. Events such as ET MALWARE Win32/InstallCore Initial Install Activity 1 or ET TROJAN W32/WannaCry.Ransomware Killswitch Domain HTTP Request 1 need to be investigated and the associated clients need to be removed from the network.

Network based IDS

Faulty Network Equipment

Technology can be wonderful when it works but when something goes bad it can be a nightmare to figure out what went wrong. A few years back there was massive disruption to air traffic at Dublin airport when a network card went faulty and caused the breakdown of a radar system. Our support team here worked with one of our own customers a while back when a faulty IP phone brought down an entire network segment by sending out large volumes of broadcast traffic.

Make sure you have some sort of internal traffic monitoring in place and watch out for what systems are sending large volumes of broadcast or multicast traffic. In other cases you may need to look at switch interface counters such as collisions or CRC rates. The image below is from our LANGuardian product and show a sample report which is the top clients associated with broadcast traffic. Any devices associated with hundreds of megabytes of broadcast traffic would need to be investigated.

Rogue IoT devices

Almost everything in today’s world is connected. From light bulbs to fridges, many devices now want to share data and metrics. However, this IoT world is not without its challenges. Recently security researches uncovered a botnet called Reaper which may have infected over 1 million networks.

IoT Botnets are Internet connected smart devices which have been infected by the same malware and are controlled by a threat actor from a remote location. They have been behind some of the most damaging cyberattacks against organizations worldwide, including hospitals, national transport links, communication companies and political movements.

You need to be aware of what is connecting to your network. One way to do this is to monitor all traffic going to and from your DHCP and DNS servers. This can reveal a lot about what is connecting to your network and what they are trying to get to. The images below from our LANGuardian product show how metadata captured from DHCP and DNS traffic can used to get an inventory of what is on your network.

If you do have IoT devices on your network, you need to make sure they are fully patched and not using any default passwords.

External Clients Targeting Your Network

As I mentioned previously there are large botnets out there ready to target unsuspecting businesses and organizations. If you re unlucky enough to be targeted you could be on the receiving end of large DDoS attack. Typically NTP or DNS traffic is used to overload your Internet gateways resulting in a loss of connectivity for internal and external clients. Make sure you are monitoring all traffic at your network edge especially the levels of UDP based protocols such as NTP or DNS.

Also watch out for any external clients scanning your network looking for open ports on firewalls. Common scans would be on RDP (TCP 3389), SSH (TCP 22) or SQL (1433). You need to take action if you see any connections on your internal network from clients which are outside the network. Either block the external IP address or shutdown the port they are using on your firewall. Don’t forget to carry out a forensic investigation on any incidents and see if any other client was targeted inside your network.

The image below from our LANGuardian product shows and example of what to watch out for. Here we can see an external IP which is registered in Russia connecting to servers on the local network over TCP port 445.

Rogue Network Users

Sometimes a network user can go bad. Maybe they install an application such as Bittorrent and hog all of the Internet bandwidth or maybe someone accidentally or deliberately deletes data. Can you track down all activity by username? One way to do this is to capture user logon information from Active Directory and use this to match it to IP addresses so you can see who is doing what.

The image below from our LANGuardian product shows a sample user report which lists the top users active on the network based on data downloaded or uploaded. You may want to consider getting alerts if users go above certain levels.

Root Out Zombies on Your Network

Use the deep packet inspection engine of LANGuardian to continuously monitor user and device activity and root out any zombies on your network. Real time and historical reports available. No need to install any agents or client software

  • Built in intrusion detection system
  • GeoIP reports allow you so see what countries are connecting to your network
  • AD integration associates usernames with network activity

All analysis is done passively using network traffic analysis and you will see results within minutes.

QUIC Protocol Detection Now Available in LANGuardian

QUIC Protocol

What is the QUIC Protocol?

QUIC (Quick UDP Internet Connections, pronounced quick) is a transport layer network protocol designed by Jim Roskind at Google. QUIC supports a set of multiplexed connections between two endpoints over User Datagram Protocol (UDP), and was designed to provide security protection equivalent to TLS/SSL, along with reduced connection and transport latency, and bandwidth estimation in each direction to avoid congestion. QUIC aims to be nearly equivalent to an independent TCP connection, but with much reduced latency.

