Unofficial patches defend against further IE flaw

Take two

Two groups of security researchers have released unofficial patches designed to protect surfers against an outstanding Internet Explorer vulnerability in the absence of available security updates from Microsoft.

The Zeroday Emergency Response Team (ZERT), a new ad-hoc group of security pros that came to prominence with the release of an unofficial fix designed to address a Vector Markup Language (VML) component vulnerability in IE, released a patch designed to address a vulnerability in the browser's Active X controls last weekend.

Security consultancy Determina published a separate fix for the same security bug in the WebViewFolderIcon ActiveX component of IE. The security bug is unrelated to a (still unpatched) flaw in Microsoft's Direct Animation Path (daxctle.ocx) ActiveX control discovered last month.

Microsoft released an out of schedule patch to address the VML exploit, the subject of the majority of recent IE-based attacks, last week. The other security bugs in the browser remain open to attack.

The latest unofficial patches were released in response to the availability of exploit code targeting the WebViewFolderIcon IE vulnerability, which creates a means to inject hostile code even on fully patched Win XP systems.

Microsoft is working on a patch, currently scheduled for an October 10 release, as part of its regular Patch Tuesday update cycle. While conceding that a threat exists, Redmond reckons published exploits are mostly harmless.

"We are aware of websites attempting to use the reported vulnerability to install malware. Our investigation into these websites shows that, in most cases, attempts to install malicious software by exploiting this vulnerability fail," a security notice from Microsoft explains. ®