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TurboLinux Security Announcement: Package: xlockmore-4.16 and earlier

May 30, 2000, 22:14 (0 Talkback[s])
(Other stories by Katherine M. Moussouris)

Date: Tue, 30 May 2000 14:46:08 -0700 (PDT)
From: Katherine M. Moussouris k8e@turbolinux.com
To: tl-security-announce@turbolinux.com
Subject: [TL-Security-Announce] xlockmore TLSA2000012-1.txt

                        TurboLinux Security Announcement

        Package: xlockmore-4.16 and earlier
        Date: Mon May 29 20:29:06 PDT 2000

        Affected TurboLinux versions: 6.0.4 and earlier; 6.0.5 NOT affected
        Vulnerability Type: local users can view shadowed password file
        TurboLinux Advisory ID#:  TLSA2000012-1

        Credits:  This vulnerability was discovered by COVERT labs at
        Network Associates, Inc., published to BUGTRAQ Mon, 29 May 2000.

A security hole was discovered in the package mentioned above. Please update the package in your installation as soon as possible or disable the service.

1. Problem Summary

From the COVERT labs NAI advisory:

"The xlock program locks an X server until a valid password is entered. The command line option -mode provides a user with a mechanism to change the default display shown when the X server is locked. xlock is installed with privileges to obtain password information, although these are dropped as early as possible. An overflow in the -mode command line option allows a malicious attacker to reveal arbitrary portions of xlock's address space including the shadow password file."

2. Impact

A local user can use the overflow to read the shadowed password file.

3. Solution

Update the package from our ftp server by running the following command:

rpm -Fvh ftp_path_to_filename

Where ftp_path_to_filename is the following:


The source RPM can be downloaded here:


**Note: You must rebuild and install the RPM if you choose to download and install the SRPM. Simply installing the SRPM alone WILL NOT CLOSE THE SECURITY HOLE.

Please verify the MD5 checksum of the update before you install:

  MD5 sum                               Package Name

4987a64d63c0e803e61df11c106d33a3 xlockmore-4.16.1-1.i386.rpm

fc29032bbef8b9d111b9cadd43954ecc xlockmore-4.16.1-1.src.rpm

These packages are GPG signed by Turbolinux for security. Our key is available here:


To verify a package, use the following command:

rpm --checksig name_of_rpm

To examine only the md5sum, use the following command:

rpm --checksig --nogpg name_of_rpm

**Note: Checking GPG keys requires RPM 3.0 or higher.

You can find more updates on our ftp server:

ftp://ftp.turbolinux.com/pub/updates/6.0/security/ for TL6.0 Workstation and Server security updates
ftp://ftp.turbolinux.com/pub/updates/4.0/security/ for TL4.0 Workstation and Server security updates

Our webpage for security announcements:


If you want to report vulnerabilities, please contact:


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