GLSA 200609-15 GnuTLS: RSA Signature Forgery
Posted on: 09/26/2006 05:25 PM

A new security update has been released for Gentoo Linux - GnuTLS: RSA Signature Forgery. Here the announcement:

Gentoo Linux Security Advisory GLSA 200609-15
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http://security.gentoo.org/
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Severity: Normal
Title: GnuTLS: RSA Signature Forgery
Date: September 26, 2006
Bugs: #147682
ID: 200609-15

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Synopsis
========

GnuTLS fails to handle excess data which could allow an attacker to
forge a PKCS #1 v1.5 signature.

Background
==========

GnuTLS is an implementation of SSL 3.0 and TLS 1.0.

Affected packages
=================

-------------------------------------------------------------------
Package / Vulnerable / Unaffected
-------------------------------------------------------------------
1 net-libs/gnutls lt; 1.4.4 gt;= 1.4.4

Description
===========

verify.c fails to properly handle excess data in
digestAlgorithm.parameters field while generating a hash when using an
RSA key with exponent 3. RSA keys that use exponent 3 are commonplace.

Impact
======

Remote attackers could forge PKCS #1 v1.5 signatures that are signed
with an RSA key, preventing GnuTLS from correctly verifying X.509 and
other certificates that use PKCS.

Workaround
==========

There is no known workaround at this time.

Resolution
==========

All GnuTLS users should update both packages:

# emerge --sync
# emerge --update --ask --verbose "gt;=net-libs/gnutls-1.4.4"

References
==========

[ 1 ] CVE-2006-4790
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4790

Availability
============

This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

http://security.gentoo.org/glsa/glsa-200609-15.xml

Concerns?
=========

Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
http://bugs.gentoo.org.

License
=======

Copyright 2006 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5



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