Debian Security Advisory

DLA-602-1 gnupg -- LTS security update

Date Reported:
29 Aug 2016
Affected Packages:
gnupg
Vulnerable:
Yes
Security database references:
In the Debian bugtracking system: Bug 834893.
In Mitre's CVE dictionary: CVE-2016-6313.
More information:
  • CVE-2016-6313

    Felix Doerre and Vladimir Klebanov from the Karlsruhe Institute of Technology discovered a flaw in the mixing functions of GnuPG's random number generator. An attacker who obtains 4640 bits from the RNG can trivially predict the next 160 bits of output.

    A first analysis on the impact of this bug for GnuPG shows that existing RSA keys are not weakened. For DSA and Elgamal keys it is also unlikely that the private key can be predicted from other public information.

  • Bypassing GnuPG key checking

    Weaknesses have been found in GnuPG signature validation that attackers could exploit thanks to especially forged public keys and under specific hardware-software conditions. While the underlying problem cannot be solved only by software, GnuPG has been strengthened, avoiding to rely on keyring signature caches when verifying keys. Potential specific attacks are not valid any more with the patch of GnuPG

  • Bypassing GnuPG key checking:

    Vrije Universiteit Amsterdam and Katholieke Universteit Leuven researchers discovered an attack method, known as Flip Feng Shui, that concerns flaws in GnuPG. Researchers found that under specific hardware-software conditions, attackers could bypass the GnuPG signature validation by using forged public keys. While the underlying problem cannot be solved only by software, GnuPG has been made more robust to avoid relying on keyring signature caches when verifying keys.

For Debian 7 Wheezy, these issues have been addressed in version 1.4.12-7+deb7u8.

We recommend that you upgrade your gnupg packages.

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS

For Debian 6 Squeeze, these issues have been fixed in gnupg version 1.4.12-7+deb7u8