Thursday, December 27, 2012

Disclosure of another 0day malware - Update and Additional Information

At first I will provide an overview of the current AV detection rates, almost 2 weeks after publishing the MD5 hashes of this malware. I will also release the samples, so you can analyze it by yourself, if you are interested. Thereafter I show the statuses of the (known) Servers involved in this threat and give the directory listings. Next, I try to shed some light into the origin of this malware. At last I will provide a brief analysis of an older version of this malicious software (thanks Artem for providing the sample!). This older version is mentioned in the following reports:


Sunday, December 16, 2012

Disclosure of another 0day malware - Analysis of the final Payload (Part 3)

In the last Part of this series I partly analyzed the final Payload. I haven't finished the analysis of the malware due to lack of time (and interest), but I will provide as much as information I have discovered. It looks like this malware is a classic spying tool (information gathering), but it would be interesting to know who is the attacker and who are the victims. Unfortunately I don't have a chance to reveal the identity of both and speculation is also not possible since the lack of any hints.
The final Payload also wasn't uploaded to Virustotal, so the detection rates supposedly are very low.

Final Payload
Sample: netui.dll
Size: 37.376 Bytes
Timestamp: 09.06.2012 12:27:19
MD5: AA3E6AF90C144112A1AD0C19BDF873FF

We start by examing the Export functions of this .dll.


Saturday, December 15, 2012

Disclosure of another 0day malware - Analysis of 2nd Dropper and 3rd Dropper (Part 2)

In the second Part of this series we analyze the downloaded file (2nd Dropper) and the dropped file (3rd Dropper). At time of this analysis the files weren't uploaded on Virustotal, so I guess the detection rates are very low, if at all.

2nd Dropper
Sample: msmvs.exe
Size: 80.388 Bytes
Timestamp: 25.07.2012 06:51:13
MD5: 66F368CAB3D5E64475A91F636C87AF15

3rd Dropper
Sample: conhost.dll
Size: 62.976 Bytes
Timestamp: 25.09.2012 08:23:13
MD5: F1704AAF08CD66A2AC6CF8810C9E07C2


Disclosure of another 0day malware - Initial Dropper and Downloader (Part 1)

In this series I have analyzed an interesting malware that combines various techniques I haven't seen before. Part 1 of this series deals with the initial Dropper and the Downloader which both come in the form of a Dynamic Link Library (.dll). The initial Dropper drops and executes the Downloader (netids.dll). Part 2 deals with the downloaded file, which is just another Dropper (msmvs.exe). This Dropper drops a .dll (conhost.dll) which in turn drops the final Payload (also .dll). Part 3 deals with the final Payload (netui.dll). Note: Due to lack of time (and interest), I haven't completely analyzed the final Payload.

Figure 1: Overview of the malware components

I don't know how the initial Dropper will be delievered to the victim, because a .dll in some way has to be loaded (Export function call, rundll32.exe, ...). Some reports on ThreatExpert indicate that the Dropper is executed with the help of an exploit (Adobe Acrobat, Microsoft Word): (Note: Sometimes Threatexpert doesn't work)

Maybe the malware is used for a targeted attack in a spearfishing campaign. I also have found a Symantec report from 2011 mentioning some behaviours of the .dll, but it seems the one I have analyzed is a newer version of the malware family:

What makes this malware interesting:
- It makes use of an unknown (AV) Anti-Emulation technique
- Contains Anti-Debugging and Anti-Reversing techniques
- Suspicious strings and the payloads are encrypted
- Suspicious Windows API functions are dynamically resolved
- Downloader and final Payload are (also) implemented as a Windows Service
- Uses multiple encryption techniques (e.g. RC5/6)
- Uses the "Common Gateway Interface" (cgi) for data transfers
- Supports Unicode encoding