Microsoft releases fix for Applocker bypass flaw

Windows vault easily opened with macros

Microsoft has released a temporary fix for a flaw in its latest operating systems that allows untrusted users to bypass security measures preventing them from running unauthorized applications.

AppLocker allows administrators to restrict the applications that can be run on computers running Windows 7 and Windows Server 2008. But end users can easily override the restrictions by invoking a variety of automated script features, including macros in Microsoft Office. Programming flags such as SANDBOX_INERT and LOAD_IGNORE_CODE_AUTHZ_LEVEL could even allow malware stashed in temporary folders to be executed.

Microsoft on Wednesday published a hotfix to correct the flaw.

"This hotfix might receive additional testing," Microsoft's advisory stated. "Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix."

The advisory didn't say when that update would be released. ®

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