FLSA-2005:152771: Updated pam packages fix security issue
Posted on: 05/19/2005 07:01 AM

Updated pam packages are available for Red Hat Linux 7.3 and 9

Fedora Legacy Update Advisory

Synopsis: Updated pam packages fix security issue
Advisory ID: FLSA:152771
Issue date: 2005-05-18
Product: Red Hat Linux
Keywords: Bugfix
CVE Names: CAN-2003-0388

1. Topic:

Updated pam packages that fix a security vulnerability are now available.

PAM (Pluggable Authentication Modules) is a system security tool that allows system administrators to set an authentication policy without having to recompile programs that handle authentication.

2. Relevant releases/architectures:

Red Hat Linux 7.3 - i386
Red Hat Linux 9 - i386

3. Problem description:

These updates fix a potential security problem present in the pam_wheel module. These updates correct a bug in the pam_lastlog module which prevented it from properly manipulating the /var/log/lastlog entry for users with very high user IDs.

The pam_wheel module is used to restrict access to a particular service based on group membership. If the pam_wheel module was used with the "trust" option enabled, but without the "use_uid" option, any local user would be able to spoof the username returned by getlogin(). The user could therefore gain access to a superuser account without supplying a password. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2003-0388 to this issue.

When manipulating the entry in /var/log/lastlog, which corresponds to a given user, the pam_lastlog module calculates the location of the entry by multiplying the UID and the length of an entry in the file. On some systems, the result of this calculation would mistakenly be truncated to 32 bits for users with sufficiently high UIDs.

All users of pam should upgrade to these updated packages, which resolve these issues.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those RPMs which are currently installed will be updated. Those RPMs which are not installed but included in the list will not be updated. Note that you can also use wildcards (*.rpm) if your current directory *only* contains the desired RPMs.

Please note that this update is also available via yum and apt. Many people find this an easier way to apply updates. To use yum issue:

yum update

or to use apt:

apt-get update; apt-get upgrade

This will start an interactive process that will result in the appropriate RPMs being upgraded on your system. This assumes that you have yum or apt-get configured for obtaining Fedora Legacy content. Please visit http://www.fedoralegacy.org/docs for directions on how to configure yum and apt-get.

5. Bug IDs fixed:


6. RPMs required:

Red Hat Linux 7.3:


Red Hat Linux 9:



7. Verification:

SHA1 sum Package Name


These packages are GPG signed by Fedora Legacy for security. Our key is available from http://www.fedoralegacy.org/about/security.php

You can verify each package with the following command:

rpm --checksig -v lt;filenamegt;

If you only wish to verify that each package has not been corrupted or tampered with, examine only the sha1sum with the following command:

sha1sum lt;filenamegt;

8. References:


9. Contact:

The Fedora Legacy security contact is lt;secnotice@fedoralegacy.orggt;. More project details at http://www.fedoralegacy.org

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