The most common use of QUIC today is for streaming YouTube videos. If you use a Chrome browser then data associated with your YouTube activity uses the QUIC protocol. Some reports suggest that QUIC now accounts for more than 5% of Internet Traffic. Other browsers such as Opera version 16 and above also support the QUIC protocol but don’t have it enabled by default.

How to detect QUIC protocol use on your network

The most reliable way to detect QUIC protocol use on your network is to monitor network traffic at your network edge. Our LANGuardian product can use this data source to look at packet payloads and identify what protocols are in use. The video below shows how to set up a SPAN or mirror port to capture traffic at your network edge.

Once you have your LANGuardian in place you need to click on Reports \ Top Protocols. In my case the QUIC protocol account for 78% of bandwidth use.

Drilling down on this we can then see the Googlevideo domain and the usernames associated with this activity. Googlevideo is the domain Google use for streaming YouTube content.

Drilling down on QUIC traffic

Upgrade your LANGuardian to enable QUIC detection

QUIC detection was added to LANGuardian version 14.3.2. If you are a customer you must upgrade to this or higher version. Click on the gear symbol top right, then settings \ LANGuardian software upgrade. Your LANGuardian must have Internet access to check for and download the latest version.

If you are not a LANGuardian customer then you can download a 30 day trial and see within minutes how much bandwidth the QUIC protocol is using on your network.

How to Detect BitTorrent Traffic on your Network

Monitor Bittorrent Traffic

What is BitTorrent Traffic?

BitTorrent is a communication protocol for peer-to-peer file sharing (“P2P”) which is used to distribute data and electronic files over the Internet. It is most famous as a method for downloading copyrighted material such as movies and music. However, it can be used for software delivery and Microsoft have some P2P capabilities built into Windows 10 for distributing Windows updates.

When it comes to monitoring BitTorrent traffic you need to understand how the protocol works. It is not like a traditional download, where you download everything from a single link or IP address. Instead, you download pieces from other clients (peers) and the management is looked after by trackers or more commonly Distributed Hash Tables. Every download has an associated INFO-HASH value which is unique to it and this is an important piece of data when it comes to identifying BitTorrent traffic.

Capturing BitTorrent Traffic

There are multiple potential data sources if you want to monitor BitTorrent traffic on your network.

  • Monitor network traffic at your network edge using a SPAN, mirror port or TAP
  • Flow records such as NetFlow or IPFIX
  • Firewall logs

The most reliable source is network traffic as “packets don’t lie”. Flow records will not capture metadata such as INFO-HASH values, so you will never know for definite that traffic is associated with BitTorrent activity. Firewall logs may indicate the presence of BitTorrent, but they are not designed as a forensics tool to store long-term records of all traffic and application information.

The video below shows how to set up a SPAN or mirror port to capture traffic at your network edge. With a tool like LANGuardian connected to this, you can identify BitTorrent traffic and capture important metadata such as INFO-HASH, IP addresses, external clients and file names.

Analyzing BitTorrent Traffic

When it comes to analyzing BitTorrent traffic you need to be watching out for these applications:

  • BitTorrent DHT Tracker
  • BitTorrent Peer Traffic

Once you detect these applications on your network, you need to capture certain metadata so you don’t need to store every packet which can be expensive. The image below shows the output of a LANGuardian BitTorrent analysis report. Note how you can see the network user, IP address, INFO-HASH and file name.

Bittorrent Traffic With Usernames

If the download is associated with a private tracker you may not see any filenames. In that case you should look at the destination IP addresses as they can reveal a lot about the applications associated with the Bittorrent traffic. In the image below we can see that there is some Bittorrent activity associated with a client and looking at the destination IP addresses it would appear that the user has the uTorrent application installed.

Private Bittorrent Tracket

Tracking BitTorrent Traffic on Your Network

Download a free trial of LANGuardian today, if you would like to check for any BitTorrent activity on your network. It comes with a fully featured BitTorrent reporting engine together with Active Directory integration, so you can associate network activity with usernames.