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TUCoPS :: Linux :: Red Hat/Fedora :: m-104.txt

Red Hat Linux Password Locking Race Vulnerability (CIAC M-104)




            __________________________________________________________

                       The U.S. Department of Energy
                   Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             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
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
    Voice:    +1 925-422-8193 (7x24)
    FAX:      +1 925-423-8002
    STU-III:  +1 925-423-2604
    E-mail:   ciac@ciac.org

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

   World Wide Web:      http://www.ciac.org/
   Anonymous FTP:       ftp.ciac.org

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.

This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
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otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
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Government or the University of California, and shall not be used for
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