Microsoft has warned of a zero-day vulnerability in Word and limited, targeted attacks directed at the 2010 version.
In an advisory, Microsoft said that 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 email message in Microsoft Outlook while using Microsoft Word as the email viewer.
The vulnerability can be exploited through Microsoft Outlook only when using Microsoft Word as the email viewer. Microsoft Word is the email reader in Microsoft Outlook 2007, Microsoft Outlook 2010, and Microsoft Outlook 2013 by default.
Wolfgang Kandek, CTO at Qualys, said: “The vulnerability CVE-2014-1761 is in the file format parser for RTF (Rich Text Format) and could be used by an attacker to gain remote access to the targeted system. The attack vector is a document in RTF format that the victim would have to open with Word.
“The current workaround is to disable RTF as a supported format in Microsoft Office. The advisory contains a link to FixIt 51010 that performs the action for the end-user here. A secondary recommended action is to work with plain text in emails, which is generally a recommended safeguard that prevents the “drive-by” characters of these types of attacks,” he said.
Dana Tamir, director of enterprise security, said: “A web-based scenario can also be used if the attacker creates a webpage that contains the malicious RTF-file, or if the malicious file is provided as content to websites that accept or host user-provided content or advertisements.
“Attackers may use this technique for conducting drive-by downloads and watering-hole attacks that infect website visitors. Microsoft has posted a blog that discussed possible mitigations and temporary defensive strategies that can be used while Microsoft is working on a security update.”