[ GLSA 200609-15 ] GnuTLS: RSA Signature Forgery

[Sune Kloppenborg Jeppesen <jaervosz () gentoo org>]

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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       < 1.4.4                            >= 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 ">=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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