SSL Server Accepts Weak Diffie-Hellman Keys

Info Nessus Plugin ID 53360

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.

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.

See Also

https://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf

https://tls.mbed.org/tech-updates/security-advisories/polarssl-security-advisory-2011-01

Plugin Details

Severity: Info

ID: 53360

File Name: polarssl_dh_vuln.nasl

Version: 1.31

Type: remote

Family: General

Published: 2011/04/11

Updated: 2018/11/15

Dependencies: 56984

Risk Information

Risk Factor: Info

Vulnerability Information

Required KB Items: SSL/Supported

Exploited by Nessus: true