The cybercriminals behind ZeroAccess, one of the largest botnets in existence, have lost access to more than a quarter of the infected machines they controlled because of an operation executed by security researchers from Symantec.
According to Symantec, the ZeroAccess botnet consists of more than 1.9 million infected computers and is used primarily to perform click fraud and Bitcoin mining in order to generate revenues estimated at tens of millions of dollars per year.
ZeroAccess has a peer-to-peer architecture where every infected computer can relay files, instructions and information to other computers?peers?in the botnet. This mechanism is used by its operators for command and control (C&C), making ZeroAccess more resilient to takedown attempts than botnets that depend on dedicated C&C servers.
Earlier this year, security researchers from Symantec found a practical way to liberate ZeroAccess bots from the botmasters by leveraging a known design weakness in the peer-to-peer mechanism.