Virut Botnet Crippled in Multinational Takedown Effort

Security researchers in several countries worked together to cripple a botnet was estimated to control 300,000-zombie computers.

The Virut botnet has taken a serious hit as security researchers joined forces to go after the botnet's infrastructure.

The takedown effort involved researchers from Poland's Computer Emergency Response Team (CERT), the Spamhaus Project and Russian CERT-GIB aimed at disrupting the operations of Virut, a massive botnet estimated to control 300,000 infected machines. Threat intelligence was also provided by VirusTotal.

In December, Spamhaus worked to have all the Virut domain names registered through various Polish registrars within the .pl ccTLD suspended. However, the gang behind the botnet was able to quickly get the malicious domain names moved to a new registrar called, thwarting takedown efforts, Spamhaus' Thomas Morrison explained in a recent blog post.

The botnet's operations, however, were dealt a serious blow when Poland-based NASK (Research and Academic Network) began to move on the botnet's infrastructure. The NASK operates the Polish Computer Emergency Response Team and is the national registry of the .pl domain.

"In past few days, Spamhaus has been in close contact with the sponsoring registrar (, the Polish Computer Emergency Response Team ( to get the domain names suspended," Morrison blogged Jan. 19. "In cooperation with the Polish CERT and the registrar, we managed to get all the Virut domain names within the .pl ccTLD sinkholed."

"In addition, Spamhaus reached out to the Austrian CERT and the Russian-based Company Group-IB CERT-GIB to shut down the remaining Virut domains within the .at and .ru ccTLDs," he added. "In cooperation with Spamhaus, and due to the evidence and intelligence provided by Spamhaus, CERT-GIB was able to shut down all the Virut domains within the .ru ccTLD within a few hours."

According to Morrison, the last remaining "stronghold" for the Virut command and control domains is the .at ccTLD.

"Having alerted both and the Austrian CERT multiple times about this issue we hope that they can soon follow the examples set by the work done with .pl and .ru," he blogged.

L. Aaron Kaplan of the Austrian CERT team told eWEEK that the team was contacted yesterday by the Polish CERT and is working on the issue.

Recently, researchers at Symantec noted that the Virut botnet was also distributing the Waledac malware, which the security company described as evidence of both how malware groups use affiliate programs to spread threats and how different pieces of malware can co-exist on the same system. In the past, Virut has also been used to spread the Zeus malware as well.

"At this time, Virut appears to be largely crippled, but the attackers are still in control of the botnet," Symantec's Security Response team told eWEEK. "While the efforts taken to stop the botnet should be lauded, other worldwide CERTS, registries and registrars must follow the example set today in order for a completely effective response and extermination of these threats to take place."

All totaled, NASK has seized control of more than three dozen domain names tied to Virut in the past week. At this time, Symantec said it has seen no signs of anyone trying to resuscitate Virut's infrastructure. Just how long Virut will remain down, however, is yet to be seen, Morrison noted.

"The Virut takedown effort clearly illustrates the important and meaningful role registries and registrars can play in the fight against cybercrime in general," he blogged. "Domains often are a critical part of malicious infrastructure. And by being proactive, their efforts can contribute a lot to online safety. We [therefore] urge registries and registrars to add clauses to the registration contracts that allow them to take action in cases where the domains involved are clearly only used for bad purposes."