__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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__________________________________________________________
INFORMATION BULLETIN
Red Hat Linux Password Locking Race Vulnerability
[RHSA-2002:132-19]
July 30, 2002 19:00 GMT Number M-104
[Revised 14 July 03]
______________________________________________________________________________
PROBLEM: A locally exploitable vulnerability is present in the
util-linux package shipped with Red Hat Linux.
PLATFORM: Red Hat Linux 7.3 and earlier
DAMAGE: Under certain conditions, a carefully crafted attack sequence
can be performed to exploit a complex file locking and
modification race present in this utility allowing changes to
be made to /etc/passwd.
SOLUTION: All users of Red Hat Linux should update to the errata
util-linux packages which contain a patch to correct this
vulnerability.
______________________________________________________________________________
VULNERABILITY The risk is LOW. A carefully crafted attack sequence can be
ASSESSMENT: performed to exploit this vulnerability. In order to
successfully exploit the vulnerability and perform privilege
escalation there is a need for minimal administrator
interaction.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-104.shtml
ORIGINAL BULLETIN: http://rhn.redhat.com/errata/RHSA-2002-132.html
______________________________________________________________________________
Revision History: 07/10/03 - Added packages for Red Hat Linux on IBM iSeries
and pSeries systems.
[***** Start RHSA-2002:132-19 *****]
Updated util-linux package fixes password locking race
Advisory: RHSA-2002:132-19
Last updated on: 2003-07-10
Affected Products: Red Hat Linux 6.2
Red Hat Linux 7.0
Red Hat Linux 7.1
Red Hat Linux 7.1 for iSeries
Red Hat Linux 7.1 for pSeries
Red Hat Linux 7.2
Red Hat Linux 7.3
CVEs (cve.mitre.org): CVE-2002-0638
Security Advisory
Details:
A locally exploitable vulnerability is present in the util-linux package
which shipped with Red Hat Linux.
[Updated 8 July 2003]
Added packages for Red Hat Linux on IBM iSeries and pSeries systems.
The util-linux package contains a large variety of low-level system
utilities that are necessary for a Linux system to function. The chfn
utility included in this package allows users to modify personal
information stored in the system-wide password file, /etc/passwd. In order
to modify this file, this application is installed setuid root.
Under certain conditions, a carefully crafted attack sequence can be
performed to exploit a complex file locking and modification race present
in this utility allowing changes to be made to /etc/passwd.
In order to successfully exploit the vulnerability and perform privilege
escalation there is a need for minimal administrator interaction.
Additionally, the password file must be over 4 kilobytes, and the local
attackers entry must not be in the last 4 kilobytes of the password file.
The Common Vulnerabilities and Exposures project (cve.mitre.org) has
assigned the name CAN-2002-0638 to this issue.
An interim workaround is to remove setuid flags from /usr/bin/chfn and
/usr/bin/chsh. All users of Red Hat Linux should update the packages
contained in this erratum, which are patched to correct this vulnerability.
Many thanks to Michal Zalewski of Bindview for alerting us to this issue.
