Re: Fwd: How to tweak openSSL vulnerabilities CVE-2013-0169

[Alok Sharma]

Hi Steve,

     Thanks for reply. Do you have idea how CBC ciphers can be disabled?

Regards,
Alok

On Tue, Nov 12, 2013 at 8:23 PM, Dr. Stephen Henson <st...@openssl.org> wrote:

On Tue, Nov 12, 2013, Alok Sharma wrote:

> One of the openSSL vulnerabilities  is:
>
> CVE-2013-0169:
>
>   The TLS protocol 1.1 and 1.2 and the DTLS protocol 1.0 and 1.2, as used
> in OpenSSL, , do not properly consider timing side-channel attacks on a MAC
> check requirement during the processing of malformed CBC padding, which
> allows remote attackers to conduct distinguishing attacks and
> plaintext-recovery attacks via statistical analysis of timing data for
> crafted packets, aka the "Lucky Thirteen" issue.
>
>   All versions of OpenSSL are affected including 1.0.1c, 1.0.0j and 0.9.8x
>
>   Affected users should upgrade to OpenSSL 1.0.1d, 1.0.0k or 0.9.8y
>
> we use DTLS 1.0 protocol.
>
> Does anyone know of any setting in openssl configuration that can be
> tweaked to mitigate this vulnerability? E.g. a setting to not allow use of
> algorithms with CBC etc.?
>

The vulnerability is addressed in the latest OpenSSL releases.

If you disable CBC ciphers then you're only left with GCM and RC4. RC4 can't
be used with DTLS and GCM is only supported in DTLS 1.2.

Steve.
--
Dr Stephen N. Henson. OpenSSL project core developer.
Commercial tech support now available see: http://www.openssl.org
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[Alok Sharma]

Hi  Steve,

    I am also seeing AES along with GCM and RC4 in my search if I disable CBC. So can it guarantee that still client and server can communicate. Also if I use both end points as having same version of openssl than also there can be any problem.

Regards,
Alok