Microsoft today patched 20 vulnerabilities in Word, Office, Windows, SharePoint Server, SQL Server and other products in its portfolio, including a critical bug in the company's popular Word program and another already used to attack the company's own online services.
Of Tuesday's seven security updates, one was labeled "critical," Microsoft's most-severe threat ranking, while the others were pegged as "important," the next-most-serious rating.
The critical update for Word affected all versions of Microsoft's word processor on Windows, including Word 2003, 2007 and 2010; Word Viewer, the add-on that lets users who don't own Word view and print documents; and Office Web Apps, the free online editions of Word, Excel, PowerPoint and OneNote.
All the security researchers Computerworld contacted Tuesday urged users to install MS12-064, the critical Word update, as soon as possible.
Of special note, they said, was that one of the two bugs in Word could be exploited if users simply viewed a malformed RTF (rich text file) document in Outlook 2007 or Outlook 2010, which rely on Word as their default editing engine.
"Word is set as the editor for Outlook, so if you preview [a malicious RTF document], boom ... you've been hacked," said Andrew Storms, director of security operations at nCircle Security.
Document preview was once a widely-used hacker tactic, but it has fallen out of favor. "We haven't seen any for a while, so it's interesting when something like this resurfaces," Storms said.
Jason Miller, manager of research and development at VMware, also tapped MS12-064 as the update that needed immediate attention, as did others, including Wolfgang Kandek, CTO of Qualys, and Marcus Carey, a security researcher at Rapid7.
"RTF documents are typically not blocked by company email servers," observed Miller. "Also, RTF documents, like PDF documents, are commonly used for sharing documents between different companies."
Although the remaining half-dozen bulletins -- Microsoft's term for its Patch Tuesday updates -- were all rated as only important, some researchers spotted intriguing characteristics that they said deserve users' attention.
"I'd pick MS12-066 next, after the Word update," said Storms, referring to the one-patch update that patches a bug allowing attackers to bypass SafeHTML's protection.
SafeHTML, which Microsoft calls "HTML sanitization," is a defense designed to protect users from cross-site scripting browser attacks.
Storms based his opinion about MS12-066 on Microsoft's admission that it had been targeted by attacks exploiting the vulnerability.
"We have seen limited, targeted attacks attempting to leverage this vulnerability against Microsoft online services," said Microsoft in a note on its Security Research & Defense blog. The company did not elaborate on what online services had been attacked.
"So there are already attacks in the wild, and Microsoft itself has seen limited attacks," said Storms.
Sign up for Computerworld eNewsletters.