Microsoft on Tuesday beefed up security in Office 2003 and Office 2007 on Windows by adding a feature that first appeared in the newer Office 2010 last year.
In Office 2010, the security feature, labelled Office File Validation (OVE), examines older pre-XML file formats for Word, Excel, PowerPoint and Publisher, then opens those that don't conform to the documented format in a special "sandbox" called Protected View.
One recent example: rigged Word documents that include a malicious Flash file exploiting Abobe's newest zero-day bug are shunted to the Protected View sandbox in Office 2010.
This week, Microsoft made good on a promise last year to bring one part of OVE to Office 2003 and Office 2007.
Users of those suites can download and install an update that triggers an alert when Word, Excel, PowerPoint or Publisher tries to open a potentially dangerous file. Alerts are the extent of the new feature, since neither Office 2003 nor Office 2007 includes a sandbox.
Although users can click through the warning to continue opening the file, enterprise IT administrators can block that by using Group Policy settings, said Jerry Bryant, group manager with the Microsoft Security Response Center (MSRC).
Microsoft is making the OVE update optional for now.
"It's a big functionality change, especially to enterprises," said Bryant, who added that Microsoft decided it was best to not offer OVE via the Microsoft Update service, so as to give companies time to test the feature.
Bryant declined to commit to a timetable for pushing the Office 2003 and Office 2007 updates through Microsoft Update. However, the Office team said that OVE would be available via Microsoft Update "in the near future."
Security experts applauded the decision to "backport" OVE to older editions of Office.
"What's interesting is that it stops the upgrade bandwagon," said Andrew Storms, director of security operations for nCircle Security. "Backporting [OVE] is a real recognition by Microsoft that they're hearing from customers who want this protection. They're essentially giving users a free feature."
Wolfgang Kandeck, chief technology officer of Qualys, urged all Office 2003 and Office 2007 users to install the OVE update. "We think it should be mandatory," said Kandek.
Rodrigo Branco, the director of vulnerability research at Qualys, also chimed in with a recommendation. "[OVE] captures many of the more obvious attacks based on Word, PowerPoint and Excel documents," said Branco, who reported one of the nine Excel vulnerabilities that Microsoft patched Tuesday in a record security update.
Office XP, which is nearing the end of its support lifecycle, isn't eligible for the OVE update.
The 3MB OVE update can be downloaded from Microsoft's site.