Zero-day vulnerability in Microsoft Word under active attack

Attackers are exploiting a newly discovered vulnerability in Microsoft Word that makes it possible to remotely seize control of computers, the company warned.

The in-the-wild attacks work by creating booby-trapped documents in the Rich Text Format (RTF) that exploit a vulnerability in the 2010 version of Microsoft Word, Microsoft warned in an advisory published Monday. Similar attacks work against other versions of Word, including 2003, 2007, and 2013 for Windows, Microsoft Office for Mac 2011, and multiple versions of Microsoft SharePoint Server. E-mails that are viewed or previewed using a default setting in Outlook allow the attacker to gain the same system privileges as the user who is currently logged in.

"Microsoft is aware of a vulnerability affecting supported versions of Microsoft Word," Monday's advisory stated. "At this time, we are aware of limited, targeted attacks directed at Microsoft Word 2010. The vulnerability could allow remote code execution if a user opens a specially crafted RTF file using an affected version of Microsoft Word or previews or opens a specially crafted RTF e-mail message in Microsoft Outlook while using Microsoft Word as the e-mail viewer."

The advisory credited Drew Hintz, Shane Huntley, and Matty Pellegrino of the Google security team with discovery of the RTF memory corruption bug, which is formally cataloged as CVE-2014-1761. Microsoft has issued a temporary fix that configures Microsoft Office to prevent the opening of RTF files in supported versions of Microsoft Word. Users can also protect themselves against exploits by viewing e-mails in plain text. Monday's advisory said Microsoft may issue a permanent patch once an investigation into the vulnerability is completed.

The Microsoft advisory didn't say exactly who was being subjected to the attacks. The term "targeted attacks" is typically used to describe hacks that are directed against a specific individual or group of individuals, often as part of espionage campaigns targeting corporations or government agencies.

Post updated in the second paragraph to make clear not just version 2010 is vulnerable.