Word security flaw lets attackers take over PCs

A new bug has been found in Word 2003 and Word XP

A newly found flaw in Microsoft Word could allow hackers to execute code on Windows PCs and even take control of them. Security firm Symantec said it had already detected attempts to exploit the bug to install backdoor Trojan software on systems.

The US Computer Emergency Readiness team (US-Cert) has issued an alert detailing the flaw. It stated that the attack, labelled Trojan.Mdropper.H by Symantec, affects Microsoft Word 2003 and Word XP.

When users open a specially crafted document, a buffer overflow allows the attacker to execute arbitrary code. If the user has administrative privileges, US-Cert warned, the attacker could gain complete control of the system.

Symantec has given the vulnerability a low severity rating, as it relies on tricking users into opening a file in order for the attack to be successful.

Microsoft said in a statement that it was working on an update to address the vulnerability. This is scheduled to be released as part of the firm’s monthly security update due on June 13, but may be released sooner if warranted.

Symantec said it had detected attempts to use the Word flaw to infect systems with Backdoor.Ginwui, a malicious program that opens up a user’s computer to further attacks.

“This threat originated in Asia but is not spreading widely because it seems to be targeted at specific large organisations,” said Vincent Weafer, senior director of Symantec Security Response. He added that the event illustrates the trend toward zero-day targeted attacks.

Experts said that that the flaw supported the argument for restricting the privilege level of ordinary users, as the attack fails unless the user has administrator privileges.