Critical and unpatched, Windows XP bug is under attack

Red meat for full disclosure critics

Five days after it was disclosed in a highly controversial advisory, a critical vulnerability in Microsoft's Windows XP operating system is being exploited by criminal hackers, researchers from anti-virus provider Sophos said on Tuesday.

The flaw in the Windows Help and Support Center was disclosed on Thursday by researcher Tavis Ormandy. His public advisory came just five days after he privately informed Microsoft of the defect, prompting fierce criticism from some circles that he hadn't given the software giant adequate time to fix the hole. That made it easier for attackers to target the bug, which allows attackers to take complete control of vulnerable machines when a user views a specially designed webpage, the critics howled.

According to Sophos, researchers have seen the first case of a website using the vulnerability to install malicious software on victim machines. “This malware downloads and executes an additional malicious component (Troj/Drop-FS) on the victim’s computer, by exploiting this vulnerability,” they warned.

Microsoft soon amended its own advisory on the vulnerability to say researchers are “aware of limited, targeted active attacks that use this exploit code.” Although the vulnerability also afflicts Windows Server 2003, Microsoft's advisory said that OS wasn't “currently at risk from these attacks.”

Ormandy's advisory has reignited the age-old debate over full disclosure, in which researchers publish complete details of a vulnerability under the belief that it is the best way to ensure a company fixes it quickly. Ormandy has defended his decision to give Microsoft just five days of advanced warning saying in a recent tweet: “I'm getting pretty tired of all the '5 days' hate mail. Those five days were spent trying to negotiate a fix within 60 days.”

Users of XP and Server 2003 should consider disabling features within Help Center that allow administrators to remotely log onto machines. For individual users, the easiest way to do this is to use the online “Fixit” application Microsoft has provided here. ®

Sponsored: Driving business with continuous operational intelligence