SCRAM: Client does not check low iteration counter #811 #813
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Using mechanism SCRAM, a client does not abort authentication when the given iteration counter is lower than 4096. A hostile server can send a small iteration counter (e.g. 1) and forces the client to send a ClientProof that is calculated with lowest computation time. Thus the hostile server can recover the client's password faster with an offline dictionary or brute-force attack. This fix compares the iteration counter with the recommended minimum of 4096 and aborts the authentication if the server violates the recommended minimum. Signed-off-by: Guido Kiener <[email protected]>
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PRs should be targeting master, please adjust. |
Thanks. It's now reopened in #815. |
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Using mechanism SCRAM, a client does not abort authentication when the given iteration counter is lower than 4096.
A hostile server can send a small iteration counter (e.g. 1) and forces the client to send a ClientProof that is calculated with lowest computation time. Thus the hostile server can recover the client's password faster with an offline dictionary or brute-force attack.
This fix compares the iteration counter with the recommended minimum of 4096 and aborts the authentication if the server violates the recommended minimum.