SUSE Security Announcement: gpg,liby2util signature checking problems (SUSE-SA:2006:009)
Posted on: 02/20/2006 07:12 PM

A security announcement from SUSE

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______________________________________________________________________________

SUSE Security Announcement

Package: gpg,liby2util
Announcement ID: SUSE-SA:2006:009
Date: Mon, 20 Feb 2006 18:00:00 +0000
Affected Products: SUSE LINUX 10.0
SUSE LINUX 9.3
Vulnerability Type: remote code execution
Severity (1-10): 9
SUSE Default Package: yes
Cross-References: CVE-2006-0455

Content of This Advisory:
1) Security Vulnerability Resolved:
gpg incorrect signature checking
Problem Description
2) Solution or Work-Around
3) Special Instructions and Notes
4) Package Location and Checksums
5) Pending Vulnerabilities, Solutions, and Work-Arounds:
See SUSE Security Summary Report.
6) Authenticity Verification and Additional Information

______________________________________________________________________________

1) Problem Description and Brief Discussion

With certain handcraftable signatures GPG was returning a 0 (valid
signature) when used on command-line with option --verify.

This only affects GPG version 1.4.x, so it only affects SUSE Linux
9.3 and 10.0. Other SUSE Linux versions are not affected.

This could make automated checkers, like for instance the patch file
verification checker of the YaST Online Update, pass malicious patch
files as correct.

This is tracked by the Mitre CVE ID CVE-2006-0455.

Also, the YaST Online Update script signature verification had used
a feature which was lost in gpg 1.4.x, making it possible to
supply any kind of script which would be thought correct. This would
also allow code execution.

Both attacks require an attacker either manipulating a YaST Online
Update mirror or manipulating the network traffic between the mirror
and your machine.

2) Solution or Work-Around

There is no known workaround, please install the update packages.

3) Special Instructions and Notes

None.

4) Package Location and Checksums

The preferred method for installing security updates is to use the YaST
Online Update (YOU) tool. YOU detects which updates are required and
automatically performs the necessary steps to verify and install them.
Alternatively, download the update packages for your distribution manually
and verify their integrity by the methods listed in Section 6 of this
announcement. Then install the packages using the command

rpm -Fhv <file.rpm>

to apply the update, replacing <file.rpm> with the filename of the
downloaded RPM package.


x86 Platform:

SUSE LINUX 10.0:
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/i586/gpg-1.4.2-5.2.i586.rpm
f1422c0264ff3e270a56d03d4b47e762
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/i586/liby2util-2.12.9-0.3.i586.rpm
9a6f3ee339303f3efd92121dedf441aa
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/i586/liby2util-devel-2.12.9-0.3.i586.rpm
b504c0cf0f84039018ae1ac90d2e5292

SUSE LINUX 9.3:
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/i586/gpg-1.4.0-4.2.i586.rpm
fffa34f3034effa188cbeb942473e200
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/i586/liby2util-2.11.7-0.3.i586.rpm
a321ab146d07c50cc69a91352ac28bf7
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/i586/liby2util-devel-2.11.7-0.3.i586.rpm
1215bcf8f061079dbe05b93b1d611818

Power PC Platform:

SUSE LINUX 10.0:
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/ppc/liby2util-2.12.9-0.3.ppc.rpm
287ef59b3aec2b9aaaba0e17a9cbba27
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/ppc/liby2util-devel-2.12.9-0.3.ppc.rpm
f0bd4524c50c5e0a5613f70393ba4489

x86-64 Platform:

SUSE LINUX 10.0:
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/x86_64/liby2util-2.12.9-0.3.x86_64.rpm
edcad55c6587b9322b5895f2e1ff3760
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/x86_64/liby2util-devel-2.12.9-0.3.x86_64.rpm
c6b4a827e8ab4dc6d14608ceeb3e3385

SUSE LINUX 9.3:
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/x86_64/liby2util-2.11.7-0.3.x86_64.rpm
7cd1425a429b4637b34aa675d4eeaa85
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/x86_64/liby2util-devel-2.11.7-0.3.x86_64.rpm
8d27157261b70a5bb51ab643d8dd1fe8

Sources:

