of some code, I came across a funny vulnerability inside
OpenPAM (note that this is different from Linux-PAM)
as used in FreeBSD
a FreeBSD 8.1 machine. The bug is that a program,
namely kcheckpass, which is suid to root, is calling
pam_start() with a user provided argument which makes
the PAM stack parse user owned
config files which ends in loading of user
provided DSO's. WTF?!
Interestingly, OpenPAM recently introduced a filter for
the service name via
commit but I dont think that any BSD or so vendor is
aware of it.
A really trivial PoC exploit can be found here.
[Update:] Solaris is not using OpenPAM (at least the OpenSolaris
version I checked), but I could not find code that strips
off certain character sequences. As the PAM setup is different
from the /etc/pam.d we know it is possible that there are no
consequences if the service argument is not filtered.
However a lot of BSD derivates
use OpenPAM and OSX as well. The question is whether one can
find a vector different than the kcheckpass which is usually
found with all KDE3 and KDE4 installs.
If you can confirm vulnerability on any Solaris or non-FreeBSD
machine, please let me know. Also if you found out how OSX
can be exploited this way.