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UNIRAS Brief - 732/06 - FreeBSD Security Advisory: FreeBSD-SA-06:24.libarchive



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______________________________________________________________________________

 UNIRAS (UK Government CERT) Briefing - 732/06 dated 09.11.06 time 14:35
 UNIRAS is part of NISCC (the UK National Infrastructure Security
 Co-ordination Centre)
______________________________________________________________________________

 UNIRAS material is available from the NISCC website at www.niscc.gov.uk
______________________________________________________________________________

Title
=====

FreeBSD Security Advisory: FreeBSD-SA-06:24.libarchive 

Detail
======

If the end of an archive is reached while attempting to "skip" past a
region of an archive, libarchive will enter an infinite loop wherein it
repeatedly attempts (and fails) to read further data.


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=============================================================================
FreeBSD-SA-06:24.libarchive                                 Security Advisory
                                                          The FreeBSD Project

Topic:          Infinite loop in corrupt archives handling in libarchive(3)

Category:       core
Module:         libarchive
Announced:      2006-11-08
Credits:        Rink Springer
Affects:        FreeBSD 6-STABLE after 2006-09-05 05:23:51 UTC
Corrected:      2006-11-08 14:05:40 UTC (RELENG_6, 6.2-RC1)
CVE Name:       CVE-2006-5680

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

The libarchive library provides a flexible interface for reading and
writing streaming archive files such as tar and cpio, and has been the
basis for FreeBSD's implementation of the tar(1) utility since FreeBSD 5.3.

II.  Problem Description

If the end of an archive is reached while attempting to "skip" past a
region of an archive, libarchive will enter an infinite loop wherein it
repeatedly attempts (and fails) to read further data.

III. Impact

An attacker able to cause a system to extract (via "tar -x" or another
application which uses libarchive) or list the contents (via "tar -t" or
another libarchive-using application) of an archive provided by the
attacker can cause libarchive to enter an infinite loop and use all
available CPU time.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE dated after the correction
date.

2) To patch your present system:

The following patches have been verified to apply to affected systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch http://security.FreeBSD.org/patches/SA-06:24/libarchive.patch
# fetch http://security.FreeBSD.org/patches/SA-06:24/libarchive.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libarchive
# make obj && make depend && make && make install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
  Path
- - -------------------------------------------------------------------------
RELENG_6
  src/lib/libarchive/archive_read_support_compression_none.c      1.6.2.2
- - -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-5680

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-06:24.libarchive.asc
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______________________________________________________________________________

UNIRAS wishes to acknowledge the contributions of FreeBSD for the
information contained in this briefing.
______________________________________________________________________________

This notice contains information released by the original author.
Some of the information may have changed since it was released. If the
vulnerability affects you, it may be prudent to retrieve the advisory
from the site of the original source to ensure that you receive the most
current information concerning that problem.

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trade name, trademark manufacturer, or otherwise, does not constitute or
imply its endorsement, recommendation, or favouring by UNIRAS or NISCC.
The views and opinions of authors expressed within this notice shall not
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Neither UNIRAS or NISCC shall also accept responsibility for any errors
or omissions contained within this briefing notice. In particular, they
shall not be liable for any loss or damage whatsoever, arising from or
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UNIRAS is a member of the Forum of Incident Response and Security Teams
(FIRST) and has contacts with other international Incident Response
Teams (IRTs) in order to foster cooperation and coordination in incident
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information sharing amongst its members and the community at large.
______________________________________________________________________________

<End of UNIRAS Briefing>

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