Hackers target zero-day Windows vulnerability

Microsoft has issued a security advisory warning about an unpatched security hole in Windows that is actively being exploited by online criminals. 

Attackers are using a flaw in the way that Windows handles the .wmf (Windows Metafile) graphic file format. A specially crafted .wmf image placed on a website or sent through a spam email could allow the criminal to execute code on a user's system.

The arbitrary code execution lets the attacker install spyware or recruit a system for a zombie network, a collection of computers used for online crimes including sending spam or launching distributed denial of service attacks.

Microsoft urged users to update their antivirus software, and said that it is investigating the issue.

A patch is being developed which will be released either through Microsoft's monthly patch cycle on the second Tuesday of the month or as an out-of-cycle security update.

Security firm Secunia gave the vulnerability its highest severity ranking of 'extremely critical'.

Security firm F-Secure said on its blog that it has seen at least three different computer worms that exploit the security hole. The company refers to the worms as W32/PFV-Exploit.A, .B and .C. The threats are being spread by spam email messages and through several websites.

Users of Microsoft's Internet Explorer are automatically infected when they visit a webpage hosting an infected image. Firefox will first ask the user before opening the file. If the user approves, the PC will be infected.

The US Computer Emergency Readiness Team described several workarounds on its website that will mitigate but not eliminate the risk until Microsoft releases a patch.

The workaround includes avoiding .wmf files from untrusted sources and resetting the file association, or opening the files with an application other than Windows Picture and Fax Viewer.

See also:

Internet worm catches child porn surfer

Malware inadvertantly does something good for a change  21 Dec 2005

Christmas worms target Microsoft

Unwelcome present from China  16 Dec 2005

Experts crack Sober worm code

Expect a major global outbreak on 5 January  09 Dec 2005

Intelligent worm 'chats' to IM users

First virus that answers back  07 Dec 2005

November breaks all malware records

Trojans overtake email viruses as organised crime gets more involved  06 Dec 2005

Hackers could worm into Apple's QuickTime

Four critical flaws hit popular media player  07 Nov 2005

Like this story? Spread the news by clicking below:

 del.icio.us     Digg this     reddit!