Micha Riser has reported some weaknesses in EncFS, which can be exploited by malicious people to bypass certain security features.
1) The application uses only 4 bytes as initialisation vector although 8 bytes are intended, which can lead to e.g. lower cryptographic security than expected.
2) The application does not properly protect against "watermarking" attacks when using the CBC mode, which can be exploited to e.g. determine if a specially crafted file has been stored.
3) When using CFB cipher mode, cipher blocks containing a single byte can disclose certain information about the file content to the attacker.
The weaknesses are reported in versions prior to 1.7. Other versions may also be affected.
Solution: Update to version 1.7, which fixes weaknesses #1 and #2 by using a different initialisation vector setup code for new file systems. Use the "MAC block headers" or "MAC random bytes" options to mitigate the CFB cipher mode attacks.
Provided and/or discovered by: Micha Riser
Original Advisory: Micha Riser:
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Subject: EncFS Multiple Weaknesses
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