Rar CmdExtract::UnstoreFile Integer Truncation Memory Corruption

2015-12-10 23:05:25

Source: https://code.google.com/p/google-security-research/issues/detail?id=550

The attached file crashes in CmdExtract::UnstoreFile because the signed int64 DestUnpSize is truncated to an unsigned 32bit integer. Perhaps CmdExtract::ExtractCurrentFile should sanity check Arc.FileHead.UnpSize early.

I observed this crash in Avast Antivirus, but the origin of the code appears to be the unrar source distribution. I imagine many other antiviruses will be affected, and presumably WinRAR and other archivers.

Proof of Concept:
https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/38930.zip

Fixes

No fixes

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