Conficker's Next Move

I recently attended a presentation about the current state of the Conficker worm, delivered by Felix Leder and Tillman Werner, two German security researchers from the <a href="" target="new">University of Bonn</a>.

Wolfgang Kandek, Contributor

November 11, 2009

3 Min Read

I recently attended a presentation about the current state of the Conficker worm, delivered by Felix Leder and Tillman Werner, two German security researchers from the University of Bonn.It was a real privilege to meet them and exchange some thoughts since we at Qualys had been using their research work extensively since the end of March 2009, when the whole Conficker worm detection effort started.

Here is what is new: Conficker is still spreading. The latest results show we are dealing with more than 6 million infected IPs, up from 4 million in June. But in mid-July something happened that slowed the overall growth:


In July, Felix and Tillman used a quirk/feature of Conficker.A to neutralize the variant and stop it from spreading. On startup, Conficker.A consults a GeoIP database through the Internet, and if the IP address of the machine is located in the Ukraine, then it simply shuts down. The original GeoIP service being accessed had since decommissioned the URL used by Conficker (too much traffic and all nonproductive) and was willing to forward all requests to the University of Bonn, where Tillman and Felix started to serve a one-line version of the GeoIP database, putting all IPs squarely into the Ukraine. This slowed the spread of Conficker significantly as the difference in slope indicates. Very simple, smart, and effective.

The chart also shows this A variant, if left undeterred, will contribute significantly to the overall growth of Conficker. Given that Conficker.A uses exclusively the flaw patched in MS08-067 for its propagation method, a large quantity of vulnerable Windows machines still must be out on the Internet ready for infection. The threat in this situation is not that the Conficker worm will eventually get to these PCs, but that any enterprising bot author is able to write a new worm abusing the same flaw, with a high likelihood of building a major botnet.

Patch progress for MS08-067 is apparently slowing down, and the remaining machines will not get fixed without a major awareness campaign. As an alternative, should we work with the ISPs to help protect against this threat? One the major broadband providers in the U.S., Comcast, announced recently it will start monitoring its consumer network for botnets. So Comcast is apparently already thinking along those lines, as well.

-- As the CTO for Qualys, Wolfgang Kandek is responsible for product direction and all operational aspects of the QualysGuard platform and its infrastructure. Wolfgang has more than 20 years of experience in developing and managing information systems. His focus has been on Unix-based server architectures and application delivery through the Internet. Wolfgang provides the latest commentary on his blog: and also publishes his Patch Tuesday commentary to the QualysGuard channel: He is a frequent source in business and trade media and speaks at industry conferences around the world, most recently at RSA 2009.

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