(Mandrake Issues Fix) GNOME Display Manager (gdm) Lets Local Users View Files With Root Privileges
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SecurityTracker Alert ID: 1007552
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CVE Reference: CAN-2003-0547
(Links to External Site)
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Updated: Dec 1 2003
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Original Entry Date: Aug 22 2003
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Impact: Denial of service via network, Disclosure of system information, Disclosure of user information
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Fix Available: Yes
Vendor Confirmed: Yes
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Version(s): prior to 2.4.1.6
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Description: Several vulnerabilities were reported in the GNOME Display Manager (gdm). A local user can view arbitrary files on the system. A remote user may be able to cause the gdm daemon may crash.
It is reported that a local user can make a symbolic link (symlink) from an arbitrary file on the system to the '~/.xsession-errors'
file. Then, when gdm runs and is configured with the "examine session errors" option, the local user can view the symlinked file
(CVE: CAN-2003-0547). Any file can be read with root privileges, according to the report.
It is also reported that there are
two vulnerabilties in the X Display Manager Control Protocol (XDMCP) implementation. A remote user can cause the gdm daemon to
crash. If a host expires, the gdm daemon may crash (CVE: CAN-2003-0548). If an authorization key name is shorter then 18 bytes,
the gdm daemon may crash (CVE: CAN-2003-0549).
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Impact: A local user can view arbitrary files with root privileges.
A remote user may be able to cause the daemon to crash.
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Solution: Mandrake has released a fix.
Corporate Server 2.1:
47a2d84bfff0e842657e789e085b434d corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
8536d89374219e42ad6ca6c441ffb0d1 corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
35ab7f8231548f1daa4571bfb5e77054 corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Corporate Server 2.1/x86_64:
252fc231c85e88411ca50a05f0404688 x86_64/corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.x86_64.rpm
3f8b47c14e0d7fc4c2d76171e3ee0b5a
x86_64/corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.x86_64.rpm
35ab7f8231548f1daa4571bfb5e77054 x86_64/corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Mandrake Linux 9.0:
47a2d84bfff0e842657e789e085b434d 9.0/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
8536d89374219e42ad6ca6c441ffb0d1
9.0/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
35ab7f8231548f1daa4571bfb5e77054 9.0/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Mandrake
Linux 9.1:
9d8a97cc5f475f16eeb73caa9d7d8e6b 9.1/RPMS/gdm-2.4.1.6-0.3mdk.i586.rpm
4f866c5b5b4903d1b0751bcb6dc28d0f 9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.i586.rpm
91f0ff2421135e32f604d6cb82081439 9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm
Mandrake Linux 9.1/PPC:
0cb8fbd74766c4d0036cab36d57b6081
ppc/9.1/RPMS/gdm-2.4.1.6-0.3mdk.ppc.rpm
fb0df358c4d6c9a7cf3982c4d3258004 ppc/9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.ppc.rpm
91f0ff2421135e32f604d6cb82081439
ppc/9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm
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Vendor URL: www.5z.com/jirka/gdm.html (Links to External Site)
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Cause: Access control error, Exception handling error
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Underlying OS: Linux (Mandrake)
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Underlying OS Comments: 9.0, 9.1, Corporate Server 2.1
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Reported By: Mandrake Linux Security Team <security@linux-mandrake.com>
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Message History:
This archive entry is a follow-up to the message listed below.
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Source Message Contents
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Date: 22 Aug 2003 00:10:27 -0000
From: Mandrake Linux Security Team <security@linux-mandrake.com>
Subject: MDKSA-2003:085 - Updated gdm packages fix vulnerabilities
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
________________________________________________________________________
Mandrake Linux Security Update Advisory
________________________________________________________________________
Package name: gdm
Advisory ID: MDKSA-2003:085
Date: August 21st, 2003
Affected versions: 9.0, 9.1, Corporate Server 2.1
________________________________________________________________________
Problem Description:
Several vulnerabilities were discovered in versions of gdm prior to
2.4.1.6. The first vulnerability is that any user can read any text
file on the system due to code originally written to be run as the user
logging in was in fact being run as the root user. This code is what
allows the examination of the ~/.xsession-errors file. If a user makes
a symlink from this file to any other file on the system during the
session and ensures that the session lasts less than ten seconds, the
user can read the file provided it was readable as a text file.
Another two vulnerabilities were found in the XDMCP code that could be
exploited to crash the main gdm daemon which would inhibit starting
any new sessions (although the current session would be unaffected).
The first problem here is due to the indirect query structure being
used right after being freed due to a missing 'continue' statement in a
loop; this happens if a choice of server expired and the client tried
to connect.
The second XDMCP problem is that when authorization data is being
checked as a string, the length is not checked first. If the data is
less than 18 bytes long, the daemon may wander off the end of the
string a few bytes in the strncmp which could cause a SEGV.
These updated packages bring gdm to version 2.4.1.6 which is not
vulnerable to any of these problems. Also note that XDMCP support is
disabled by default in gdm.
________________________________________________________________________
References:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0547
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0548
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0549
________________________________________________________________________
Updated Packages:
Corporate Server 2.1:
47a2d84bfff0e842657e789e085b434d corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
8536d89374219e42ad6ca6c441ffb0d1 corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
35ab7f8231548f1daa4571bfb5e77054 corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Corporate Server 2.1/x86_64:
252fc231c85e88411ca50a05f0404688 x86_64/corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.x86_64.rpm
3f8b47c14e0d7fc4c2d76171e3ee0b5a x86_64/corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.x86_64.rpm
35ab7f8231548f1daa4571bfb5e77054 x86_64/corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Mandrake Linux 9.0:
47a2d84bfff0e842657e789e085b434d 9.0/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
8536d89374219e42ad6ca6c441ffb0d1 9.0/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
35ab7f8231548f1daa4571bfb5e77054 9.0/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm
Mandrake Linux 9.1:
9d8a97cc5f475f16eeb73caa9d7d8e6b 9.1/RPMS/gdm-2.4.1.6-0.3mdk.i586.rpm
4f866c5b5b4903d1b0751bcb6dc28d0f 9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.i586.rpm
91f0ff2421135e32f604d6cb82081439 9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm
Mandrake Linux 9.1/PPC:
0cb8fbd74766c4d0036cab36d57b6081 ppc/9.1/RPMS/gdm-2.4.1.6-0.3mdk.ppc.rpm
fb0df358c4d6c9a7cf3982c4d3258004 ppc/9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.ppc.rpm
91f0ff2421135e32f604d6cb82081439 ppc/9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm
________________________________________________________________________
Bug IDs fixed (see https://qa.mandrakesoft.com for more information):
________________________________________________________________________
To upgrade automatically, use MandrakeUpdate or urpmi. The verification
of md5 checksums and GPG signatures is performed automatically for you.
A list of FTP mirrors can be obtained from:
http://www.mandrakesecure.net/en/ftp.php
All packages are signed by MandrakeSoft for security. You can obtain
the GPG public key of the Mandrake Linux Security Team by executing:
gpg --recv-keys --keyserver www.mandrakesecure.net 0x22458A98
Please be aware that sometimes it takes the mirrors a few hours to
update.
You can view other update advisories for Mandrake Linux at:
http://www.mandrakesecure.net/en/advisories/
MandrakeSoft has several security-related mailing list services that
anyone can subscribe to. Information on these lists can be obtained by
visiting:
http://www.mandrakesecure.net/en/mlist.php
If you want to report vulnerabilities, please contact
security_linux-mandrake.com
Type Bits/KeyID Date User ID
pub 1024D/22458A98 2000-07-10 Linux Mandrake Security Team
<security linux-mandrake.com>
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