GNUTLS-SA-2013-1 (lucky thirteen) CVE-2013-0169 CVE-2013-1619

[Thijs Kinkhorst]

On Wed, February 6, 2013 10:22, Andreas Metzler wrote:
> Hello,
>
> sorry for the delayed pointer:
>
> -----------------------
> Nadhem Alfardan and Kenny Paterson devised an attack that recovers
> some bits of the plaintext of a GnuTLS session that utilizes that CBC
> ciphersuites, by using timing information.
>
> In order for the attack to work the client must operate as follows. It
> connects to a server, it sends some (encrypted) data that will be
> intercepted by the attacker, who will terminate the client's
> connection abnormally (i.e. the client will receive a premature
> termination error). The client should repeat that, multiple times.
> [...]
> How to mitigate the attack?
>
>     Do not enable the CBC ciphersuites, prefer ARCFOUR or GCM modes.
>     Upgrade to the latest GnuTLS version (3.1.7, 3.0.28, or 2.12.23).
> -----------------------
> http://www.isg.rhul.ac.uk/tls/
>
> Writeup for GnuTLS:
> http://nikmav.blogspot.be/2013/02/time-is-money-for-cbc-ciphersuites.html
>
> Debian's affected versions:
>
> Package  dist      Version up to     fixed in
> -----------------+----------------+----------------------------------
> gnutls26 exp       2.12.22-1         I will upload 2.12.23-1
> gnutls26 unstable  2.12.20-3         2.12.20-4
> gnutls26 testing   2.12.20-3         I will ask whether 2.12.20-4 can
>                                      propagate, otherwise I will make a
>                                      separate upload
> gnutls26 stable    2.8.6-1+squeeze2   -
>
> Sadly the patch does not apply directly to stable because 2.8.x is
> missing
> <http://gitorious.org/gnutls/gnutls/commit/32a7367601a3fda0aef07f5481c89e38d9c85b4a>
> As I am a) slightly ill and b) not a programmer I will not try my
> hands on this. :-(
>
> gnutls28 exp       3.1.6-1         3.1.7-1 (currently in NEW)
> gnutls28 unstable  3.0.22-2        not yet
> gnutls28 testing   3.0.20-3        not yet
> gnutls28 stable    N/A             N/A
>
> Regarding gnutls28 I will consult with debian-release.

Thanks for the detailed information. We were aware of the issue. Please
keep us posted on the fixed status of the variants in the various Debian
suites.


Cheers,
Thijs