What Is ZeroAccess?
The ZeroAccess rootkit is a Trojan infecting Windows operating systems. The malware is also known as max++ or Sirefef and was first detected in the summer of 2011. The ZeroAccess botnet is to this day one of the largest peer-to-peer (P2P) botnets. The number of infected machines so far is over two million PCs. The rootkit is reportedly present on more than nine million systems. The botnet is almost impossible to be disabled because no central command and control (C&C) server exists. Every time a PC gets infected with ZeroAccess, it reaches out to a few of its peers to exchange data about other peers in the known peer-to-peer network. This way the bots are informed about the other peers and are able to deliver instructions and files in a quick manner. The constant connection between the peers makes the exchange of peer lists and the search for update files possible. This, unfortunately, makes any attempt to take the botnet down almost pointless.
The ZeroAccess infection usually remains hidden in the system due to its rootkit capabilities and is mainly used for the following purposes:
- To download various malware on the affected machine.
- To form a botnet used primarily for Bitcoin mining or Click fraud.
Computers that are involved in Bitcoin mining generate Bitcoins for the person controlling them. The experts report that the profit from them amounts to $2.7 million per year. The PCs used for click fraud imitate clicks on online ads, which generate profit on a pay per click basis. The estimated worth for this particular activity may amount to $100,000 per day.
ZeroAccess’ Distribution Path
As a typical Trojan, ZeroAccess does not spread on its own. It is usually delivered through compromised websites that redirect the user to a malicious online location where the malware is distributed via the Bleeding Life Toolkit and the Blackhole Exploit Toolkit. Both of those toolkits exploit numerous vulnerabilities to enter the user’s system and infect it with ZeroAccess.
The ZeroAccess Botnet – Not Quite Dead Yet
Microsoft Corp. has recently combined efforts with European authorities in an operation to bring down ZeroAccess botnet. The experts though are not that optimistic in their estimate and believe the botnet is not fully eliminated. The threat is too complex to be completely destroyed, professionals say. This is Microsoft’s eight attempt to disrupt the botnet in the past three years.
The servers delivering the ZeroAccess malware were shut down during a joint operation of Microsoft, FBI and the European Cybercrime Center. The command over 49 domains associated with the botnet was taken during the campaign. This is a significant number that should cripple the ZeroAccess botnet for a while, but it will take more hard work to eliminate it completely. The profit generated for the botnet’s creators was reportedly $3 million a month.