A company that makes security software for Mac computers is warning that copies of Apple’s iWork productivity software that are available for download from peer-to-peer (P2P) file-sharing networks may be infected with a Trojan horse program. The malicious software appears to be designed to enlist infected systems in a bot army that is targeting Web sites with so much junk traffic they can no longer accommodate legitimate visitors. In an alert issued today, Intego said some pirated versions of the $79 iWork software suite circulating on BitTorrent trackers are infected with what it calls OSX.Trojan.iServices.A. Intego said the Trojan is bundled so that it runs when the user installs the pirated iWork software. iServices.A then opens up a “backdoor” on the victim’s computer, effectively alerting the virus writer that a new system is infected and potentially allowing the attacker to upload new software to or perform other actions on the