Microsoft admitted to vulnerability in its Jet Database Engine after a series of attacks on Word files have been reported. The issue doesn’t affect customers using Windows Server 2003 Service Pack 2, Windows Vista and Windows Vista Service Pack 1, whose Microsoft Jet Database Engine is not confronted with this problem.

On the other hand, those using Microsoft Word 2000 Service Pack 3, Microsoft word 2002 Service Pack 3, Microsoft Word 2003 Service Pack 2, Microsoft Word 2003 Service Pack 3, Microsoft Word 2007 Service Pack 1 on Microsoft Windows 2000, Windows XP or Windows Server 2003 Service Pack 1 are vulnerable to these attacks, the company said.

“Do not open or save Word files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted Word file,” the company said in an advisory, suggesting customers to use Protect Your PC, enable a firewall and install updated antivirus software.

How this vulnerability expresses itself in reality is not complicated: the attack uses Word files to import external data. Microsoft already announced that the threat is real for PCs with older versions than Msjet40.dll 4.0.9505.0 and that they are already working on an update to prevent such malicious attacks from happening.

Bill Sisk said in a blog on MSRC (the Microsoft Security Response Center): “We’ve activated our Software Security Incident Response Process (SSIRP) to investigate the vulnerability (…) As part of our SSIRP process, we currently have teams working to develop an update of appropriate quality for release (…) In the meantime, we encourage customers to view the advisory and implement the workarounds.”

The company said reports to the attacks have been limited so far and that “current attacks require customers to take multiple steps in order to be successful; we believe the risk to be limited,” Microsoft said.