Symantec reports that
[...] In the wake Anonymous member arrests this week, it is worth highlighting how Anonymous supporters have been deceived into installing Zeus botnet clients purportedly for the purpose of DoS attacks. The Zeus client does perform DoS attacks, but it doesn’t stop there. It also steals the users’ online banking credentials, webmail credentials, and cookies.
[...] The deception of Anonymous supporters began on January 20, 2012, the day of the FBI Megaupload raid. An attacker took a popular PasteBin guide, used by Anonymous members for downloading and using the DoS tool Slowloris, and modified it. In this modified version, the attacker changed the download link to a Trojanized version of the Slowloris tool with matching text
[...]
Not only will supporters be breaking the law by participating in DoS attacks on Anonymous hacktivism targets, but may also be at risk of having their online banking and email credentials stolen. The joining of malicious financial and identity fraud malware, Anonymous hacktivism objectives, and Anonymous supporter deception is a dangerous development for the online world.
Always be careful what you download. Think twice before participating in ‘campaigns’ against ‘the Man’. You can’t trust anyone on the Internet.