Security researchers have uncovered the command and control network of a Zeus 2 botnet sub-system targeted at UK surfers that controlled an estimated 100,000 computers.
Cybercrooks based in eastern Europe used a variant of the Zeus 2 cybercrime toolkit to harvest personal data - including bank log-ins, credit and debit card numbers, bank statements, browser cookies, client side certificates, and log-in information for email accounts and social networks - from compromised Windows systems.
Trusteer researchers identified the botnet's drop servers and command and control centre before using reverse engineering to gain access its back-end database and user interface. A log of IP addresses used to access the system, presumably by the cybercrooks that controlled it, was passed by Trusteer onto the Metropolitan Police.
Trusteer declined to point the finger as to the locations of the Zeus botmaster controlling the systems, beyond saying that compromised systems were controlled from eastern Europe.
"The cybercrime servers were hidden but the hackers were not using a lot of security, so it was possible to find a way into the database," Mickey Boodaei, Trusteer's chief exec told El Reg.
The original attack was probably seeded by a combination of infected email attachments and drive-by downloads, according to Amit Klein, Trusteer's chief technology officer. The Windows-based malware used to control zombie clients was a variant of the infamous Zeus cybercrime toolkit, a customisable Trojan keylogger and botnet-control client sold through underground forums that's become the sawn-off shotgun of the cybercrime economy over recent years.
"There are some significant changes between Zeus 1.x and Zeus 2.0: Zeus 2.0 installs differently, better adapted to newer Windows operating systems (Vista, 7). Additionally, Zeus 2.0 has built-in support for Firefox," Klein explained.
"There are Zeus binaries out there for few months already with version number 2.0.x.y. We do not control Zeus's version numbers - it's the Zeus writers who do that," he added.
Trusteer says the attack is an example of the growing trend of regionalised malware. ®