A joint international operation led by Europol and assisted by Microsoft, Symantec, and Anubis Networks has claimed success in clamping down on a cybercrime group suspected of deploying the Ramnit botnet for malicious purposes.

Ramnit is one of the world's biggest botnets, believed to have infected up to 3.2 million computers worldwide. A botnet is a network of subservient computers which operate under criminal control to spread viruses or send out spam containing malicious links.

Cybercriminals deployed Ramnit to gain remote access and control of computers infected by the malware, allowing them to disable antivirus protection and steal personal and banking information from people.

Police from Germany, Italy, the Netherlands, and the UK have seized the servers controlled by the group behind Ramnit in a bid to suppress its use.

"This successful operation shows the importance of international law enforcement working together with private industry in the fight against the global threat of cybercrime," said Wil van Gemart, Europol's deputy director of operations.

"We will continue our efforts in taking down botnets and disrupting the core infrastructures used by criminals to conduct a variety of cybercrimes," he continued.

The group behind Ramnit has been operating for at least five years. The botnet first reared its head in 2010 as a generic worm, but it quickly evolved due to what Symantec dubs its "aggressive self-propagation tactics" in a blog post.

In its earliest manifestations, the botnet would attempt to infect any EXE, DLL, HTM, and HTML files on the local hard disk and any removable drives, according to Symantec's blog post. But controllers quickly diversified the botnet's infection methods, borrowing modules from the Zeus Trojan malware to make Ramnit a fully fledged cybercrime tool capable of compromising victims in numerous ways.

Featuring six standard modules such as "Spy module," "Cookie grabber," and "Anonymous FTP server," Ramnit is able to steal website cookies and bank details, as well as monitor Web browsing sessions.

Back in 2012, Ramnit, which was dubbed "part virus, part botnet" by Ars Technica, succeeded in stealing at least 45,000 Facebook logins. Europol and industry partners involved hope that the recent crackdown will set back the cyber gang's operations.

Those concerned for the well-being of their computers are advised to seek information on www.getsafeonline.org or www.cyberstreetwise.com.

This story originally appeared on Wired UK.