Microsoft Issues Out of Cycle Fix for Zero Day Bug in Internet Explorer

The presence of a zero day security flaw in Internet Explorer 10 and Internet Explorer 9 has caught the attention of Microsoft, which decided to release a temporary patch rather than let it loom until next month's Patch Tuesday. According to Microsoft, the vulnerability doesn't exist in Internet Explorer 11, nor does it affect IE versions prior to 9.

"The vulnerability is a remote code execution vulnerability. The vulnerability exists in the way that Internet Explorer accesses an object in memory that has been deleted or has not been properly allocated," Microsoft explained in a security advisory. "The vulnerability may corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user within Internet Explorer. An attacker could host a specially crafted website that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the website."

IE Meme

There have been two known attacks related to this particular flaw, one of which involved hackers using the U.S. Veterans of Foreign Wars website to deliver drive-by malware attacks. In that instance, hackers used malicious JavaScript code and an iFrame to target the zero day bug. Users who fell prey to the attack would receive a payload that downloads a backdoor ZxShell Trojan.

If you're running a version of IE that's affected by this bug, Microsoft recommends applying its "Fix It" solution titled "MSHTML Shim Workaround" to prevent exploitation. You can grab the Fix It solution direct from Microsoft.