[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

UNIRAS Brief - 548/04 - FreeBSD-SA-04:15.syscons - Boundary checking errors in syscons


- ----------------------------------------------------------------------------------
   UNIRAS (UK Govt CERT) Briefing Notice - 548/04 dated 05.10.04  Time: 14:55  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
- ---------------------------------------------------------------------------------- 
  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
- ----------------------------------------------------------------------------------


FreeBSD Security Advisory - FreeBSD-SA-04:15.syscons - Boundary checking errors in syscons


The syscons CONS_SCRSHOT ioctl(2) does insufficient validation of its input arguments.  
In particular, negative coordinates or large coordinates may cause unexpected behavior.

                 ESB-2004.0625 -- FreeBSD-SA-04:15.syscons
                    Boundary checking errors in syscons
                              5 October 2004

Product:                syscons (FreeBSD 5.x only)
Publisher:              FreeBSD
Operating System:       FreeBSD
Impact:                 Access Privileged Data
                        Increased Privileges
Access:                 Console/Physical
CVE Names:              CAN-2004-0919
Original Bulletin URL:  ftp://ftp.freebsd.org/pub/FreeBSD/CERT/Advisories/FreeBSD-SA-04:15.syscons.asc

- - --------------------------BEGIN INCLUDED TEXT--------------------

Hash: SHA1

FreeBSD-SA-04:15.syscons                                    Security Advisory
                                                          The FreeBSD Project

Topic:          Boundary checking errors in syscons

Category:       core
Module:         sys_dev_syscons
Announced:      2004-10-04
Credits:        Christer Oberg
Affects:        FreeBSD 5.x releases
Corrected:      2004-09-30 17:49:15 UTC (RELENG_5, 5.3-BETA6)
                2004-10-04 17:04:25 UTC (RELENG_5_2, 5.2.1-RELEASE-p11)
CVE Name:       CAN-2004-0919
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

syscons(4) is the default console driver for FreeBSD.  Using the physical keyboard and screen, it provides 
multiple virtual terminals which appear as if they were separate terminals.  One virtual terminal is 
considered current and exclusively occupies the screen and the keyboard; the other virtual terminals are
placed in the background.

II.  Problem Description

The syscons CONS_SCRSHOT ioctl(2) does insufficient validation of its input arguments.  In particular, 
negative coordinates or large coordinates may cause unexpected behavior.

III. Impact

It may be possible to cause the CONS_SCRSHOT ioctl to return portions of kernel memory.  Such memory
might contain sensitive information, such as portions of the file cache or terminal buffers.  This 
information might be directly useful, or it might be leveraged to obtain elevated privileges in some 
way.  For example, a terminal buffer might include a user-entered password.

IV.  Workaround

There is no known workaround.  However, this bug is only exploitable by users who have access to the
physical console or can otherwise open a /dev/ttyv* device node.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to the RELENG_5_2 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 5.2 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-04:15/syscons.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:15/syscons.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
- - - -------------------------------------------------------------------------
  src/sys/dev/syscons/syscons.c                                 1.409.2.1
- - - -------------------------------------------------------------------------

VII. References

Version: GnuPG v1.2.6 (FreeBSD)

- - -----END PGP SIGNATURE-----

- - --------------------------END INCLUDED TEXT--------------------

- ----------------------------------------------------------------------------------

For additional information or assistance, please contact the HELP Desk by 
telephone or Not Protectively Marked information may be sent via 
EMail to: uniras@xxxxxxxxxxxx

Office Hours:
Mon - Fri: 08:30 - 17:00 Hrs
Tel: +44 (0) 870 487 0748 Ext 4511
Fax: +44 (0) 870 487 0749

Outside of Office Hours:
On Call Duty Officer:
Tel: +44 (0) 870 487 0748 and follow the prompts

- ----------------------------------------------------------------------------------
UNIRAS wishes to acknowledge the contributions of FreeBSD for the information 
contained in this Briefing. 
- ----------------------------------------------------------------------------------
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. 
- ----------------------------------------------------------------------------------
<End of UNIRAS Briefing>

Version: PGP 8.0