Another outlet for the group, posting on Twitter as "Anonymous", wrote: "We are not responsible for other people's lack of common sense. We repeatedly posted Anon-OS is not to be trusted".

Graham Cluley, senior technology consultant for security vendor Sophos, wrote on the company's that while the company hasn't analyzed the code, "it wouldn't be a surprise if there was a Trojan element sneaked into Anonymous OS".

On Thursday, the Tumblr.com blog promoting Anonymous-OS appeared to deny that the software contained malicious code, posting the results of a scan for on Pastebin that showed it allegedly showed it was free of rootkits.

SourceForge said Anonymous-OS appears to be security related with an "attack-oriented emphasis," but the organization typically doesn't pass judgment on projects. SourceForge said it runs the risk of wrongly classifying a project as malicious, and it doesn't want to forfeit the trust of the developer community.

But "we believe this is the right decision in this case," the group said.