SUSE LINUX 10.0:
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/src/gpg-1.4.2-5.2.src.rpm
5098f06cba2e38aa0b5181fb3f9cd7f3
ftp://ftp.suse.com/pub/suse/i386/update/10.0/rpm/src/liby2util-2.12.9-0.3.src.rpm
3107fb78311f00f01c484c1fa1ab26df

SUSE LINUX 9.3:
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/src/gpg-1.4.0-4.2.src.rpm
026b7d74d345815de958152305ffde09
ftp://ftp.suse.com/pub/suse/i386/update/9.3/rpm/src/liby2util-2.11.7-0.3.src.rpm
2663aecb5e77147aca6881bd92e570bb

______________________________________________________________________________

5) Pending Vulnerabilities, Solutions, and Work-Arounds:

See SUSE Security Summary Report.
______________________________________________________________________________

6) Authenticity Verification and Additional Information

- Announcement authenticity verification:

SUSE security announcements are published via mailing lists and on Web
sites. The authenticity and integrity of a SUSE security announcement is
guaranteed by a cryptographic signature in each announcement. All SUSE
security announcements are published with a valid signature.

To verify the signature of the announcement, save it as text into a file
and run the command

gpg --verify <file>

replacing <file> with the name of the file where you saved the
announcement. The output for a valid signature looks like:

gpg: Signature made <DATE> using RSA key ID 3D25D3D9
gpg: Good signature from "SuSE Security Team <security@suse.de>"

where <DATE> is replaced by the date the document was signed.

If the security team's key is not contained in your key ring, you can
import it from the first installation CD. To import the key, use the
command

gpg --import gpg-pubkey-3d25d3d9-36e12d04.asc

- Package authenticity verification:

SUSE update packages are available on many mirror FTP servers all over the
world. While this service is considered valuable and important to the free
and open source software community, the authenticity and the integrity of
a package needs to be verified to ensure that it has not been tampered
with.

There are two verification methods that can be used independently from
each other to prove the authenticity of a downloaded file or RPM package:

1) Using the internal gpg signatures of the rpm package
2) MD5 checksums as provided in this announcement

1) The internal rpm package signatures provide an easy way to verify the
authenticity of an RPM package. Use the command

rpm -v --checksig <file.rpm>

to verify the signature of the package, replacing <file.rpm> with the
filename of the RPM package downloaded. The package is unmodified if it
contains a valid signature from build@suse.de with the key ID 9C800ACA.

This key is automatically imported into the RPM database (on
RPMv4-based distributions) and the gpg key ring of 'root' during
installation. You can also find it on the first installation CD and at
the end of this announcement.

2) If you need an alternative means of verification, use the md5sum
command to verify the authenticity of the packages. Execute the command

md5sum <filename.rpm>

after you downloaded the file from a SUSE FTP server or its mirrors.
Then compare the resulting md5sum with the one that is listed in the
SUSE security announcement. Because the announcement containing the
checksums is cryptographically signed (by security@suse.de), the
checksums show proof of the authenticity of the package if the
signature of the announcement is valid. Note that the md5 sums
published in the SUSE Security Announcements are valid for the
respective packages only. Newer versions of these packages cannot be
verified.

- SUSE runs two security mailing lists to which any interested party may
subscribe:

suse-security@suse.com
- General Linux and SUSE security discussion.
All SUSE security announcements are sent to this list.
To subscribe, send an e-mail to
<suse-security-subscribe@suse.com>.

suse-security-announce@suse.com
- SUSE's announce-only mailing list.
Only SUSE's security announcements are sent to this list.
To subscribe, send an e-mail to
<suse-security-announce-subscribe@suse.com>.

For general information or the frequently asked questions (FAQ),
send mail to <suse-security-info@suse.com> or
<suse-security-faq@suse.com>.

=====================================================================
SUSE's security contact is <security@suse.com> or <security@suse.de>.
The <security@suse.de> public key is listed below.
=====================================================================
______________________________________________________________________________

The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular, the
clear text signature should show proof of the authenticity of the text.

SUSE Linux Products GmbH provides no warranties of any kind whatsoever
with respect to the information contained in this security advisory.

Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team <security@suse.de>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <build@suse.de>

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