The advertising server of The Pirate Bay has been hacked and exploited to spread viruses and trojans among users of the site. The hackers targeted a vulnerability in the site's software to offload the malicious files, causing sections of The Pirate Bay to be blocked by Google, Firefox and several virus scanners.

With millions of visitors a day, torrent sites are a great outlet for spammers and scammers and others with malicious intent. Most recently, The Pirate Bay suffered from an attack by hackers who used an exploit in the site’s ad-server to offload malicious files.

A few hours ago, certain sections of The Pirate Bay were flagged by Google as containing malware and were subsequently blocked. Similar warnings were shown by Firefox and some virus scanners. Although The Pirate Bay didn’t host any malicious files, the site’s ads were pointing to several trojans and exploits.

These ads were not sanctioned by The Pirate Bay but were planted there by hackers who used an exploit in The Pirate Bay’s ad server to spread the files. The Pirate Bay ad server is running on OpenX, a popular ad serving platform based on phpAdsNew, which apparently has some unpatched vulnerabilities. Several other large sites that are using OpenX have reported similar problems recently.

The malicious ads found on The Pirate Bay in the last day were linking to external domains including cltomedia[dot]info where several trojans and exploits are hosted. As a result of the hack, Google, Firefox and various virus scanners listed The Pirate Bay as a malicious site, warning users who try to access it.

Frequent visitors to The Pirate Bay may recall that this is not the first time that the site has been flagged in this manner. Similar warnings have been issued several times before, and every time these were related to malicious ads. As it is the only part of the site where third parties have access to, this seems to be the most vulnerable element.

The Pirate Bay team informed TorrentFreak that they are currently working on resolving the problem. The vulnerabilities are expected to be fixed today and after a reinstall the world’s most popular torrent site should be working fine again. At the time of publishing, the warning by Google and others have already been lifted, but caution is advised.