OpenSSH xauth command injection

by admin

Thursday, March 10th, 2016 at 3:00 pm

CVE-2016-3115
Affected configurations: All versions of OpenSSH prior to 7.2p2 with X11Forwarding enabled.

Vulnerability: Missing sanitisation of untrusted input allows an authenticated user who is able to request X11 forwarding to inject commands to xauth(1).
Injection of xauth commands grants the ability to read arbitrary files under the authenticated user’s privilege, Other xauth commands allow limited information leakage, file overwrite, port probing and generally expose xauth(1), which was not written with a hostile user in mind, as an attack surface.

Mitigation / Workaround:
disable x11-forwarding: sshd_config set X11Forwarding no
disable x11-forwarding for specific user with forced-commands: no-x11-forwarding in authorized_keys

::More Info::


CVE-2016-3116
This also affects DropBear, from their Changelog:
“Validate X11 forwarding input. Could allow bypass of authorized_keys command= restrictions”

Mitigation / Workaround:
disable x11-forwarding: re-compile without x11 support: remove #define ENABLE_X11FWD in options.h

::More Info::

Your IP: 172.68.65.95
Hostname: 172.68.65.95

We love our country, but fear our government.