Anatomy Of A Client-Side Attack Using Metasploit

A new report from the SANS Institute sheds light on some important attack trends that security professionals need to take action on immediately.
A new report from the SANS Institute sheds light on some important attack trends that security professionals need to take action on immediately.The glaring issues are Web application and desktop application vulnerabilities that are being used for combined attacks -- making for a successful one-two punch. The graphs and statistics are useful, but I think the graphical example of a HTTP client-site exploit really drives home the reality and ease in which these attacks can be carried out.

I highly recommend you take a look at the example in the report if you haven't already. It's titled "Tutorial: Real Life HTTP Client-side Exploitation Example." As I was reading through it, I couldn't help but think of the recent malvertisement incident I wrote about yesterday.

In Step 0 of the example, the attacker places content on a trusted site, which is exactly what happened with the incident. The difference is the example exploits a client-side vulnerability instead of trying to lure the user into running a fake AV tool and infecting hhimself.

While the similarity in the first part of the attack is interesting, this type of attack is not rocket science. Every single step can be carried out using free and/or open source software that is available for anyone to use. I was originally planning to give examples of the tools to use for each step, but the fact is that every single step can be carried out using the Metasploit Framework.

In Step 0, an attacker (or penetration tester) creates a weaponized PDF file using Metasploit (possibly using the Adobe JBIG2Decode Memory Corruption Exploit) and places it on a social networking site. In Step 1, the victim (or client of the pen-tester) opens the PDF that exploits one of the numerous recent vulnerabilities in Adobe Acrobat. The exploitation results in an meterpreter backdoor for the attacker via HTTPS as discussed in Step 2.

Steps 3 and 4 is where the example gets interesting because pass-the-hash attacks don't make it into the mainstream media like Web and client-side vulnerabilities do. In Step 3, the attacker dumps the local account password hashes and, instead of cracking them with rainbow-tables, "passes" the Administrator's hash to gain access to other systems in Step 4 and eventually, a Microsoft Active Directory Domain Controller in Step 5. Again, all of this can be done in Metasploit, which you can see in this excellent example video demonstrating the Pass-the-Hash attack.

Steps 6 and 7 are where the attacker goes for the crown jewels and starts pilfering data out of the victim's network over HTTPS, thwarting the victim's network-based DLP solution because he can't view the encrypted HTTPS session. Awesome, isn't it?

The report is worth the read and is something you can use to slap your executives around in an effort to get the funding you need to start cleaning up those Web apps and patching those third-party apps. But one of the real gems is this example of a real attack in simple terms and illustrative graphics should really help you get your point across. Oh, and just wait until you tell them you can carry the entire attack out using a freely available tool.

John H. Sawyer is a senior security engineer on the IT Security Team at the University of Florida. The views and opinions expressed in this blog are his own and do not represent the views and opinions of the UF IT Security Team or the University of Florida. When John's not fighting flaming, malware-infested machines or performing autopsies on blitzed boxes, he can usually be found hanging with his family, bouncing a baby on one knee and balancing a laptop on the other. Special to Dark Reading.

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