The last spreading malware version of Waledac, a notorious spamming botnet that has been taken down in a collaborative effort lead by Microsoft earlier this year, contained some neat anti-debugging tricks in order to make reverse-engineering more difficult. Felix Leder and I have been presenting about the approach at SIGINT 2010 in Cologne yesterday, and as the method seems to be not publicly known yet, I will quickly describe it here as well.
While it seems to be impossible to say whether waledac is the successor of storm or not, what we can do is take a look at the traffic encryption. They guys over at Shadowserver have already blogged some details about this. We at the Giraffe Chapter investigated waledac’s communication protocol further. Here are our results.
Waledac uses regular HTTP request to transmit command requests and to retrieve responses. It uses HTTP fast-flux proxies to hide the true origin of the command&control (C&C) server.
Waledac is wishing merry christmas
There is a new bot in town. It’s called Waledac. The way it is spreading reminds a lot of people of the good old storm botnet: An email is sent containing a “christmas card” in form of the executable “postcard.exe”.
A preliminary view on the binary has been given by the Shadowserver guys (Steve Adair).
I had the chance to have a first look at the binary (MD5 ccddda141a19d693ad9cb206f2ae0de9) and want to note down some of my few findings to let the hunt begin.