SANS ISC: Traffic Patterns For CryptoWall 3.0 - Internet Security | DShield

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SANS ISC InfoSec Forums

This is a guest diary submitted by Brad Duncan.

Various sources have reported version 3 of CryptoWall has appeared [1] [2] [3].  This malware is currently seen from exploit kits and phishing emails.  CryptoWall is one of many ransomware trojans that encrypt the personal files on your computer and demand a bitcoin payment before you can unlock them.

I got a sample on Wednesday, January 14th 2015 while infecting a virtual machine (VM) from a malicious server hosting the Magnitude exploit kit.

If you're registered with Malwr.com, you can get a copy of this CryptoWall 3.0 sample at:

https://malwr.com/analysis/MDA0MjIzOGFiMzVkNGEzZjg3NzdlNDAxMDljMDQyYWQ/

Let's look at the traffic from my infected VM:

In this example, the infected VM checked ip-addr.es to determine its public IP address.  Then the VM communicated with a server at 194.58.109.158 over a non-standard HTTP port.  In this case it was port 2525, but I saw different ports in other hosts I've infected with this sample.

Finally, the user viewed a web page for the decrypt instructions at 5.199.166.220.

When monitoring the infection traffic with Security Onion [5], we see an EmergingThreats alert for CryptoWall check-in [4].

The decryption instructions specify the following bitcoin account for a ransom payment:  1GJRTp9YRKFEvzZCTSaRAzrHskFjEwsZy

Here's what the user would see on their desktop screen:

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Brad Duncan is a Security Researcher at Rackspace, and he runs a blog on malware traffic analysis at http://www.malware-traffic-analysis.net

References:

[1] http://malware.dontneedcoffee.com/2015/01/guess-whos-back-again-cryptowall-30.html
[2] http://www.bleepingcomputer.com/forums/t/563169/after-a-brief-hiatus-malware-developers-release-cryptowall-3/
[3] https://forums.malwarebytes.org/index.php?/topic/163485-cryptowall-30/
[4] http://doc.emergingthreats.net/2018452
[5] http://blog.securityonion.net/p/securityonion.html