Posts Tagged: KB2757760


19
Sep 12

Microsoft Issues Stopgap Fix for IE 0-Day Flaw

Microsoft today released a stopgap fix for a critical security flaw in most versions of Internet Explorer that hackers have been exploiting to break into Windows systems. The company said it expects to issue an official patch (MS12-063) for the vulnerability on Friday, Sept. 21.

The company released a “fix it” tool, available from this link, designed to blunt the threat of attack on this flaw for users of IE 7, 8 and 9. In a blog post, Microsoft’s Yunsun Wee said the one-click solution should not affect users’ ability to browse the Web, and it does not require the reboot of your computer. Users should not need to uninstall the fix to apply the full security patch when Microsoft releases it.

I’m glad to see Microsoft take this step. The company keeps downplaying the threat, stating that “there have been an extremely limited number of attacks,” against that this flaw and that “the vast majority of Internet Explorer users have not been impacted.” Nevertheless, as I noted in previous stories this week, a reliable exploit for this vulnerability has already been rolled into free, easy-to-use attack tools, so IE users should not delay in applying this fix-it tool.

For more information on how to harden IE against attacks, see Internet Explorer Users, Please Read This.


18
Sep 12

Internet Explorer Users: Please Read This

Microsoft is urging Windows users who browse the Web with Internet Explorer to use a free tool called EMET to block attacks against a newly-discovered and unpatched critical security hole in IE versions 7, 8 and 9. But some experts say that advice falls short, and that users can better protect themselves by surfing with an alternative browser until Microsoft issues a proper patch for the vulnerability.

The application page of EMET.

EMET, short for the Enhanced Mitigation Experience Toolkit, is a tool that can help Windows users beef up the security of commonly used applications, whether they are made by a third-party vendor or by Microsoft. EMET allows users to force applications to use one or both of two key security defenses built into Windows Vista and Windows 7 — Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP).

Put very simply, DEP is designed to make it harder to exploit security vulnerabilities on Windows, and ASLR makes it more difficult for exploits and malware to find the specific places in a system’s memory that they need to do their dirty work.

Before I get into the how-tos on EMET, a few caveats. EMET is a great layer of security that Windows users can and should use to enhance the security of applications. But EMET may not block the exploit code now publicly available through the Metasploit framework. In fact, Tod Beardlsey, an engineering manager with Rapid7, the security firm that manages Metasploit, told The Associated Press that EMET does not appear to be completely effective against this exploit.

I asked Metasploit founder HD Moore what he thought was the best way to block this exploit, and he pointed out that the exploit available through Metasploit requires the presence of Java on the host machine in order to execute properly on IE 8/9 on Windows 7 and Vista systems (the exploit works fine without Java against IE7 on XP/Vista and IE8 on XP). Obviously, while the lack of Java on a Windows machine may not prevent other exploits against this flaw, it is a great first start. I have consistently urged computer users of all stripes to uninstall Java if they have no specific use for it.

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