ZeroAccess is a hugely widespread malware threat that has plagued individuals and enterprises for years. It has evolved over time to cater for new architectures and new versions of Windows.
Here at SophosLabs we have looked at previous incarnations of the ZeroAccess rootkit in depth, describing how it enslaves victim PCs, adding them to a peer-to-peer botnet which can receive commands to download further malware.
Most recently, Sophos's researchers explored how ZeroAccess took a major shift in strategy, operating entirely in user-mode memory.
Due to the continued high profile of this malware family we felt it was necessary to examine the threat in greater detail, not only the latest version of ZeroAccess, but also the ZeroAccess botnet as a whole.
SophosLabs researchers can reveal that the current version of ZeroAccess has been installed on computers over nine million times with the current number of active infected PCs numbering around one million.
ZeroAccess uses a peer-to-peer network to download plugin files which carry out various tasks designed to generate revenue for the botnet owners. Our researchers monitored this network for a period of two months to discover where in the world the peers were located and what kind of files the botnet was being instructed to download.
We found the IP addresses of infected machines from a total of 198 countries ranging from the tiny island nation of Kiribati to the Himalayan Kingdom of Bhutan, as can be seen when the infected machines are plotted on a world map:
The largest numbers of infected computers were found in the USA, Canada and Western Europe:
Our research has discovered that the ZeroAccess botnet is currently being used for two main purposes: Click fraud and Bitcoin mining.
If running at maximum capacity the ZeroAccess botnet is capable of making a staggering amount of money: in excess of $100,000 a day.
We have also reverse-engineered the mechanisms by which the ZeroAccess owners keep tabs on the botnet, and discovered an array of techniques used that are designed to bury the call-home network communications in legitimate-seeming traffic.
You can find out much more about ZeroAccess in our new technical paper - "The ZeroAccess Botnet - Mining and fraud for massive financial gain".Follow @SophosLabs
Snake in the shape of a zero image from Shutterstock.