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Security Response

Zero-Day Internet Explorer Vulnerability Let Loose in the Wild

Created: 27 Apr 2014 12:14:01 GMT • Updated: 02 May 2014 13:38:41 GMT • Translations available: 日本語, 한국어, Português, Español
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Symantec is aware of reports of a zero-day vulnerability, Microsoft Internet Explorer Remote Code Execution Vulnerability (CVE-2014-1776), that affects all versions of Internet Explorer.

Microsoft released a security advisory on a vulnerability in Internet Explorer that is being leveraged in limited targeted attacks. There is currently no patch available for this vulnerability and Microsoft has not, at the time of writing, provided a release date for one.

Our testing confirmed that the vulnerability crashes Internet Explorer on Windows XP. This will be the first zero-day vulnerability that will not be patched for Windows XP users, as Microsoft ended support for the operating system on April 8, 2014. However, Microsoft stated that its Enhanced Mitigation Experience Toolkit (EMET) 4.1 and above can mitigate this Internet Explorer vulnerability and is supported by Windows XP. Besides using EMET, Symantec Security Response encourages users to temporarily switch to a different Web browser until a patch is made available by the vendor.

Symantec protects customers against this attack with the following detections:

We will update this blog with additional information as soon as it becomes available.

Update – April 28, 2014:
In order to mitigate Microsoft Internet Explorer Remote Code Execution Vulnerability (CVE-2014-1776), Symantec provides the following recommendations.

Microsoft states that versions of the Enhanced Mitigation Experience Toolkit (EMET) 4.1 and above can mitigate this vulnerability in Internet Explorer. The toolkit is available for Windows XP users as well. If using EMET is not an option, users can consider mitigating the currently known exploit by unregistering a DLL file named VGX.DLL. This file provides support for VML (Vector Markup Language) in the browser. This is not required by the majority of users. However, by unregistering the library, any application that uses the DLL may no longer function properly. Also, some applications installed on the system may potentially re-register the DLL. With this in mind, the following one line of instruction can be executed to make the system immune from attacks attempting to leverage the currently known exploit for this vulnerability. This line of instruction can be used for all affected operating systems:

"%SystemRoot%\System32\regsvr32.exe" -u "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll"

We have developed a batch file that can be used to perform the task for those who may be required to administrate large IT infrastructures.

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Note: Users will need to rename the file using a .bat extension.

The batch file has the ability to verify the current state of the DLL file and unregister the DLL as needed. The script outlined in the batch file is very simple and can be used as a basis to customize the code to fit the needs of certain system environments.

Please note that recommendations, such as the one provided here, may not be possible for future vulnerabilities. We recommend that unsupported operating systems, such as Windows XP, be replaced with supported versions as soon as possible.

Update – May 02, 2014:
Microsoft has released an out-of-band security update to address this vulnerability. For more information, see the following Microsoft security advisory:

Out-of-Band Release to Address Microsoft Security Advisory 2963983