Symantec issues critical alert for Windows flaw

Security vendor Symantec has raised the threat for the unpatched vulnerability in Microsoft Windows Meta File exploit to Level 3, the second most severe on its scale.

In a media statement released Wednesday, Symantec said "numerous malicious code programs including a worm, have been discovered exploiting this issue over various mediums, including the Web, e-mail and instant messaging".

The last time the security vendor issued a Level 3 alert via the Symantec ThreatCon warning classification was in July 2004, when MyDoom.M struck.

"Because a patch will not be available until Jan. 10, there is a seven-day window that attackers could exploit this issue in a potentially widespread and serious fashion," Alfred Huger, senior director at Symantec Security Response, said in the statement. "People should be very cautious about the Web sites they visit and the e-mail they receive over the next week."

Symantec added that users should consider turning off the preview feature on e-mail programs to avoid being infected, as well as deploy network intrusion detection products to monitor network traffic for malicious activity.

The vulnerability, discovered last week, affects Windows XP Service Pack 1 and 2, as well as Windows Server 2003, and has already spurred various attacks. Security expert F-Secure warned Tuesday that "99 percent of computers worldwide are vulnerable to this attack".

Antivirus vendor F-Secure and the Internet Storm Center, a volunteer security group, also urged businesses on Tuesday to use an unofficial patch--a proposal Microsoft has cautioned against.