Debian DLA-602-1 : gnupg security and hardening update

medium Nessus Plugin ID 93199


The remote Debian host is missing a security update.



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.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.


Upgrade the affected packages.

See Also

Plugin Details

Severity: Medium

ID: 93199

File Name: debian_DLA-602.nasl

Version: 2.6

Type: local

Agent: unix

Published: 8/30/2016

Updated: 1/11/2021

Supported Sensors: Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information


Risk Factor: Low

Score: 2.2


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N


Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:gnupg, p-cpe:/a:debian:debian_linux:gnupg-curl, p-cpe:/a:debian:debian_linux:gnupg-udeb, p-cpe:/a:debian:debian_linux:gpgv, p-cpe:/a:debian:debian_linux:gpgv-udeb, p-cpe:/a:debian:debian_linux:gpgv-win32, cpe:/o:debian:debian_linux:7.0

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 8/29/2016

Reference Information

CVE: CVE-2016-6313