[SECURITY] [DLA 1560-1] gnutls28 security update

2018-10-30T16:34:24
ID DEBIAN:DLA-1560-1:55C8D
Type debian
Reporter Debian
Modified 2018-10-30T16:34:24

Description

Package : gnutls28 Version : 3.3.30-0+deb8u1 CVE ID : CVE-2018-10844 CVE-2018-10845 CVE-2018-10846

A set of vulnerabilities was discovered in GnuTLS which allowed attackers to do plain text recovery on TLS connections with certain cipher types.

CVE-2018-10844

It was found that the GnuTLS implementation of HMAC-SHA-256 was
vulnerable to a Lucky thirteen style attack. Remote attackers
could use this flaw to conduct distinguishing attacks and
plaintext-recovery attacks via statistical analysis of timing data
using crafted packets.

CVE-2018-10845

It was found that the GnuTLS implementation of HMAC-SHA-384 was
vulnerable to a Lucky thirteen style attack. Remote attackers
could use this flaw to conduct distinguishing attacks and plain
text recovery attacks via statistical analysis of timing data
using crafted packets.

CVE-2018-10846

A cache-based side channel in GnuTLS implementation that leads to
plain text recovery in cross-VM attack setting was found. An
attacker could use a combination of "Just in Time" Prime+probe
attack in combination with Lucky-13 attack to recover plain text
using crafted packets.

For Debian 8 "Jessie", these problems have been fixed in version 3.3.30-0+deb8u1. It was found to be more practical to update to the latest upstream version of the 3.3.x branch since upstream's fixes were rather invasive and required cipher list changes anyways. This will facilitate future LTS updates as well.

This change therefore also includes the following major policy changes, as documented in the NEWS file:

  • ARCFOUR (RC4) and SSL 3.0 are no longer included in the default priorities list. Those have to be explicitly enabled, e.g., with a string like "NORMAL:+ARCFOUR-128" or "NORMAL:+VERS-SSL3.0", respectively.

  • The ciphers utilizing HMAC-SHA384 and SHA256 have been removed from the default priority strings. They are not necessary for compatibility or other purpose and provide no advantage over their SHA1 counter-parts, as they all depend on the legacy TLS CBC block mode.

  • Follow closely RFC5280 recommendations and use UTCTime for dates prior to 2050.

  • Require strict DER encoding for certificates, OCSP requests, private keys, CRLs and certificate requests, in order to reduce issues due to the complexity of BER rules.

  • Refuse to import v1 or v2 certificates that contain extensions.

API and ABI compatibility is retained, however, although new symbols have been added. Many bugfixes are also included in the upload. See the provided upstream changelog for more details.

We recommend that you upgrade your gnutls28 packages and do not expect significant breakage.

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