Re: [Full-disclosure] SSH.com Communications SSH Tectia Authentication Bypass Remote Zeroday Exploit (king cope)

[<Samuel.Lavitt@xxxxxxx>]

High/Critical severity remote authentication bypass in Tectia SSH Server - 
Workaround

SUMMARY
On Sunday December 2, 2012, a remote authentication bypass vulnerability was 
disclosed which affects the current Unix/Linux versions of Tectia SSH Server. 
This does not affect client. Windows and zOS servers are not affected. Servers 
that have "old-style" password authentication already disabled are not 
affected. Password authentication through keyboard-interactive authentication 
is safe.
This vulnerability exploits a bug in the SSH USERAUTH CHANGE REQUEST function. 
This vulnerability has been confirmed by internal testing.
A workaround is to disable "old-style" password authentication on affected 
versions. The bug only affects “old-style” password authentication. 
Keyboard-interactive, GSSAPI, and public key authentication methods are not 
affected.

AFFECTED PRODUCTS AND VERSIONS
SSH Tectia Server 6.0.4 to 6.0.20
SSH Tectia Server 6.1.0 to 6.1.12
SSH Tectia Server 6.2.0 to 6.2.5
SSH Tectia Server 6.3.0 to 6.3.2
All products are only the Unix/Linux versions (not Windows or zOS)

CURRENT SITUATION
Effective workaround exists. Updated versions providing a permanent fix to this 
issue are in testing and are expected to be released within the next 24-48 
hours.

WORKAROUND
An immediate workaround is to disable “old-style” password authentication by 
editing the /etc/ssh2/ssh-server-config.xml configuration file. Comment out the 
line (all of them if multiple) containing <auth-password /> In XML, comment 
syntax is <!-- … -->, i.e., change the line to:
<!-- <auth-password /> -->
WE STRONGLY ADVISE MAKING THIS CHANGE IMMEDIATELY, AT LEAST ON ALL EXTERNAL 
FACING SERVERS.

Note: it is also good to make sure you have keyboard-interactive enabled so 
that you don't completely prevent password authentication, i.e., that the 
following is in the server configuration file:
<auth-keyboard-interactive>
<submethod-password />
</auth-keyboard-interactive>

SSH Communications Security would like to credit "king cope", 
isowarez.isowarez.isowarez@xxxxxxxxxxxxxx, with this discovery, as that was the 
first report we received of this issue.
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