SSH Communications Security Information for VU#161576

"SSH1 has been officially deprecated for some time now. I strongly urge all users to switch to the latest SSH Secure Shell (or generally to the version 2 of the Secure Shell protocol). The version 1.x protocol suffers from many security problems.

"I do, however, have reason to believe that the issue reported here may be a fluke. There was discussion about the Bleisenbacher attack against SSH1 some years ago (after the attack became public), and the general conclusion at that time was that it didn't affect Secure Shell. The session key in SSH1 is encrypted TWICE, once by the server key, and once by the host key. To decrypt the session key, one would need to be able to determine BOTH the server key and the host key. I am not aware of a variant of the Bleisenbacher attack that would do this....

"As a fix, I would add upgrading to the lastest version (ssh-3.1.2, or ssh-1.2.33 if one insists on using the deprecated 1.x protocol)."

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