GLSA-201612-01 : GnuPG: RNG output is predictable

This script is Copyright (C) 2016-2017 Tenable Network Security, Inc.


Synopsis :

The remote Gentoo host is missing one or more security-related
patches.

Description :

The remote host is affected by the vulnerability described in GLSA-201612-01
(GnuPG: RNG output is predictable)

A long standing bug (since 1998) in Libgcrypt (see “GLSA 201610-04”
below) and GnuPG allows an attacker to predict the output from the
standard RNG. Please review the “Entropy Loss and Output Predictability
in the Libgcrypt PRNG” paper below for a deep technical analysis.

Impact :

An attacker who obtains 580 bytes of the random number from the standard
RNG can trivially predict the next 20 bytes of output.
This flaw does not affect the default generation of keys, because
running gpg for key creation creates at most 2 keys from the pool. For a
single 4096 bit RSA key, 512 bytes of random are required and thus for
the second key (encryption subkey), 20 bytes could be predicted from the
the first key.
However, the security of an OpenPGP key depends on the primary key
(which was generated first) and thus the 20 predictable bytes should not
be a problem. For the default key length of 2048 bit nothing will be
predictable.

Workaround :

There is no known workaround at this time.

See also :

http://formal.iti.kit.edu/~klebanov/pubs/libgcrypt-cve-2016-6313.pdf
https://security.gentoo.org/glsa/201610-04
https://security.gentoo.org/glsa/201612-01

Solution :

All GnuPG 1 users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose '>=app-crypt/gnupg-1.4.21'

Risk factor :

Medium / CVSS Base Score : 5.0
(CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N)

Family: Gentoo Local Security Checks

Nessus Plugin ID: 95516 ()

Bugtraq ID:

CVE ID: CVE-2016-6313

Ready to Amp Up Your Nessus Experience?

Get Nessus Professional to scan unlimited IPs, run compliance checks & more

Buy Nessus Professional Now