Thursday, August 04, 2005

Analysis of a Win2K rootkit

I ran across this site recently (can't remember where I originally got the link) and finally got around to actually reading through it.

The first thing that jumps out at me is that the content is incorrectly titled. When talking about rootkits, particularly on Windows systems, the term most generally refers to tools that are used to hide the attacker's presence from not only the Administrator, but the operating system and native tools, as well. However, I suppose that since the attacker "had root", used two self-extracting archives (kits) to move his tools over, and "hide" from casual viewing by (a) using the attrib command, and (b) deleting some files, then technically, it is a "root kit".

Like I've said before, I really like to see things like this posted...seriously. I've heard from others that not only are such things interesting to read, but they provide a great learning opportunity, and I wholeheartedly agree.

I do have a couple of suggestions for improvement, and a question. First, the question...the author makes reference to the HKU\{SID}\Software\Microsoft\Internet Explorer\Explorer Bars\{GUID}\FilesNamedMRU key, and seems to indicate that this location can be used as an autostart location (ie, "...thus executing all of the files listed if any one of them is started.").

Does anyone have any insight on this? I'm going to try this out and see what happens, but I'd love to know how close he is on this.

Okay...suggestions...constructive stuff. I like the screen captures, but there's a lot going on in the article that would really benefit from a screen capture or two. For example, ...used an MSBlaster style exploit to open port 4444 with root privileges... Okay...but can we see that? For example, how about showing the output of fport/openports side-by-side with the output of handle.exe, showing the user context of the process? That would be cool.

Throughout the article, the author speculates as to the intentions of the attacker. I don't necessarily disagree with his assessment of the skill level of the attacker (though I'd like to see more detailed information), but I think that sometimes we can misguide ourselves when we try to guess someone's intentions.

Finally, there are some confusing statements in the article. For example,
  1. The svc.bat file sets the user name of the IRC bot in win.dll (which is actually just a plain text file)...
  2. ...but instead sets the machine up as a warez server via IRC. The bot installed connects to and joins the channel #XiSO...
  3. Edit the C:\WINNT\system32\Setup\svchost\ file to find the process id (PID) of the IRC daemon
  4. This stops the IRC daemon from running
  5. ...suggest the intended use for this kit is not just to run an IRC bot...

So, is it a 'bot or a daemon? Client or server? It sounds like it's a 'bot/client, based on the explanation, but the use of the term 'daemon' suggests a server or service. This is an important distinction.

The author says, "This results in 3 processes called lsass.exe, though only one is legitimate." This demonstrates a "hiding" technique that still works. Basically, the attacker started several processes named "lsass.exe", but because the executable images weren't in the system32 directory, there were no issues with WFP. Even though you won't see the full path to the executable images in the Task Manager, just having more than one copy of lsass.exe running should be a tip to even the most casual observer. Now, using 'svchost.exe' is another matter entirely...

Overall, a great job. Shout-outs/greetz to the author.

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