(RHSA-2007:0555) Moderate: pam security, bug fix, and enhancement update

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:

• truncated MD5-hashed passwords in “/etc/shadow” were treated as valid,
  resulting in insecure and invalid passwords.

• the pam_namespace module did not convert context names to raw format and
  did not unmount polyinstantiated directories in some cases. It also crashed
  when an unknown user name was used in “/etc/security/namespace.conf”, the
  pam_namespace configuration file.

• the pam_selinux module was not relabeling the controlling tty correctly,
  and in some cases it did not send complete information about user role and
  level change to the audit subsystem.

These updated packages add the following enhancements:

• pam_limits module now supports parsing additional config files placed
  into the /etc/security/limits.d/ directory. These files are read after the
  main configuration file.

• the modules pam_limits, pam_access, and pam_time now send a message to
  the audit subsystem when a user is denied access based on the number of
  login sessions, origin of user, and time of login.

• pam_unix module security properties were improved. Functionality in the
  setuid helper binary, unix_chkpwd, which was not required for user
  authentication, was moved to a new non-setuid helper binary, unix_update.

All users of PAM should upgrade to these updated packages, which resolve
these issues and add these enhancements.