[arch-security] [ASA-201608-18] libgcrypt: information disclosure

[Remi Gacogne]

Arch Linux Security Advisory ASA-201608-18
==========================================

Severity: Low
Date    : 2016-08-21
CVE-ID  : CVE-2016-6313
Package : libgcrypt
Type    : information disclosure
Remote  : Yes
Link    : https://wiki.archlinux.org/index.php/CVE

Summary
=======

The package libgcrypt before version 1.7.3-1 is vulnerable to
information disclosure.

Resolution
==========

Upgrade to 1.7.3-1.

# pacman -Syu "libgcrypt>=1.7.3-1"

The problem has been fixed upstream in version 1.7.3.

Workaround
==========

None.

Description
===========

Felix Dörre and Vladimir Klebanov from the Karlsruhe Institute of
Technology found a bug in the mixing functions of Libgcrypt's random
number generator: An attacker who obtains 4640 bits from the RNG can
trivially predict the next 160 bits of output. This bug exists since
1998 in all GnuPG and Libgcrypt versions.

Impact
======

A remote attacker, given access to enough entropy previously generated
from the RNG, can predict its output. Such access to enough entropy has
been found to be very unlikely in most situations, even for a local
attacker.

References
==========

https://lists.gnupg.org/pipermail/gnupg-announce/2016q3/000395.html
https://access.redhat.com/security/cve/CVE-2016-6313

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