GnuPG: ElGamal signing keys compromised and format string vulnerability — GLSA 200312-05

A bug in GnuPG allows ElGamal signing keys to be compromised, and a format string bug in the gpgkeys_hkp utility may allow arbitrary code execution.

Affected Packages

app-crypt/gnupg on all architectures
Affected versions <= 1.2.3-r4
Unaffected versions >= 1.2.3-r5

Background

GnuPG is a popular open source signing and encryption tool.

Description

Two flaws have been found in GnuPG 1.2.3.

First, ElGamal signing keys can be compromised. These keys are not commonly used, but this is "a significant security failure which can lead to a compromise of almost all ElGamal keys used for signing. Note that this is a real world vulnerability which will reveal your private key within a few seconds".

Second, there is a format string flaw in the 'gpgkeys_hkp' utility which "would allow a malicious keyserver in the worst case to execute an arbitrary code on the user's machine."

Impact

If you have used ElGamal keys for signing your private key can be compromised, and a malicious keyserver could remotely execute arbitrary code with the permissions of the user running gpgkeys_hkp.

Workaround

There is no known workaround at this time.

Resolution

All users who have created ElGamal signing keys should immediately revoke them. In addition, all Gentoo Linux machines with gnupg installed should be updated to use gnupg-1.2.3-r5 or higher:

 # emerge sync
 # emerge -pv '>=app-crypt/gnupg-1.2.3-r5'
 # emerge '>=app-crypt/gnupg-1.2.3-r5'
 # emerge clean

References

Release Date
December 12, 2003

Latest Revision
December 12, 2003: 01

Severity
minimal

Exploitable
unknown

Bugzilla entries