Facebook Google Plus Twitter LinkedIn YouTube RSS Menu Search Resource - BlogResource - WebinarResource - ReportResource - Eventicons_066 icons_067icons_068icons_069icons_070

Tenable Blog

Subscribe

Finding Snort Sensors

Over the past few years, there have been several vulnerabilities disclosed about the Snort network intrusion detection sensor. I recently had a Tenable customer inquire for a strategy of "scanning" to find these Snort systems. This blog discusses some basic and more advanced ideas and issues on how to approach this with Nessus and the Passive Vulnerability Scanner.

Network Scanning of Passive Listening Devices

Solutions like Snort sniff packets on a network interface for evidence of network abuse and log this data to SYSLOG, a local file or some sort of log agent.

Typically, there are no daemons or open ports that can be probed or fingerprinted which indicate that Snort is indeed installed. In many cases, best practice for running a network IDS also recommends that the monitoring interface not even have an IP address.

There have been tools and research in the past used to identify devices that are sniffing, but these don't specifically identify Snort. A good example of this is the AntiSniff tool written and released by the L0pht.

Using Credentials to Find Managed Snort Packages

If Snort is included or supported with your OS distribution, Nessus may likely have some client side checks to look for these security issues. At nessus.org, using the plugin search interface, there were eight different UNIX patch audits concerning Snort as shown below:

Snort8plugins

There are a few issues with looking for Snort this way though:

  • Many Snort users obtain distributions directly from snort.org and not the operating system provider
  • Some Snort users hand compile their distributions
  • Relying on the patch from an operating system vendor might take longer than getting it directly from Snort.org.

Scanning for Snort Files

Nessus Direct Feed customers can look for evidence of Snort installations on UNIX systems with the following .audit file:

<check_type: "Unix">
<custom_item>
type: PROCESS_CHECK
  description: "Check snort process status" 
  name: "snort"
  status: OFF
</custom_item>
</check_type>

This audit simply checks if the 'snort' process is running and reports a failure if it is detected. This scan requires SSH credentials to perform the audit.

Passive Network Monitoring

The Passive Vulnerability Scanner can detect systems that send SYSLOG messages which contain "snort" logs. If your organization uses SYSLOG to send logs from your Snort sensors to a central location, PVS rule #3986 will identify those systems. The rule will also match a secondary log server which is forwarding log which contain Snort events as well.

In order to see these logs, the PVS would need to observe the SYSLOG traffic. If your PVS was on the perimeter of your network and your Snort sensors were further inside and logging to an internal host, it would not be able to observe the traffic.

For More Information

If running Snort alongside Tenable products is interesting to you, please consider these other blog entries:





Related Articles

Cybersecurity News You Can Use

Enter your email and never miss timely alerts and security guidance from the experts at Tenable.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy.

Your Tenable Vulnerability Management trial also includes Tenable Lumin and Tenable Web App Scanning.

Tenable Vulnerability Management

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

100 assets

Choose Your Subscription Option:

Buy Now

Try Tenable Web App Scanning

Enjoy full access to our latest web application scanning offering designed for modern applications as part of the Tenable One Exposure Management platform. Safely scan your entire online portfolio for vulnerabilities with a high degree of accuracy without heavy manual effort or disruption to critical web applications. Sign up now.

Your Tenable Web App Scanning trial also includes Tenable Vulnerability Management and Tenable Lumin.

Buy Tenable Web App Scanning

Enjoy full access to a modern, cloud-based vulnerability management platform that enables you to see and track all of your assets with unmatched accuracy. Purchase your annual subscription today.

5 FQDNs

$3,578

Buy Now

Try Tenable Lumin

Visualize and explore your exposure management, track risk reduction over time and benchmark against your peers with Tenable Lumin.

Your Tenable Lumin trial also includes Tenable Vulnerability Management and Tenable Web App Scanning.

Buy Tenable Lumin

Contact a Sales Representative to see how Tenable Lumin can help you gain insight across your entire organization and manage cyber risk.

Try Tenable Nessus Professional Free

FREE FOR 7 DAYS

Tenable Nessus is the most comprehensive vulnerability scanner on the market today.

NEW - Tenable Nessus Expert
Now Available

Nessus Expert adds even more features, including external attack surface scanning, and the ability to add domains and scan cloud infrastructure. Click here to Try Nessus Expert.

Fill out the form below to continue with a Nessus Pro Trial.

Buy Tenable Nessus Professional

Tenable Nessus is the most comprehensive vulnerability scanner on the market today. Tenable Nessus Professional will help automate the vulnerability scanning process, save time in your compliance cycles and allow you to engage your IT team.

Buy a multi-year license and save. Add Advanced Support for access to phone, community and chat support 24 hours a day, 365 days a year.

Select Your License

Buy a multi-year license and save.

Add Support and Training

Try Tenable Nessus Expert Free

FREE FOR 7 DAYS

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Already have Tenable Nessus Professional?
Upgrade to Nessus Expert free for 7 days.

Buy Tenable Nessus Expert

Built for the modern attack surface, Nessus Expert enables you to see more and protect your organization from vulnerabilities from IT to the cloud.

Select Your License

Buy a multi-year license and save more.

Add Support and Training