Tuesday, December 8, 2009

Poking at the Justexploit kit part 2

Again, some of this analysis has probably already been posted somewhere but in the interests of continuing my process, I will pick up where I left off with yesterdays blog post. Yesterday I went over basically what the Justexploit's MDAC exploit attempted to do, and followed the malware trail for a while.

The second batch of bugs exploited by Justexploit are common Adobe Acrobat Reader issues, all patched. These have been documented to a large degree and are apparently well understood so I won't go into the mechanics. The bugs, which have been hammered by other exploit kits are:

Adobe Collab overflow - CVE-2007-5659
Adobe util.printf overflow - CVE-2008-2992
Adobe getIcon - CVE-2009-0927

Numerous PoC's and weaponized exploits exist for these issues.

The PDF exploitation associated with the sdfnucleartqg dot info site is hosted at /pdf.php and was already submitted by an unknown party to the excellent wepawet sandbox on 12-4-09:


A portion of this blog entry expounds a bit on the wepawet analysis, but is not as pretty. If you want the full details, shellcode bytes and all of the de-obfuscated javascript (heap spray, etc) then please see the wepawet link above. Kudus to the developers of wepawet for it's time-saving properties.

Wepawet does a good job extracting the shellcode from the PDF, as we see in the "Shellcode and Malware" section. The actual payload starts off with a 0x90 based NOP sled, followed by shellcode that points to the downloading and executing of yet another URL from the same site-


The URL is obvious here and points towards the same windows binary pushed by the MDAC exploit. This binary was detected by VirusTotal on 12/2/09 by 10 out of 41 anti-malware engines (24.39%). See the VirusTotal report for full details, however the relevant results are pasted here:


a-squared 2009.12.02 Trojan.Win32.Oficla!IK
CAT-QuickHeal 10.00 2009.12.02 (Suspicious) - DNAScan
Ikarus T3. 2009.12.02 Trojan.Win32.Oficla
Kaspersky 2009.12.02 Trojan.Win32.Sasfis.wox
McAfee+Artemis 5819 2009.12.01 Artemis!8D0F4EC4C458
Microsoft 1.5302 2009.12.01 Trojan:Win32/Oficla.E
Prevx 3.0 2009.12.02 Medium Risk Malware
Rising 2009.12.02 Trojan.Win32.Generic.51F273B2
Sophos 4.48.0 2009.12.02 Sus/UnkPack-C
Sunbelt 3.2.1858.2 2009.12.02 Trojan.Win32.Sasfis.a (v)

See the previous blog entry for a basic analysis of the payload. See the Anubis analysis of this binary for further details:


I have found that Anubis doesn't always give me the level of detail that I need. I personally prefer ThreatExpert's sandbox analysis. Anubis does enumerate network activity, which shows the same target binary that was included with the MDAC exploit.

3.c) svchost.exe - Network Activity
DNS Queries:
Name Query Type Query Result Successful Protocol
h0stels.cn DNS_TYPE_A 1

HTTP Conversations:
From ANUBIS:1038 to - [h0stels.cn]
Request: GET /SHasg2/bb.php?id=590043150&v=200&tm=8&b=justspl
Response: 200 "OK"

It is fair to assume that the Java exploit has the same end result. The exploit code is found in the following JAR (as previously documented elsewhere) - http://sdfnucleartqg dot info/files/sdfg.jar

98d499308df04932ed1b58a78417d6fb sdfg.jar

unzip sdfg.jar
Archive: sdfg.jar
creating: META-INF/
inflating: myf/y/AppletX.class
inflating: myf/y/LoaderX.class
inflating: myf/y/PayloadX.class

Avira catches the Jar as JAVA/OpenStream.AD Java Virus

Since java is trivial to reverse, it's easy to see what's going on. If this hasn't already been done ( I think it has ) I'll do it in part 3. Guessing it's based off of public exploit code for the Java bug released a while back. Why should the malware authors expend energy when they can just leech from security researchers? One of the downsides of people publishing exploits (I digress, this is a distinct topic)

The opening page where the initial Javascript starts the process of infection is dynamically generated with different encoding every time with a new id as such:

ID's generated in this sampling:


Since Wepawet had no problem decoding, I didn't bother running the code through Malzilla or other local decoding tool.

In other news, a URL from the malware chain yesterday has changed it's payload. The page contains what appears to be command & control information for the infection.

http: //h0stels . cn/SHasg2/bb.php?id=555611691&v=200&tm=3&b=3857054178&tid=9&r=1

The new contents of the .cn page points to a new binary:

http: //poezd-v-ad . eu/free1/mqh5.exe

VirusTotal gives what looks mostly like generic detections

9d99e88dfefc6528f4ba912d9d9b1f19 mqh5.exe

AntiVir 2009.12.08 TR/Dropper.Gen
DrWeb 2009.12.08 BackDoor.Tdss.based.3
McAfee+Artemis 5825 2009.12.07 Artemis!9D99E88DFEFC
McAfee-GW-Edition 6.8.5 2009.12.08 Trojan.Dropper.Gen
Panda 2009.12.08 Suspicious file
Sophos 4.48.0 2009.12.08 Mal/TDSSPack-U
TrendMicro 2009.12.08 BKDR_TDSS.SMA

Sure looks like the TDSS rootkit, based on signature scans.

ThreatExpert isn't able to get much from this binary:


# Submitted sample:

* File MD5: 0x9D99E88DFEFC6528F4BA912D9D9B1F19
* File SHA-1: 0x1BEFD04012D725FA38C5F58E50DDDFD29C7A8CAD
* Filesize: 62,464 bytes
* Alias: Mal/TDSSPack-U [Sophos]

I recall TDSS being analyzed previously, however I would like to see what this particular variant is doing. This will be covered in part three, if it's actions are unique.


  1. Hi, I stumbled across this site while trying to figure out something weird on my wife's macbook console. It had a message about creating applet myf.y.appletX and pingcrews.in which sounded kind of weird. After some digging and WhoIs, I traced it back to jobmasterx.yahoo.com which traced back to the Justexploit kit.

    I did find that it had opened a socket and downloaded the sdfg.jar file you discussed earlier as well as a .hst file and and idx file. However, beyond that, I cannot determine if anything has actually happened that would compromise her computer in a serious way. I have run updated versions ClamXav, MacScan, Kaspersky, RootKit Hunter, and none of them have identified that anything is wrong. I run Firefox (it was the previous release (3.5.7?) (Java was enabled) and it is set to clear my history/cache/cookies/etc whenever I close the app.

    This is the threatexpert profile of the zip:

    I guess what I'm trying to figure out is if this exploit is OS Agnostic, or if the Java exploit was effective, but it wasn't able to do much beyond that. Can you provide me with guidance on this?