Microsoft pushed out a patch May 12 to give Office PowerPoint users a shield against ongoing attacks targeting a zero-day vulnerability.
The fix is part of the month's sole Patch Tuesday security bulletin-a massive patch for a total of 14 security issues in PowerPoint. The only flaw known to be under attack is a memory corruption vulnerability first brought to light in early April that could permit attackers to take complete control of a compromised system.
According to Microsoft's advisory, the bug is due to a problem that occurs when PowerPoint reads an invalid index value in a specially crafted PowerPoint file. The resulting error can corrupt memory and allow an attacker to execute arbitrary code.
So far, no active or reliable exploits of the vulnerability have been found for Office for Mac, and Microsoft Office 2007, 2008 for Mac, Microsoft Office PowerPoint Viewers, and Microsoft Works versions 8.5 and 9.0 do not contain the vulnerability.
The bulletin is only rated critical for PowerPoint 2000 Service Pack 3, as PowerPoint 2002 and later versions have a built-in feature that prompts a user to Open, Save or Cancel before opening a document.
The only bug that affects all products in the affected products list is CVE-2009-0224, another memory corruption vulnerability in the way PowerPoint handles specially crafted PowerPoint files.
Updates are not available for Office 2004 for Mac, Office 2008 for Mac, Open XML File Format Converter for Mac, Microsoft Works 8.5 or Works 9.0. According to Microsoft, the company went ahead with the bulletin because of the active exploits. The updates for the other applications are still in development and will be released when ready.
"It is the month of PowerPoint bugs," Dave Marcus, research and communications director at McAfee Avert Labs, said in a statement. "Vulnerabilities in Office applications have been a favorite attack method among cyber-crooks, especially in stealthy attacks that seek to steal high-value intellectual property. Trojan horse attacks often use rigged Office files that exploit vulnerabilities in the productivity suite."