(IBM Issues Fix for AIX) X Input Validation Flaw in ProcRenderAddGlyphs() Lets Local Users Obtain Memory Contents and Deny Service


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IBM SECURITY ADVISORY

First Issued: Wed Feb 22 15:00:38 CST 2012

The most recent version of this document is available here:

http://aix.software.ibm.com/aix/efixes/security/X_advisory2.asc
===============================================================================
VULNERABILITY SUMMARY

VULNERABILITY: Memory leak vulnerability in AIX X-server

PLATFORMS: AIX 6.1 and 7.1

SOLUTION: Apply the fix as described below.

THREAT: An attacker may execute arbitrary code with root privileges.

CVE Number: CVE-2010-4819

Reboot required? NO
Workarounds? NO
Protected by FPM? NO
Protected by SED? NO
===============================================================================
DETAILED INFORMATION

I. DESCRIPTION

An input sanitization flaw was found in the X.Org Render extension.
A malicious, authorized client could use this flaw to leak arbitrary
memory from the X.Org server process, or possibly crash the X.Org
server.

The following commands are vulnerable:

/usr/bin/X11/X

II. CVSS

CVSS Base Score: 4.6
CVSS Temporal Score: See http://xforce.iss.net/xforce/xfdb/70401 for the
current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P)

III. PLATFORM VULNERABILITY ASSESSMENT

To determine if your system is vulnerable, run the following command:

# lslpp -L X11.base.rte

The following filesets are vulnerable:

AIX Fileset Lower Level Upper Level
------------------------------------------------
X11.base.rte 6.1.4.0 6.1.4.3
X11.base.rte 6.1.5.0 6.1.5.2
X11.base.rte 6.1.6.0 6.1.6.17
X11.base.rte 6.1.7.0 6.1.7.2
X11.base.rte 7.1.0.0 7.1.0.16
X11.base.rte 7.1.1.0 7.1.1.2

IV. SOLUTIONS

A. APARS

IBM has assigned the following APARs to this problem:

AIX Level APAR number Availability
---------------------------------------------------
6.1.5 IV15633 sp9 TBD
6.1.6 IV15634 sp8 TBD
6.1.7 IV15747 sp4 TBD
7.1.0 IV15635 sp6 TBD
7.1.1 IV15746 sp4 TBD

Subscribe to the APARs here:

http://www.ibm.com/support/docview.wss?uid=isg1IV15633
http://www.ibm.com/support/docview.wss?uid=isg1IV15634
http://www.ibm.com/support/docview.wss?uid=isg1IV15747
http://www.ibm.com/support/docview.wss?uid=isg1IV15635
http://www.ibm.com/support/docview.wss?uid=isg1IV15746

By subscribing, you will receive periodic email alerting you
to the status of the APAR, and a link to download the fix once
it becomes available.

B. FIXES

Fixes are available. The fixes can be downloaded via ftp
from:

ftp://aix.software.ibm.com/aix/efixes/security/xorg_ifix.tar

The link above is to a tar file containing this signed
advisory, fix packages, and PGP signatures for each package.
The fixes below include prerequisite checking. This will
enforce the correct mapping between the fixes and AIX
Technology Levels.

AIX Level Interim Fix (*.Z)
-------------------------------------------------------------------
6.1.5 85215.610.120216.epkg.Z
6.1.6 85215.610.120216.epkg.Z
6.1.7 85215.610.120216.epkg.Z
7.1.0 85215.710.120216.epkg.Z
7.1.1 85215.710.120216.epkg.Z

To extract the fixes from the tar file:

tar xvf X_ifix2.tar
cd X_ifix2

Verify you have retrieved the fixes intact:

The checksums below were generated using the
csum -h SHA1" (sha1sum) command
and are as follows:

csum -h SHA1 (sha1sum) filename
------------------------------------------------------------------
6a52793eafea77b2c115645b1e978f746536dbdf 85215.610.120216.epkg.Z
02ac6bd1ff9f1d6bbc1e263afe86e09f71dff7e9 85215.710.120216.epkg.Z

To verify the sums, use the text of this advisory as input to
csum. For example:

csum -h SHA1 -i X_advisory2.asc

These sums should match exactly. The PGP signatures in the tar
file and on this advisory can also be used to verify the
integrity of the fixes. If the sums or signatures cannot be
confirmed, contact IBM AIX Security at
security-alert@austin.ibm.com and describe the discrepancy.

C. FIX AND INTERIM FIX INSTALLATION

IMPORTANT: If possible, it is recommended that a mksysb backup
of the system be created. Verify it is both bootable and
readable before proceeding.

To preview a fix installation:

installp -a -d fix_name -p all # where fix_name is the name of the
# fix package being previewed.
To install a fix package:

installp -a -d fix_name -X all # where fix_name is the name of the
# fix package being installed.

Interim fixes have had limited functional and regression
testing but not the full regression testing that takes place
for Service Packs; thus, IBM does not warrant the fully
correct functionality of an interim fix.

Interim fix management documentation can be found at:

http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html

To preview an interim fix installation:

emgr -e ipkg_name -p # where ipkg_name is the name of the
# interim fix package being previewed.

To install an interim fix package:

emgr -e ipkg_name -X # where ipkg_name is the name of the
# interim fix package being installed.

V. WORKAROUNDS

The X server can be disabled and then killed with the following
commands:

/usr/dt/bin/dtconfig -d
/usr/dt/bin/dtconfig -kill

The X Server can be restored after applying the fix with the
following commands:

/usr/dt/bin/dtconfig -e
/usr/bin/startsrc -s dtsrc

VI. CONTACT INFORMATION

If you would like to receive AIX Security Advisories via email,
please visit:

http://www.ibm.com/systems/support

and click on the "My notifications" link.

To view previously issued advisories, please visit:

http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd

Comments regarding the content of this announcement can be
directed to:

security-alert@austin.ibm.com

To request the PGP public key that can be used to communicate
securely with the AIX Security Team you can either:

A. Send an email with "get key" in the subject line to:

security-alert@austin.ibm.com

B. Download the key from a PGP Public Key Server. The key ID is:

0x28BFAA12

Please contact your local IBM AIX support center for any
assistance.

eServer is a trademark of International Business Machines
Corporation. IBM, AIX and pSeries are registered trademarks of
International Business Machines Corporation. All other trademarks
are property of their respective holders.

VII. REFERENCES:

Complete CVSS Guide: http://www.first.org/cvss/cvss-guide.html
On-line Calculator V2:
http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2
X-Force Vulnerability Database: http://xforce.iss.net/xforce/xfdb/70401
CVE-2010-4819: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-4819

*The CVSS Environment Score is customer environment specific and will
ultimately impact the Overall CVSS Score. Customers can evaluate the
impact of this vulnerability in their environments by accessing the links
in the Reference section of this Flash.

Note: According to the Forum of Incident Response and Security Teams
(FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry
open standard designed to convey vulnerability severity and help to
determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES
"AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE
RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY
VULNERABILITY.
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