Monday, July 19, 2010

Messenger Abuser Malware Tactics

A common trend I see in both research and job duties is the use of instant messaging services to propagate malware.
"OMG, Russ," you say, "groundbreaking!" I know, I know.
This is all about tactics and trends.
Pushing malware through URLs sent over instant messaging should surprise no one who spends anytime in the infosec space, but once in awhile I spot persistent methods that are, if nothing else, relentless in their pursuit of victims.
You know the vector. A URL pops up in the IM client, victim clicks, off to the races.

With the vast popularity of social networking services, one obvious trait includes Facebook-oriented nomenclature where a URL and attacker domain might include the likes of hxxp://
"Look, Ma! It's from my Facebook friend! It's gotta be safe!" Uh-huh.
What's been interesting lately has been the number of executables that are named as image files; most often JPG as seen above.
Said sample above is Backdoor.Win32.Gootkit.

Another one following this pattern lately was found at hxxp://
A recent sweep for the string as part of this analysis found it referenced in the following:
hxxp:// (suspended)
hxxp:// (suspended)
Inevitably, they're served from a hacked server too, as seen on; when explored at it's root offers Figure 1.

Figure 1

The binary disguised (thinly) as FOTO3436812.JPG is an unspectacular IRC bot with a tenacious master, given the numerous URL variants pointing to the same sample.
A quick run through ye olde sandbox produces a PCAP and behavioral analysis that indicates classic IRC behavior; again, very typical stuff known in some circles as the LolBot. But the bad guy (or so it seems) was nice enough to leave his "Facebook badge" on the server that the initially executed package calls home to for additional downloads. One directory jump up from where said additional download resides and you have Figure 2 (anonymized to protect the miscreant).

Figure 2

Nice, nothing like putting a face with your malware. ;-)

How about the endless VBTrojan malware served up with a bit of Brazilian (calls home to spice via the file name (see the trend?):
The strings references include "desconhecido" ("unknown" or "strange" in Portuguese) and C:\Arquivos de programas. ;-) Beware the arquivos!

My favorite of late has been this one pushed behind a TinyURL.
This one was pretty good and there's very little detection for the binary yet.
The shortened version:
hxxp:// (I love the DSC nomenclature like it just came off a phone or digital camera).
Redirect is to hxxp://, but the catch here is that index.html is actually the binary.
I have to say, I hadn't seen that one used before in this context. The trickery is improving.
But alas, it's still just an IRC bot:
NICK new[USA|XP]8092826
USER s "" "lol" :s

Remember I mentioned the LolBot above with regard to a different sample?
Give it a few days. Once the detection is up to speed for this variant I'm reasonably certain we'll see it classified as Lol/Buzus/Panadol.
I'll take bets: the hash for index.html is 2B4B55CE4A991DBD9600246C7F9E080D.
We'll see if my neanderthal-like ability to spot trends holds water. ;-)

Like I said, what's old is new again. But maybe, just maybe, you learned something useful reading this far.

Sorry it's been a few weeks...busy, busy.
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