Multiple 7-Zip Vulnerabilities Discovered

Re:Multiple 7-Zip Vulnerabilities Discovered by paulfr on Thursday May 12, 2016 @03:03PM (#11685892)

I just did some testing and it's even worse than that: 7-zip completely ignores the file extension and snoops the file format based on the file contents only.

So simply opening a malicious ".zip" file on Windows could trigger the HFS+ vulnerability. Using 7-zip to open any file means you have a HUGE attack surface.

EDIT: One simple way to mitigate this issue would be to just throw a confirmation prompt if the file extension matches a known format but 7-zip is about to run a decoder for a different format.

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Re:Multiple 7-Zip Vulnerabilities Discovered by colejohnson66 on Thursday May 12, 2016 @03:35PM (#11686101)

IIRC, 7-zip does tell you if the actual format is different. At least it does when I extract some DMGs; it tells me it's actually an HFS "file".

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Re:Multiple 7-Zip Vulnerabilities Discovered by paulfr on Thursday May 12, 2016 @04:21PM (#11686458)

Not on Windows, at least. The properties dialog can tell you it uses HFS+ if you ask for it, but it's too late because the HFS+ code has already been executed.

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Re:Multiple 7-Zip Vulnerabilities Discovered by colejohnson66 on Thursday May 12, 2016 @06:13PM (#11687224)

I meant when right clicking the archive am choosing "Extract to..." or something using Explorer's context menu.

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Re:Multiple 7-Zip Vulnerabilities Discovered by paulfr on Thursday May 12, 2016 @06:33PM (#11687341)

Interesting, it does display a warning in this case! But it doesn't interrupt extraction so if it's a malicious file the code will still execute.

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