Mandrake Linux Security Advisory : gnupg (MDKSA-2003:109)
Medium Nessus Plugin ID 14091
SynopsisThe remote Mandrake Linux host is missing a security update.
DescriptionA severe vulnerability was discovered in GnuPG by Phong Nguyen relating to ElGamal sign+encrypt keys. From Werner Koch's email message :
'Phong Nguyen identified a severe bug in the way GnuPG creates and uses ElGamal keys for signing. 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.
Please *take immediate action and revoke your ElGamal signing keys*.
Furthermore you should take whatever measures necessary to limit the damage done for signed or encrypted documents using that key.'
And also :
'Note that the standard keys as generated by GnuPG (DSA and ElGamal encryption) as well as RSA keys are NOT vulnerable. Note also that ElGamal signing keys cannot be generated without the use of a special flag to enable hidden options and even then overriding a warning message about this key type. See below for details on how to identify vulnerable keys.'
MandrakeSoft urges any users who use the ElGamal sign+encrypt keys to immediately revoke these keys and discontinue use of them. Updated packages are provided that remove the ability to create these keys and to create signatures using these keys (thanks to David Shaw for writing the patch).
SolutionUpdate the affected gnupg package.