Pirated copies of Windows 7 Release Candidate (RC) on file-sharing sites contain malware, according to users who have downloaded the upgrade.Windows 7 RC, which Microsoft Corp. will officialy launch tomorrow, leaked two weeks ago, with copies first appearing on BitTorrent tracking sites on April 24.Some of the pirated builds include a Trojan horse, numerous users said in message forums and in comments on BitTorrent sites such as Mininova.org."Just a warning for anyone downloading the new RC builds of windows 7. Quiet [sic] a lot of the downloads have a trojan inbedded [sic] in the setup EXE," said someone identified as Frank Fontaine on a Neowin.net discussion thread. "The Setup EXE is actually a container, it appears to be a self-extracting EXE. There are 2 files inside, Setup.exe and codec.exe."Fontaine's antivirus software identified the "codec.exe" file as a generic Trojan."Suspicious codec.exe!" reported someone labeled as "UltimateGTR" on Mininova, commenting on one of the 32-bit builds.Another Mininova commenter, "WuNgUn," identified the malware as the "Falder" Trojan, which downloads fake security software, dubbed "scareware," to PCs and installs a rootkit to hide from legitimate antivirus products.Microsoft, which has cited potential infection as a reason to steer clear of unauthorized downloads, jumped on the news. "This unfortunately shows that there are those out there who see the significant interest in something such as Windows 7 as an opportunity to try to take advantage of others," said Alex Kochis, director of Microsoft's Genuine Windows anti-piracy technology group, in a post to a company blog on Friday.Windows 7 RC is not the first leaked software found to harbor attack code. In January 2009, for example, security experts warned that pirated copies of Apple Inc.'s then-new iWork '09 suite contained a Trojan horse that hijacked Macs.Microsoft will let the general public download Windows 7 RC on Tuesday, but has not said what time it will make the upgrade available. Subscribers to TechNet and the Microsoft Developers Network (MSDN) have been allowed to download the RC since last Thursday.