Security Advisor

Microsoft Backtracks, Includes Windows XP in IE Zero-Day Patch

The fix comes on the heels of attackers actively exploiting the Internet Explorer Flash flaw against Windows XP users.

Microsoft this morning released an out-of-band patch for the Internet Explorer zero-day vulnerability that was disclosed earlier in the week.

What's significant about this fix is that Microsoft has made available a security update for Windows XP users well after official support for the OS has ended.

"We made this exception based on the proximity to the end of support for Windows XP," wrote Adrienne Hall, general manager of the Trustworthy Computing group at Microsoft in a blog post.  The reality is there have been a very small number of attacks based on this particular vulnerability and concerns were, frankly, overblown.  Unfortunately this is a sign of the times and this is not to say we don't take these reports seriously.  We absolutely do."

Also playing into Microsoft's reasoning for releasing a security fix for XP could be the fact that the Internet Explorer exploit has been recently used to attack Windows XP systems might have played into its decision.

When first announced, security firm FireEye -- the firm that first discovered and disclosed the flaw -- said that it had only seen attacks against Windows 7 and 8 users by exploiting the vulnerability in Internet Explorer 9, 10 and 11. But since its initial disclosure, the security firm has now seen attackers taking advantage of the flaw in Internet Explorer 8 to target Windows XP.

"The main differences between this new attack targeting Windows XP compared to the original Windows 7/8.1 versions of this attack are the mitigation bypasses," said FireEye's Dan Caselden in a post on the company's Web site.  "The Windows 7/8.1 version develops its write primitive into read/write access to much of the process space by corrupting Flash vector objects. This is to bypass ASLR by searching for ROP gadgets and building a ROP chain dynamically in memory."

Today's security patch release should close the hole in all versions of Microsoft's Web browser for all versions of its OS and users with automatic updates enabled won't need to take any actions. For those without automatic updates enabled, Microsoft recommends that users update their systems as soon as possible through the Microsoft Update service due to the active status of this vulnerability.

About the Author

Chris Paoli is the site producer for Redmondmag.com and MCPmag.com.

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