Tag Archives: Acunetix

Potential RCE in Nessus 7 and attacks on Vulnerability Scanners

A few days ago I saw an interesting youtube video (UPD. 14.05.18 Not available anymore) in my Facebook feed. It is demonstrating the exploitation of the RCE vulnerability in Tenable Nessus Professional 7.0.3. Currently we have very few information about this vulnerability: only youtube video, which is mentioned only on ExploitWareLabs facebook page.

Nessus 7.0.3 RCE

While there is no exploit in public access, it’s hard to say how it actually works. It’s also not clear what versions of Nessus are affected. 7.0.3 is the latest version currently. Because of API disabling in Nessus 7 many users are still on 6.11.3. It is not clear whether they are affected or not.

This even can be a fake video. Therefore, I specifically write “potential RCE”. I will update this post when more data is available.

UPD. 14.05.18 In the comments to my Facebook post anonymous account Destring Portal posted a comment with the second video of Nessus RCE exploitation and it seems, that it was made by the same author. In this video, the author runs a remote shell on the Nessus host and executes various commands. I will add review of this second video bellow.

Nessus RCE second video

UPD. 10.05.18 Renaud Deraison, Co-Founder and CTO of Tenable, commented on my post at Linkedin:

Our research team studied the video and we have several reasons to doubt its authenticity. We’ve conducted a thorough audit over the last 48 hours based the few details that are in the video and didn’t find anything. We reached out the researcher and instead of replying he removed the video*. We’ll communicate if indeed there is a risk.

In general, you are right though – the security of scanners is of paramount importance. This actually is a topic I’ve been extremely worried about ever since the early days of Nessus. We have a number of security mechanisms in place (interpreted language for the detection scripts, ciphered temporary files, very limited runtime environment) which really aim to limit the risk of being exploited but also to mitigate the risk should the scanner be compromised. I actually did a few talks in the past about scanning “rogue hosts” and we continue to treat all input as hostile.

Again, we’re continuing to investigate the matter and will let you know if we find anything.

* currently video is still available on the same address; it could be probably blocked for some time. (UPD. 14.05.18 Not available anymore)

In any case, it’s a good reason to talk about vulnerabilities of such kind, how they appear and how to protect Vulnerability Scanners from attackers.

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A few words about Gartner’s “Magic Quadrant for Application Security Testing” 2018

February and March are the hot months for marketing reports. I already wrote about IDC and Forrester reports about Vulnerability Management-related markets. And this Monday, March 19, Gartner released new “Magic Quadrant for Application Security Testing”. You can buy it on the official website for $ 1,995.00 USD or download it for free from the vendor’s sites. For example, Synopsys or Positive Technologies. Thank you, dear vendors, for this opportunity!

I’m not an expert in Application Security. I am more in Device Vulnerability Assessment (IDC term) or Vulnerability Management. However, these field are related. And well-known Vulnerability Management vendors often have products or functionality for Web Application scanning and Source Code analysis as well. Just see Qualys, Rapid7 and Positive Technologies at the picture!

Gartner AST MQ 2018

I have already mentioned in previous posts that grouping products in marketing niches is rather mysterious process for me. For example, Gartner AST niche is for SAST, DAST and IAST products:

  • SAST is for source code or binary analysis
  • DAST is basically a black box scanning of deployed applications. it can be also called WAS (Web Application Scanning)
  • IAST is a kind of analysis that requires agent in the test runtime environment. Imho, this thing is still a pretty exotic.

As you can see, these are very different areas. But, the market is the same – AST.

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Vulnerability Management for Network Perimeter

Network Perimeter is like a door to your organization. It is accessible to everyone and vulnerability exploitation does not require any human interactions, unlike, for example, phishing attacks. Potential attacker can automate most of his actions searching for an easy target. It’s important not to be such of target. 😉

Vulnerability Management for Network Perimeter

What does it mean to control the network perimeter? Well, practically this process consist of two main parts:

  • Assessing network hosts that are facing Internet using some Network Scanner (Nessus, OpenVAS, Qualys, MaxPatrol. F-Secure Radar, etc.)
  • Assessing application servers, e.g. Web Servers, on these hosts using some special tools, e.g. Web Application Scanners (Acunetix, Burp Suite, Qualys WAS, Tenable.io WAS, High-Tech Bridge ImmuniWeb, etc.)

Active scanning is a good method of perimeter assessment. Dynamics of the assets is relatively low, comparing with the Office Network. Perimeter hosts usually stays active all the time, including the time when you are going to scan scanning them. 😉

Most of the dangerous vulnerabilities can be detected without authorization: problems with encryption (OpenSSL Heartbleed, Poodle, etc.). RCE and DoS of web servers and frameworks (Apache Struts and Equifax case)

The best results can be achieved with scanners deployed outside of your network. Thus, you will see your Network Perimeter the same way a potential attacker sees it. But certainly, you will be in a better position:

  • You can ask your IT administrators to add your network and WAS scanners in white list, so they will not be banned.
  • You can check and correlate scan results of remote scanner with (authenticated?) scan results produced by the scanner deployed in your organization’s network and thus filtering false positives.

What about the targets for scanning? How should you get them?

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OpenVAS plugins in Vulners.com

Great news! Vulners.com vulnerability search engine now supports OpenVAS detection plugins.

OpenVAS plugins Vulners

Why OpenVAS is important?

OpenVAS is the most advanced open source vulnerability scanner and is the base for many Vulnerability Management products.

Key vendors that produce OpenVAS-based products are Greenbone and Acunetix. There are some local vendors, such as Scaner VS by Russian company NPO Echelon.

“Vanilla” OpenVAS is also widely used when there is no budget for a commercial solution or it’s necessary to solve some specific problems, including developing own plugins for vulnerability detection. OpenVAS is integrated with wide range of information security systems, for example it is a default VM solution for AlienVault SIEM.

OpenVAS is well suited for education purposes as it is well documented and uses only open source code. For OpenVAS it’s always clear how the it works.

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