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UNIRAS Brief - 282/04 - Jailed processes can manipulate host routing tables


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   UNIRAS (UK Govt CERT) Briefing Notice - 282/04 dated 11.06.04  Time: 12:10  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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Jailed processes can manipulate host routing tables


A programming error resulting in a failure to verify that an attempt to manipulate 
routing tables originated from a non-jailed process.

Hash: SHA1

FreeBSD-SA-04:12.jailroute                                  Security Advisory
                                                          The FreeBSD Project

Topic:          Jailed processes can manipulate host routing tables

Category:       core
Module:         kernel
Announced:      2004-06-07
Credits:        Pawel Malachowski
Affects:        All FreeBSD 4.x releases prior to 4.10-RELEASE
Corrected:      2004-04-06 20:11:53 UTC (RELENG_4)
                2004-06-07 17:44:44 UTC (RELENG_4_9, 4.9-RELEASE-p10)
                2004-06-07 17:42:42 UTC (RELENG_4_8, 4.8-RELEASE-p23)
CVE Name:       CAN-2004-0125
FreeBSD only:   YES

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

I.   Background

The jail(2) system call allows a system administrator to lock up a process and all 
its descendants inside a closed environment with very limited ability to affect the 
system outside that environment, even for processes with superuser privileges.  It 
is an extension of, but far more stringent than, the traditional Unix chroot(2) system call.

The FreeBSD kernel maintains internal routing tables for the purpose of determining 
which interface should be used to transmit packets. These routing tables can be 
manipulated by user processes running with superuser privileges by sending messages 
over a routing socket.

II.  Problem Description

A programming error resulting in a failure to verify that an attempt to manipulate 
routing tables originated from a non-jailed process.

III. Impact

Jailed processes running with superuser privileges could modify host routing tables.  
This could result in a variety of consequences including packets being sent via an 
incorrect network interface and packets being discarded entirely.

IV.  Workaround

No workaround is available.

V.   Solution

Do one of the following:

1) Upgrade your vulnerable system to 4.10-RELEASE, or to the RELENG_4_8 or RELENG_4_9 security 
branch dated after the correction date.


2) Patch your present system:

The following patch has been verified to apply to the FreeBSD 4.8 and 4.9 systems.

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

# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:12/jailroute.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:12/jailroute.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in <URL:http://www.freebsd.org/handbook/kernelconfig.html> 
and reboot the system.

VI.  Correction details

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

Branch                                                           Revision
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Version: GnuPG v1.2.4 (FreeBSD)


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For additional information or assistance, please contact the HELP Desk by 
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UNIRAS wishes to acknowledge the contributions of FreeBSD for the information 
contained in this Briefing. 
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This Briefing contains the 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 canonical site 
to ensure that you receive the most current information concerning that problem.

Reference to any specific commercial product, process, or service by 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 be used for 
advertising or product endorsement purposes.

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 in connection 
with the usage of information contained within this notice.

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 prevention, to prompt 
rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
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<End of UNIRAS Briefing>

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