The most recent domain name sold through Reg.ru was added to Zeus Tracker on Wednesday. That server temporarily hosted two kinds of Zeus files that have since been removed. It is possible that the owner of that domain discovered the infection and then removed the offending files.
A Reg.ru spokeswoman said that the company would look into those domains. Reg.ru, which is run out of Russia, "always promptly reacts" to inquiries or complaints from third-parties or law enforcement agencies, she said.
The issue highlight the difficulties security researchers and law enforcement have in trying to tackle botnets, which have been purposely built to be robust and redundant, much like how corporations structure their own IT systems.
But the security community has had some success in weakening and nearly wiping out botnets, but it has taken highly coordinated efforts.
Earlier this year, Microsoft petitioned a court to compel VeriSign, the .com registry, to remove 277 ".com" names from its rolls. That action cut off communication between the Waledac botnet's C&Cs and its infected troupe of computers.
Simultaneously, Microsoft recruited a team of crack computer security researchers who were able to infiltrate Waledac's peer-to-peer control system and command those infected machines to report to their own servers, cutting the cybercriminals off from their own botnet.
It doesn't appear that there are similar efforts under way to do a technical take down of Zeus to coincide the arrests. And to mount one would be difficult, said Thorsten Holz, an assistant professor of computer science at Ruhr-University in Bochum, Germany, who participated in the Waledac action.
Since criminal groups can license the Zeus software from its development group, they can set up their own C&Cs, Holz said.
"This leads to the huge number of C&Cs, which in turn render Zeus take downs in a coordinated fashion pretty hard," Holz said. "And even if many of the current C&Cs are taken down, new groups will likely emerge that run new C&Cs.
"Nevertheless the arrests are a good signal in my humble opinion since they show that there are investigations in this area which are successful," he said.
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