Updated packages:
Red Hat Linux 6.2
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.10f-7.6.2.src.rpm
[ via FTP ] [ via HTTP ] 0af6265f350849394fc54ca7f006fd82
alpha:
util-linux-2.10f-7.6.2.alpha.rpm
[ via FTP ] [ via HTTP ] 4e30115e7fd311ac8496637c03716473
i386:
util-linux-2.10f-7.6.2.i386.rpm
[ via FTP ] [ via HTTP ] e1c0e740d41aaddc7817604ed449e872
sparc:
util-linux-2.10f-7.6.2.sparc.rpm
[ via FTP ] [ via HTTP ] fe28b4c80b9fe909c38f913b899ddb16
Red Hat Linux 7.0
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.10m-12.7.0.src.rpm
[ via FTP ] [ via HTTP ] 4aa3502469cc8255aea825cebe82d4db
alpha:
util-linux-2.10m-12.7.0.alpha.rpm
[ via FTP ] [ via HTTP ] b2e1b30a837e440297acba35d13fab77
i386:
util-linux-2.10m-12.7.0.i386.rpm
[ via FTP ] [ via HTTP ] af9aca214e81e4f306d49ed398a79f22
Red Hat Linux 7.1
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.11f-17.7.2.src.rpm
[ via FTP ] [ via HTTP ] dc87f0566da2f6a37443f9614cb1ff61
alpha:
util-linux-2.11f-17.7.2.alpha.rpm
[ via FTP ] [ via HTTP ] c3bc4100fdc6e4e7c4b524c16991f168
i386:
util-linux-2.11f-17.7.2.i386.rpm
[ via FTP ] [ via HTTP ] 668e4b28b07dcd9718744b2c59383bc2
ia64:
util-linux-2.11f-17.7.2.ia64.rpm
[ via FTP ] [ via HTTP ] 200e1661f445fca662f51d810f650448
Red Hat Linux 7.1 for iSeries
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.11f-17.7.2.src.rpm
[ via FTP ] [ via HTTP ] dc87f0566da2f6a37443f9614cb1ff61
ppc:
util-linux-2.11f-17.7.2.ppc.rpm
[ via FTP ] [ via HTTP ] 39b2f33573da14946639e38f7dbccaec
Red Hat Linux 7.1 for pSeries
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.11f-17.7.2.src.rpm
[ via FTP ] [ via HTTP ] dc87f0566da2f6a37443f9614cb1ff61
ppc:
util-linux-2.11f-17.7.2.ppc.rpm
[ via FTP ] [ via HTTP ] 39b2f33573da14946639e38f7dbccaec
Red Hat Linux 7.2
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.11f-17.7.2.src.rpm
[ via FTP ] [ via HTTP ] dc87f0566da2f6a37443f9614cb1ff61
i386:
util-linux-2.11f-17.7.2.i386.rpm
[ via FTP ] [ via HTTP ] 668e4b28b07dcd9718744b2c59383bc2
ia64:
util-linux-2.11f-17.7.2.ia64.rpm
[ via FTP ] [ via HTTP ] 200e1661f445fca662f51d810f650448
Red Hat Linux 7.3
--------------------------------------------------------------------------------
SRPMS:
util-linux-2.11n-12.7.3.src.rpm
[ via FTP ] [ via HTTP ] 474988909a18c0f73a65de40bf946e92
i386:
losetup-2.11n-12.7.3.i386.rpm
[ via FTP ] [ via HTTP ] b1b6d7852f75d1014204b7853f656427
mount-2.11n-12.7.3.i386.rpm
[ via FTP ] [ via HTTP ] 496ec0a9c0720ba5bed7baa917114aac
util-linux-2.11n-12.7.3.i386.rpm
[ via FTP ] [ via HTTP ] da8c81ee48c180694b89c9c99f543256
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 Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:
up2date
This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.
References:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2002-0638
http://www.kb.cert.org/vuls/id/405955
http://razor.bindview.com/publish/advisories/adv_chfn.html
Keywords:
locking, password, race, util-linux
--------------------------------------------------------------------------------
The listed packages are GPG signed by Red Hat, Inc. for security. Our key is
available at: http://www.redhat.com/solutions/security/news/publickey/#key
You can verify each package and see who signed it with the following command:
rpm --checksig -v 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:
md5sum filename
The Red Hat security contact is security@redhat.com. More contact details at
http://www.redhat.com/solutions/security/news/contact.html
[***** End RHSA-2002:132-19 *****]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of Red Hat for the
information contained in this bulletin.
_______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
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among computer security teams worldwide.
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E-mail: ciac@ciac.org
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communities receive CIAC bulletins. If you are not part of these
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This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
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employees, makes any warranty, express or implied, or assumes any
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