In my last two diaries (http://isc.sans.org/diary.html?storyid=6001 and http://isc.sans.org/diary.html?storyid=6010) I described two very common attacks on web servers that I have seen in the wild recently. During the forensic analysis, I acquired two attack tools that were used in almost all cases, so here is a short description of them.
However, in cases where they couldn’t do this (for one reason or the other), they used a very simple file injection named JS.exe, which you can see disassembled below:
The other attack tool I recovered is a log cleaner for Windows. It’s another simple tool which allows attackers to easily delete all IIS, FTP and EventLog logs. The help window is shown below:
While the both files are very simple, finding them solved another puzzle that troubled many web administrators lately as attacks such as those I describe are becoming increasingly common.
I’d like to use this opportunity to warn people about the “unpatched” Windows vulnerability described in http://isc.sans.org/diary.html?storyid=6010 again, since I’ve seen it used in the wild again. While Microsoft listed some workarounds, for most users using IIS 6 they will not be acceptable as they require one to disable the Distributed Transaction Coordinator service. The workaround for IIS 7 is better, but some (many?) shops can’t easily migrate to it so they are kind of left in the open.
If you have more experience or comments about these workarounds please do contact us.
I will be teaching next: Web App Penetration Testing and Ethical Hacking - SANS Amsterdam January 2021