Conficker contains a piece of code that has been object of speculation: It does not infect boxes located in the Ukraine. Before sending an exploit, it performs a lookup against Maxmind's GeoIP database, which is freely available, and skips the host if the returned country code is UA. While the B variant comes with a copy of the database embedded, the A variant downloads the file from Maxmind's server. A couple of days ago Felix had the idea to deliver a specially crafted database that maps every IP address to the Ukrain.
Many people have asked us, how Conficker looks like. That's a tough question for something that's hidden and tries to be as stealthy as possible. The last time somebody asked me: "Can you show me Conficker?", I decided to visualize Conficker. Here is a little video that shows the evil core of Conficker.C.
Today we released version 2 of our Simple Conficker Scanner (SCSv2). It contains a new scanning method which allows for detection of machines infected with the recent Conficker version (D or E, depending on the naming scheme - the tool calls it D). Although the patch to the vulnerable function NetpwPathCanonicalize() was updated in the new variant, the RPC response codes for specially crafted requests are still different for infected machines.
Joe Stewart from the Conficker Working Group has created an eye chart that allows for online identification of Conficker B and C infections. The idea of trying to load content from sites that are blocked by Conficker is really smart.
As you know, bad things are going to happen on April 1st: people will be sending out emails to their friends, telling silly jokes and putting MTAs under a higher load. Besides that (but not quite that bad), Conficker will activate its domain name generation routine to contact command-and-control servers. We have been researching this piece of malware recently, with a focus on how to detect Conficker-infected machines. Felix and I had a discussion with Dan Kaminsky about the possibilities to actively detect Conficker and wrote a scanner for this task.