The Internet security firm Intego has just announced that it has discovered a new Trojan horse in pirated copies of Apple’s iWork ’09 productivity software, and this could allow an attacker to take control of the infected computer. The Trojan horse is known as SX.Trojan.iServices.A and it has been discovered circulating in copies of the software on BitTorrent trackers and other pirate sites.

According to Intego’s security alert, the worm is rated serious. How does the Trojan work? Well, when iWork is installed, this is also installed, as a start-up item, a part of iWorkServices. It has read-write-execute permissions for root control of the computer, and the malware connects to a remote server over the Internet, possibly downloading additional components to the infected computer.

According to Intego, as of Thursday, at least 20,000 people had downloaded the iWork ’09 installer. The Trojan could scan the infected Mac for sensitive information, track Internet activity, record logins and passwords and do just about anything nefarious thing the bad guy pulling the string wants.

From its home page, SecureMac is offering a free download, iWorkServices Trojan Removal Tool, which will practically remove the Trojan from compromised Macs. In an update to its original alert, Intego also reports that the Trojan horse is actively downloading new code and acting as a botnet, participating in distributed denial of service attacks on certain Web sites.

This confirms there are viruses for Macs too, as hackers are increasingly looking with greedy eyes at the Apple user community, a community which is acting much more recklessly when it comes to defending against malware than their Windows-using cousins. Even if Apple is known for a virus-resistant platform, in the 1980s and early 1990s, the Mac was among the top platforms for spreading malicious code. Security researchers recommend Mac users to stay protected with security software.