• SSH Keys Generated on Debian/Ubuntu Compromised

    mojombo May 13

    A security warning posted on the Debian security list today warns that SSH keys generated on Debian based systems (including Ubuntu) have a highly predictable random number generator. This corroborates what we’ve been seeing here at GitHub.

    Luciano Bello discovered that the random number generator in Debian’s openssl package is predictable. This is caused by an incorrect Debian-specific change to the openssl package (CVE-2008-0166). As a result, cryptographic key material may be guessable.

    This is a Debian-specific vulnerability which does not affect other operating systems which are not based on Debian. However, other systems can be indirectly affected if weak keys are imported into them.

    It is strongly recommended that all cryptographic key material which has been generated by OpenSSL versions starting with 0.9.8c-1 on Debian systems is recreated from scratch. Furthermore, all DSA keys ever used on affected Debian systems for signing or authentication purposes should be considered compromised; the Digital Signature Algorithm relies on a secret random value used during signature generation.

    We STRONGLY recommend that you discontinue use of any keys generated under this configuration and update your GitHub keys after you’ve patched your Debian based system.

    • Comments

    • jmazzi about 2 hours later

      “This corroborates what we’ve been seeing here at GitHub.” Could you elaborate on that point please? :)

    • elliottcable about 6 hours later

      jmazzi: If I remember correctly, there was an incident or two where two people had the exact same SSH keys in the GitHub database. Chris twittered it at the time, you really should follow him.

    • mojombo about 24 hours later

      jmazzi: we identified several cases where different users (with no knowledge of each other) generated the same public keys. We’ve notified all parties and revoked the keys. All instances of this were caused by keys generated on Ubuntu.

    • dustin 2 days later

      Is it possible for you guys to check the keys against list this guy generated? It seems like you may be able to proactively notify users and project owners if they have a key that is at risk without too much effort.

    • jf 18 days later

      hi folks, when does a key change in my account take place? I’ve regenerated, and uploaded my new public key already, made sure that it is not in the vulnerable list, and yet when pushing, I still get “Permission denied (publickey)”?

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