5564494 2000-10-08 23:09 /115 rader/ Brevbäraren (som är implementerad i) Python
Mottagare: Bugtraq (import) <13163>
Ärende: [RHSA-2000:080-01] tmpwatch has a local denial of service and
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root exploit
From: bugzilla@REDHAT.COM
To: BUGTRAQ@SECURITYFOCUS.COM
Message-ID: <200010062201.e96M1hE13458@porkchop.redhat.com>
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Red Hat, Inc. Security Advisory
Synopsis: tmpwatch has a local denial of service and root exploit
Advisory ID: RHSA-2000:080-01
Issue date: 2000-10-06
Updated on: 2000-10-06
Product: Red Hat Linux
Keywords: tmpwatch, fuser, DoS, fork
Cross references: N/A
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1. Topic:
tmpwatch as shipped in Red Hat Linux 6.1, 6.2, and 7.0 uses fork() to
recursively process subdirectories, enabling a local user to perform
a denial of service attack. Tmpwatch from Red Hat Linux 6.2 and 7.0
also contains an option to allow it to use the fuser command to check
for open files before removal. It executed fuser in an insecure
fashion, allowing a local root exploit.
2. Relevant releases/architectures:
Red Hat Linux 6.1 - i386, alpha, sparc
Red Hat Linux 6.2 - i386, alpha, sparc
Red Hat Linux 7.0 - i386
3. Problem description:
The tmpwatch program periodically cleans up files in temporary
directories by removing all files older than a certain age. In Red
Hat Linux 6.1, 6.2, and 7.0, it used fork() to recursively process
subdirectories. If a malicious user created many layers of
subdirectories (thousands) in a temporary directory monitored by
tmpwatch, the system process table would fill up, requiring a reboot.
Additionally, tmpwatch in 6.2 and 7.0 contains an option, "--fuser",
that attempts to user the fuser command to check if a file is in use
before removal. However, it executed fuser with the system() call in
an insecure fashion. A malicious user could construct an environment
such that this provided them a local root shell. Tmpwatch now uses
execle() to run fuser.
4. Solution:
For each RPM for your particular architecture, run:
rpm -Fvh [filename]
where filename is the name of the RPM.
5. Bug IDs fixed (http://bugzilla.redhat.com/bugzilla for more info):
17286 - tmpwatch run from cron allows locale DoS.
6. RPMs required:
Red Hat Linux 6.2:
alpha:
ftp://updates.redhat.com/6.2/alpha/tmpwatch-2.6.2-1.6.2.alpha.rpm
sparc:
ftp://updates.redhat.com/6.2/sparc/tmpwatch-2.6.2-1.6.2.sparc.rpm
i386:
ftp://updates.redhat.com/6.2/i386/tmpwatch-2.6.2-1.6.2.i386.rpm
sources:
ftp://updates.redhat.com/6.2/SRPMS/tmpwatch-2.6.2-1.6.2.src.rpm
Red Hat Linux 7.0:
i386:
ftp://updates.redhat.com/7.0/i386/tmpwatch-2.6.2-1.7.i386.rpm
sources:
ftp://updates.redhat.com/7.0/SRPMS/tmpwatch-2.6.2-1.7.src.rpm
7. Verification:
MD5 sum Package Name
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b8a670944cc54fd39c9eefb79f147ec1 6.2/SRPMS/tmpwatch-2.6.2-1.6.2.src.rpm
39fe4fbf666e5f9a40503134c05046d8 6.2/alpha/tmpwatch-2.6.2-1.6.2.alpha.rpm
84609abc355fde23ce878e4d310766f8 6.2/i386/tmpwatch-2.6.2-1.6.2.i386.rpm
f4625e9bc27af011a614eaa146586917 6.2/sparc/tmpwatch-2.6.2-1.6.2.sparc.rpm
b1a9201c44a5f921209c9b648ba85ada 7.0/SRPMS/tmpwatch-2.6.2-1.7.src.rpm
8acf394469c47a98fcc589dd0d73b98c 7.0/i386/tmpwatch-2.6.2-1.7.i386.rpm
These packages are GPG signed by Red Hat, Inc. for security. Our key
is available at:
http://www.redhat.com/corp/contact.html
You can verify each package with the following command:
rpm --checksig <filename>
If you only wish to verify that each package has not been corrupted or
tampered with, examine only the md5sum with the following command:
rpm --checksig --nogpg <filename>
8. References:
Thanks go to Internet Security System's X-Force team (xforce@iss.net)
for discovering and documenting the local root exploit.
Copyright(c) 2000 Red Hat, Inc.
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