Hackers are shamelessly exploiting the festive season to spread malware.

A Christmas-themed jigsaw puzzle game called Christmas_Puzzle.exe doing the rounds is actually a Trojan (Ardamax-E) that uses rootkit technology to hide its presence on compromised systems.

Meanwhile a PowerPoint file named Christmas+Blessing-4.ppt uses an IE vulnerabilities to deposit malicious code on vulnerable Windows boxes. The exploit has been embedded in an innocent Christmas-themed PPT slideshow that's been circulating on the net, security firm F-Secure notes.

F-Secure has also received a malware file - named Christmas.exe - which displays a Christmas-themed image as a decoy for its real purpose, turning compromised machines into compromised zombie PCs under the control of hackers.

Not all this festive malware is related to Christmas.

F-Secure notes that a new Warezov spam run is underway which uses a "Happy New Year" postcard as its disguise. Windows users who run the infected attachment will find their PCs running malware that downloads a new variant of the infamous Warezov Trojan.

Standard defensive precautions against viral attacks apply in defending against these Xmas malware assaults.

Users are urged to patch systems up to date and update anti-virus signature definition files. Resisting the temptation to open unsolicited email attachments is also a good idea, of course.

Xmas hats from crackers made from tin-foil instead of paper might also be a good idea, if things get any worse. ®

Related stories

• MoD: Frontline troops must have silent Xmas crackers (10 December 2007)
• Malware: Windows is only part of the problem (10 January 2007)
• Mysterious drop in fraud and spam (9 January 2007)
• Happy New Malware (2 January 2007)
• Inside a cyber-crook's Xmas wish list (12 December 2006)
• Spam: now made in China (4 December 2006)
• T'is the season to be ripped off... (13 November 2006)
• Santa worm is coming to IM (22 December 2005)
• Cybercrims target Xmas shoppers (14 December 2005)