SSL Server Accepts Weak Diffie-Hellman Keys

This script is Copyright (C) 2011-2014 Tenable Network Security, Inc.


Synopsis :

The remote SSL/TLS server accepts a weak Diffie-Hellman public value.

Description :

The remote SSL/TLS server accepts a weak Diffie-Hellman (DH) public
key value.

This flaw may aid an attacker in conducting a man-in-the-middle (MiTM)
attack against the remote server since it could enable a forced
calculation of a fully predictable Diffie-Hellman secret.

By itself, this flaw is not sufficient to set up a MiTM attack (hence
a risk factor of 'None'), as it would require some SSL implementation
flaws to affect one of the clients connecting to the remote host.

See also :

http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
http://polarssl.org/trac/wiki/SecurityAdvisory201101

Solution :

OpenSSL is affected when compiled in FIPS mode. To resolve this issue,
either upgrade to OpenSSL 1.0.0, disable FIPS mode or configure the
ciphersuite used by the server to not include any Diffie-Hellman key
exchanges.

PolarSSL is affected. To resolve this issue, upgrade to version
0.99-pre3 / 0.14.2 or higher.

If using any other SSL implementation, configure the ciphersuite used
by the server to not include any Diffie-Hellman key exchanges or
contact your vendor for a patch.

Risk factor :

None

Family: General

Nessus Plugin ID: 53360 ()

Bugtraq ID:

CVE ID: