Vigil@nce: RHEL 4, access to a locked account via su
July 2008 by Vigil@nce
SYNTHESIS
A wrong syntax in the /etc/pam.d/su configuration file allows an
access to locked or expired accounts.
Gravity: 1/4
Consequences: user access/rights
Provenance: user shell
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: high (3/3)
Creation date: 25/07/2008
Identifier: VIGILANCE-VUL-7970
IMPACTED PRODUCTS
– Red Hat Enterprise Linux [confidential versions]
DESCRIPTION
PAM is a service which allows an authentication configuration. It
is notably used for commands such as su, login, passwd, etc.
The /etc/pam.d/su file contains a "pam_succeed_if.so" module which
allows access to locked accounts if the uid of the user equals to
0.
However, the /etc/pam.d/su RHEL 4 configuration file contains:
[...] pam_succeed_if.so uid=0 [...]
Instead of:
[...] pam_succeed_if.so uid = 0 [...]
The uid option and its parameter 0, are interpreted like a unique
option "uid=0". As this option is not recognized, it does not
restrict the usage of the su command to the user with the uid=0.
A local attacker knowing a password of a locked account will be
able to access it.
CHARACTERISTICS
Identifiers: 446488, BID-30363, CVE-2008-1946, RHSA-2008:0780-01,
VIGILANCE-VUL-7970