[ASA-201806-10] libgcrypt: private key recovery

[Morten Linderud]

Arch Linux Security Advisory ASA-201806-10
==========================================

Severity: High
Date    : 2018-06-16
CVE-ID  : CVE-2018-0495
Package : libgcrypt
Type    : private key recovery
Remote  : No
Link    : https://security.archlinux.org/AVG-719

Summary
=======

The package libgcrypt before version 1.8.3-1 is vulnerable to private
key recovery.

Resolution
==========

Upgrade to 1.8.3-1.

# pacman -Syu "libgcrypt>=1.8.3-1"

The problem has been fixed upstream in version 1.8.3.

Workaround
==========

None.

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

An implementation flaw has been discovered in multiple cryptographic
libraries that allows a side-channel based attacker to recover ECDSA or
DSA private keys. When these cryptographic libraries use the private
key to create a signature, such as for a TLS or SSH connection, they
inadvertently leak information through memory caches. An unprivileged
attacker running on the same machine can collect the information from a
few thousand signatures and recover the value of the private key.

Impact
======

An unprivileged user might be able to retrieve private keys on the
affected host.

References
==========

https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commitdiff;h=9010d1576e278a4274ad3f4aa15776c28f6ba965;hp=7b6c2afd699e889f5f054cc3d202a61bd0ee1dcf
https://lists.gnupg.org/pipermail/gnupg-announce/2018q2/000426.html
https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/
https://security.archlinux.org/CVE-2018-0495
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