A new worm that purports to offer steamy pictures of Brad Pitt and Angelina Jolie contains a payload targeted at Microsoft.

Ahker-F arrives as an attachment called Clip.zip in emails with the header: 'Watch Angelina Jolie and Brad Pitt cought [sic] on TAPE! SEXY CLIP! WATCH IT!'.

Once activated the worm copies itself onto the user's hard drive, attempts to shut down any antivirus software on the computer and tries to spread using email, IRC and P2P systems.

Ahker-F also tries to launch a denial of service attack against Microsoft's Windows Update service and a software company called Rohitab.com.

"People's appetite for salacious gossip is insatiable, and some may be tempted to run what appear to be pornographic movie files distributed across the internet," said Graham Cluley, senior technology consultant at Sophos.

"However, virus writers have a long history of disguising their malicious code as this kind of content. Everyone should be very careful about what they choose to run on their computer."

This is the sixth Ahker worm, all of which seem to come from the same virus writer who calls himself 'Agent Hacker'.

In this version the writer includes the following messages for the antivirus vendors: "Agent Hacker rules!" and "Genes don't contain any record of humain [sic] history, you'll NEVER catch me!(Agent Hacker - Bazzi."

Computer users are warned to be on their guard and to update virus signatures regularly.