Updated pam packages that fix two security flaws, resolve two bugs, and add an enhancement are now available for CentOS Linux 4. This update has been rated as having moderate security impact by the Red Hat Security Response Team.
Pluggable Authentication Modules (PAM) provide a system whereby administrators can set up authentication policies without having to recompile programs that handle authentication. A flaw was found in the way pam_console set console device permissions. It was possible for various console devices to retain ownership of the console user after logging out, possibly leaking information to another local user. (CVE-2007-1716) A flaw was found in the way the PAM library wrote account names to the audit subsystem. An attacker could inject strings containing parts of audit messages, which could possibly mislead or confuse audit log parsing tools. (CVE-2007-3102) As well, these updated packages fix the following bugs: * the pam_xauth module, which is used for copying the X11 authentication cookie, did not reset the "XAUTHORITY" variable in certain circumstances, causing unnecessary delays when using su command. * when calculating password similarity, pam_cracklib disregarded changes to the last character in passwords when "difok=x" (where "x" is the number of characters required to change) was configured in "/etc/pam.d/system-auth". This resulted in password changes that should have been successful to fail with the following error: BAD PASSWORD: is too similar to the old one This issue has been resolved in these updated packages. * the pam_limits module, which provides setting up system resources limits for user sessions, reset the nice priority of the user session to "0" if it was not configured otherwise in the "/etc/security/limits.conf" configuration file. These updated packages add the following enhancement: * a new PAM module, pam_tally2, which allows accounts to be locked after a maximum number of failed log in attempts. All users of PAM should upgrade to these updated packages, which resolve these issues and add this enhancement.