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TUCoPS :: Networks :: n-019.txt

Samba Encrypted Password Buffer Overrun Vulnerability (CIAC N-019)




             __________________________________________________________

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

                             INFORMATION BULLETIN

             Samba Encrypted Password Buffer Overrun Vulnerability
                  [Red Hat Security Advisory RHSA-2002:266-05]

November 26, 2002 00:00 GMT                                       Number N-019
______________________________________________________________________________
PROBLEM:       There is a flaw in the length checking for encrypted password 
               change requests from clients. This vulnerability could be used 
               as a buffer overrun attack on smbd's stack. 
PLATFORM:      Red Hat Linux 7.3 - i386 Red Hat Linux 8.0 - i386 
DAMAGE:        A potential attacker could gain root access on the target 
               machine. 
SOLUTION:      Apply updated packages as described by Red Hat's security 
               advisory. 
______________________________________________________________________________
VULNERABILITY  The risk is MEDIUM. The attack would have to be crafted such 
ASSESSMENT:    that converting a DOS codepage string to little endian UCS2 
               unicode would translate into an executable block of code. 
______________________________________________________________________________
LINKS: 
 CIAC BULLETIN:      http://www.ciac.org/ciac/bulletins/n-019.shtml 
 ORIGINAL BULLETIN:  https://rhn.redhat.com/errata/RHSA-2002-266.html 
______________________________________________________________________________

[***** Start Red Hat Security Advisory RHSA-2002:266-05 *****]

New samba packages available to fix potential security vulnerability

Advisory: RHSA-2002:266-05 
Last updated on: 2002-11-21 
Affected Products: Red Hat Linux 7.3
Red Hat Linux 8.0 

Security Advisory 

Details:

New samba packages are available that fix a security vulnerability present
in samba versions 2.2.2 through 2.2.6. A potential attacker could gain
root access on the target machine. It is strongly encouraged that all Samba
users update to the fixed packages.

As of this time, there are no known exploits for this vulnerability.

There was a bug in the length checking for encrypted password change
requests from clients. A client could potentially send an encrypted
password, which, when decrypted with the old hashed password, could be
used as a buffer overrun attack on smbd's stack. The attack would
have to be crafted such that converting a DOS codepage string to little
endian UCS2 unicode would translate into an executable block of code.

Thanks to the Debian Samba maintainers for discovering this issue, and to
the Samba team for providing the fix (and the problem description text above.)

Updated packages:

Red Hat Linux 7.3 

--------------------------------------------------------------------------------
 
SRPMS: 
samba-2.2.7-1.7.3.src.rpm     		5c8ba729bb3e6d2f0614fd543053e6e9 
  
i386: 
samba-2.2.7-1.7.3.i386.rpm     		92178f0aa6c7ec0cb2b55c0f32c59ca4 
samba-client-2.2.7-1.7.3.i386.rpm     	6915d467d9572737dfbfcac916734084 
samba-common-2.2.7-1.7.3.i386.rpm     	56ce43d49614bf5a79b90dfbd4a77235 
samba-swat-2.2.7-1.7.3.i386.rpm     	82cbcb8e2c3be661e0e6c1c7f9856ecd 
  
Red Hat Linux 8.0 

--------------------------------------------------------------------------------
 
SRPMS: 
samba-2.2.7-2.src.rpm     		9b5ded05dc9cc2c49c40b686ec78caf7 
  
i386: 
samba-2.2.7-2.i386.rpm     		4e2339d23bad01690938748d84dac186 
samba-client-2.2.7-2.i386.rpm     	a7a48f9d6d8e45966172ae1b941e0208 
samba-common-2.2.7-2.i386.rpm     	3bd309562e0cdefc8d4cd5b02ee0b71c 
samba-swat-2.2.7-2.i386.rpm     	0efdfc0d8de8294c0dd4978a82d15991 
 
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.

Keywords:

change, encrypted, password, samba, security 

--------------------------------------------------------------------------------
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.html#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: 
rpm --checksig --nogpg -v filename

Note that you need RPM >= 3.0 to check GnuPG keys. 

[***** End Red Hat Security Advisory RHSA-2002:266-05 *****]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of Red Hat, Inc. 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
University of California. The views and opinions of authors expressed
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Government or the University of California, and shall not be used for
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