AOSA-2017-0034: OPENSSH IN TARBALLS SHIPPED IDENTICAL HOST KEYS

APRIL 18, 2017

Most good programmers do programming not because they expect to get paid or get adulation by the public, but because it is fun to program. – Linus Torvalds

This is an issue of great emergency, please update your system with the newest openssh package to workaround this security vulnerability!

In our traditional way of generating AOSC OS release tarballs, SSH Daemon host keys were generated only once across any AOSC OS install because the tarballs were built from a single stub tarball, then to a Base variant - which already contains a copy of OpenSSH (with keys generated) - then all other variants were generated from the Base tarball with extra sets of packages. The result was - due to our ignorance - that all SSH Daemon host keys are generated only once, a great security threat to all AOSC OS users with their SSH Daemon or sshd.service enabled.

To workaround this for all existing users, (once again) please update your system with the latest openssh package, if you see the following message when installing the update…

Regenerating SSH Keys for AOSA-2017-0034...
removed '/etc/ssh/ssh_host_dsa_key'
removed '/etc/ssh/ssh_host_dsa_key.pub'
removed '/etc/ssh/ssh_host_ecdsa_key'
removed '/etc/ssh/ssh_host_ecdsa_key.pub'
removed '/etc/ssh/ssh_host_ed25519_key'
removed '/etc/ssh/ssh_host_ed25519_key.pub'
removed '/etc/ssh/ssh_host_rsa_key'
ssh-keygen: generating new host keys: RSA DSA ECDSA ED25519

Then your SSH Daemon host keys are regenerated, and they are expected to be unique across any device. You would not need to restart your sshd.service, but when clients connect to your device, they may receive a warning…

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
<ECSDA key here>
Please contact your system administrator.

Please remove the line (or inform users of your AOSC OS host with SSH enabled to do so) from your ~/.ssh/known_host file containing the key described above - another method is to identify the host you are attempting to connect to, and remove the line containing the host.

Updates to openssh are now available for amd64, arm64, armel, mipsel, powerpc, and ppc64.

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