[CLA-2003:798] Conectiva Security Announcement - gnupg
Date: Tue, 9 Dec 2003 16:23:11 -0200
From: Conectiva Updates <[email protected]>
To: [email protected], [email protected],
Subject: [CLA-2003:798] Conectiva Security Announcement - gnupg
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CONECTIVA LINUX SECURITY ANNOUNCEMENT
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PACKAGE : gnupg
SUMMARY : GnuPG's ElGamal signing keys vulnerability
DATE : 2003-12-09 16:21:00
ID : CLA-2003:798
RELEVANT
RELEASES : 8, 9
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DESCRIPTION
GnuPG[1] is an OpenPGP-compliant tool for secure communication used
to, for example, sign emails, encrypt, decrypt and verify (signed)
data.
Phong Nguyen discovered[2] a vulnerability (CAN-2003-0971[3]) in the
way GnuPG deals with type 20 ElGamal sign+encrypt keys which allows
an attacker to recover the corresponding private key from a
signature. Other keys, such as ElGamal type 16 used only for
encryption, are not affected.
This is a serious vulnerability with immediate impact: all ElGamal
type 20 keys should be revoked and considered to be compromised, as
well as data signed or encrypted with such a key.
Please note that:
- by default, GnuPG does not generate this type of key;
- in order to create an ElGamal type 20 key, one must (in recent
versions of GnuPG) add the --expert command line option, and even
then a warning is given saying that this key should not be used. In
older versions, only the warning is given.
To identify the vulnerable type 20 ElGamal keys, look for the "G"
identifier in a key listing such as the example below:
pub 2048G/xxxxxxxx 2001-01-05 John Doe <[email protected]>
Other keys (including the ones identified by "g", lower case) are not
affected.
The packages provided with this update have a patch[4] created by
David Shaw which disables the creation of these keys and no longer
allows them to be used to create signatures.
SOLUTION
It is recommended that all GnuPG users upgrade their packages.
Additionally, users who have ever created ElGamal type 20
sign+encrypt keys should revoke them and consider them to be
compromised, as well as data signed or encrypted with such a key.
REFERENCES
1.http://www.gnupg.org/
2.http://lists.gnupg.org/pipermail/gnupg-announce/2003q4/000276.html
3.http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0971
4.http://lists.gnupg.org/pipermail/gnupg-announce/2003q4/000277.html
UPDATED PACKAGES
ftp://atualizacoes.conectiva.com.br/8/SRPMS/gnupg-1.0.7-1U80_3cl.src.rpm
ftp://atualizacoes.conectiva.com.br/8/RPMS/gnupg-1.0.7-1U80_3cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/8/RPMS/gnupg-doc-1.0.7-1U80_3cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/9/SRPMS/gnupg-1.2.3-19780U90_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/9/RPMS/gnupg-1.2.3-19780U90_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/9/RPMS/gnupg-doc-1.2.3-19780U90_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/9/RPMS/gnupg-keyserver-plugins-1.2.3-19780U90_1cl.i386.rpm
ADDITIONAL INSTRUCTIONS
The apt tool can be used to perform RPM packages upgrades:
- run: apt-get update
- after that, execute: apt-get upgrade
Detailed instructions reagarding the use of apt and upgrade examples
can be found at http://distro.conectiva.com.br/atualizacoes/#apt?idioma=en
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All packages are signed with Conectiva's GPG key. The key and instructions
on how to import it can be found at
http://distro.conectiva.com.br/seguranca/chave/?idioma=en
Instructions on how to check the signatures of the RPM packages can be
found at http://distro.conectiva.com.br/seguranca/politica/?idioma=en
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All our advisories and generic update instructions can be viewed at
http://distro.conectiva.com.br/atualizacoes/?idioma=en
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Copyright (c) 2003 Conectiva Inc.
http://www.conectiva.com
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subscribe: [email protected]
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