Intego, a maker of anti-virus and firewall software, has issued an alert to warn Mac users not to download Apple iWork ’09 installers from sites offering pirated software.

The risk of infection is serious, and users may face extremely serious consequences if their Macs are accessible to malicious users says Intego.

Intego reports at least 20,000 people have already downloaded this installer.

The OSX.Trojan.iServices.A Trojan Horse was discovered on Wednesday 21 January, and is classed as ‘serious’ by Intego.

The version of iWork ’09 is reportedly currently available on BitTorrent tracker sites and popular ‘warez’ websites and forums.

Once downloaded iWork ’09 is complete and functional, but the installer contains an additional package called iWorkServices.pkg says Intego.

The Intego alert explains what happens next.

“When installing iWork 09, the iWorkServices package is installed. The installer for the Trojan horse is launched as soon as a user begins the installation of iWork, following the installer’s request of an administrator password (in older versions of Mac OS X, 10.5.1 or earlier, there will be no password request).”

“This software is installed as a startup item (in /System/Library/StartupItems/iWorkServices, a location reserved normally for Apple startup items), where it has read-write-execute permissions for root.”

“The malicious software connects to a remote server over the Internet; this means that a malicious user will be alerted that this Trojan horse is installed on different Macs, and will have the ability to connect to them and perform various actions remotely. The Trojan horse may also download additional components to an infected Mac.”

Earlier this week Apple removed the need to enter a serial number when iWork ’09 is purchased boxed, leading some to speculate the company abandoning anti-piracy measures.

More details can be found on the Intego blog.

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