GnuPG creates ElGamal keys for signing using insufficient entropy

2003-12-29T00:00:00
ID VU:940388
Type cert
Reporter CERT
Modified 2003-12-29T15:52:00

Description

Overview

Gnu Privacy Guard (GnuPG) is a cryptographic utility used to generate cryptographic keys and perform other cryptographic functions. A vulnerability in the way GnuPG generates ElGamal keys has been discovered. This vulnerability renders ElGamal signing key untrustworthy.

Description

A vulnerability in the algorithm to generate ElGamal sign+encrypt keys can permit an attacker to generate valid signatures without access to the private key. This vulnerability does not affect encrypt-only (type 16) ElGamal keys, only the ElGamal sign+encrypt key (type 20) when used to make a signature with a GnuPG version 1.0.2 or later.


Impact

A remote attacker can generate a valid signature without access to the private key.


Solution

Revoke your ElGamal signing keys. GnuPG has released a patch for version 1.2.3 or you can upgrade to version 1.2.4 or later.


Vendor Information

940388

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GNU Privacy Guard __ Affected

Updated: December 29, 2003

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please see the GnuPG advisory at <http://lists.gnupg.org/pipermail/gnupg-announce/2003q4/000276.html>

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group | Score | Vector
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Base | |
Temporal | |
Environmental | |

References

  • <http://www.secunia.com/advisories/10304/>
  • <http://www.securityfocus.com/bid/9115>
  • <http://www.secunia.com/advisories/10349/>
  • <http://www.secunia.com/advisories/10400/>
  • <http://www.secunia.com/advisories/10399/>

Acknowledgements

Thanks to Werner Koch for his advisory on this issue, and Phong Nguyen for reporting this vulnerability.

This document was written by Jason A Rafail.

Other Information

CVE IDs: | CVE-2003-0971
---|---
Severity Metric: | 6.33
Date Public: | 2003-11-27
Date First Published: | 2003-12-29
Date Last Updated: | 2003-12-29 15:52 UTC
Document Revision: | 7