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AUSCERT External Security Bulletin Redistribution
ESB-2006.0683 -- [NetBSD]
Integer overflows in CID-keyed font parser
22 September 2006
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: XFree86
X11R7
Publisher: NetBSD
Operating System: NetBSD-current
NetBSD 4.0_BETA
NetBSD 3.0.*
NetBSD 3.0
NetBSD 2.1
NetBSD 2.0.*
NetBSD 2.0
Impact: Execute Arbitrary Code/Commands
Access: Existing Account
CVE Names: CVE-2006-3740 CVE-2006-3739
Ref: ESB-2006.0655
Original Bulletin:
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-021.txt.asc
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NetBSD Security Advisory 2006-021
=================================
Topic: Integer overflows in CID-keyed font parser
Version: NetBSD-current: source prior to September 13, 2006
NetBSD 4.0_BETA: affected
NetBSD 3.1_RC3: not affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
NetBSD 2.1: affected
NetBSD 2.0.*: affected
NetBSD 2.0: affected
pkgsrc: xorg-libs-6.9.0nb8 and earlier
XFree86-libs-4.4.0nb8 and earlier
Severity: Potential privilege escalation
Fixed: NetBSD-current: September 13, 2006
NetBSD-4 branch: September 16, 2006
(4.0 will include the fix)
NetBSD-3-0 branch: September 16, 2006
(3.0.2 will include the fix)
NetBSD-3 branch: September 16, 2006
(3.1 will include the fix)
NetBSD-2-1 branch: September 18, 2006
NetBSD-2-0 branch: September 18, 2006
NetBSD-2 branch: September 18, 2006
pkgsrc: xorg-libs-6.9.0nb9 corrects the issue
XFree86-libs-4.4.0nb9 corrects the issue
Abstract
========
There are integer overflows present in the CID-keys font parser as
supplied with both XFree86 and X11R7.0. This can potentially lead
to arbitrary code execution. These vulnerabilities can be triggered
by a user parsing untrusted CID encoded Type 1 fonts.
These vulnerabilities have been assigned CVE references CVE-2006-3739
and CVE-2006-3740.
Technical Details
=================
There are two separate integer overflows that are present:
* scan_cidfont() function when handling 'CMap' and 'CIDFont' font data.
* CIDAFM() function when handling AFM (Adobe Font Metric) files
Both vulnerabilities can potentially lead to arbitrary code execution.
Solutions and Workarounds
=========================
While X11R7.0 from X.Org is in both the HEAD and netbsd-4 branches it
is currently not integrated fully into the base distribution. No NetBSD
releases contain X11R7.0 binaries and as such it is not necessary to
rebuild anything from source. The instructions below will patch the
relevant X11R7.0 source files so that if users are experimenting with
X11R7.0 it will contain the necessary security fixes.
A possible temporary workaround for this issue is to disable Type 1
fonts in your X Server configuration. To do this under the Modules
section of the X Server configuration file comment out the line
containing:
Load "type1"
For X.Org the configuration file will be xorg.conf and for XFree86
it will be XF86config. This may impact the appearance of applications
run in X Windows.
XFree86-based X servers are included in the NetBSD base distribution,
and will need to be rebuilt. The following instructions describe how
to upgrade your XFree86 binaries by updating your source tree and
rebuilding and installing a new version of XFree86.
* NetBSD-current:
Systems running NetBSD-current dated from before 2006-09-13
should be upgraded to NetBSD-current dated 2006-09-14 or later.
The following files need to be updated from CVS HEAD:
xorg/lib/Xfont/src/Type1/afm.c
xorg/lib/Xfont/src/Type1/scanfont.c
xorg/lib/Xfont/src/Type1/util.c
xfree/xc/lib/font/Type1/afm.c
xfree/xc/lib/font/Type1/scanfont.c
xfree/xc/lib/font/Type1/util.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update xorg/lib/Xfont/src/Type1/afm.c
# cvs update xorg/lib/Xfont/src/Type1/scanfont.c
# cvs update xorg/lib/Xfont/src/Type1/util.c
# cvs update xfree/xc/lib/font/Type1/afm.c
# cvs update xfree/xc/lib/font/Type1/scanfont.c
# cvs update xfree/xc/lib/font/Type1/util.c
# make build
* NetBSD 3.*:
Systems running NetBSD 3.* sources dated from before
2006-09-16 should be upgraded from NetBSD 3.* sources dated
2006-09-17 or later.
The following files need to be updated from the
netbsd-3 or netbsd-3-0 CVS branch:
xfree/xc/lib/font/Type1/afm.c
xfree/xc/lib/font/Type1/scanfont.c
xfree/xc/lib/font/Type1/util.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update -r <branch_name> xfree/xc/lib/font/Type1/afm.c
# cvs update -r <branch_name> \
xfree/xc/lib/font/Type1/scanfont.c
# cvs update -r <branch_name> xfree/xc/lib/font/Type1/util.c
# make build
* NetBSD 2.*:
Systems running NetBSD 2.* sources dated from before
2006-09-18 should be upgraded from NetBSD 2.* sources dated
2006-09-19 or later.
The following files need to be updated from the
netbsd-2, netbsd-2-0 or netbsd-2-1 CVS branch:
xfree/xc/lib/font/Type1/afm.c
xfree/xc/lib/font/Type1/scanfont.c
xfree/xc/lib/font/Type1/util.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update -r <branch_name> xfree/xc/lib/font/Type1/afm.c
# cvs update -r <branch_name> \
xfree/xc/lib/font/Type1/scanfont.c
# cvs update -r <branch_name> xfree/xc/lib/font/Type1/util.c
# make build
Thanks To
=========
iDefense for co-ordinating the disclosure of this issue.
Revision History
================
2006-09-21 Initial release
More Information
================
Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2006-021.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2006, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2006-021.txt,v 1.4 2006/09/21 20:18:29 adrianp Exp $
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