Researchers at AVG have uncovered a botnet that has been harvesting personal information and uses the latest version of the Zeus code, underscoring the widespread use of the sophisticated malware.
Dubbed the Mumba botnet, the campaign infected more than 35,000 computers when it started at the end of April, according to a white paper released by AVG.
The botnet has now collected at least 60GB of information from some 55,000 computers, half of which are in the UK and Germany, according to an analysis of a server used to collect the data, which included credit card numbers, email, login and password information for social-networking sites and bank account details.
Mumba uses at least four variants of Zeus to spy on computers. Zeus is a well-known piece of malware can send spam, steal financial or other data or conduct a distributed denial-of-service attack against other computers.
Its creators have developed a toolkit that they can sell to lesser technically skilled cybercriminals that makes it easier to use and manage infected computers. The latest Zeus version, 184.108.40.206, supports the Windows 7 operating system and can also steal HTTP traffic data from the Firefox browser, AVG said.
The Mumba botnet is believed to be controlled by the Avalanche Group, which specialises in phishing sites as well as malware, AVG said.
To hide how they control the botnet, Mumba's operators are using a technique called fast flux, which allows an administrator to quickly point a domain name to a new IP address. It is a redundancy mechanism that is designed to allow high-traffic Web sites to manage traffic, but it is also being abused by cybercriminals to make their command-and-control system much harder to shut down.
"The 'Mumba' botnet is probably one of the first to use the Avalanche operation in order to host its stolen goods as well as the malware infection," the white paper said. "This seems to be yet another step in the never ending arms race between the security industry and cybercriminals."