Check Point Advisories

GnuTLS DistinguishedName Decoding Double Free (CVE-2015-6251)

Vulnerability
Protection

Check Point Reference:	CPAI-2015-1238
Date Published:	26 Oct 2015
Severity:	Critical
Last Updated:	Thursday 17 December, 2015
Source:	GnuTLS GNUTLS-SA-2015-3
Industry Reference:	CVE-2015-6251
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?	GnuTLS GnuTLS 3.3.x prior to 3.3.17 GnuTLS GnuTLS 3.4.x prior to 3.4.4
Vulnerability Description	A double-free vulnerability has been reported in GnuTLS. The vulnerability is due to an error within _gnutls_x509_dn_to_string() while processing very long Distinguished Name values in X.509 certificates. A remote, unauthenticated attacker can exploit this vulnerability by sending a crafted certificate to a vulnerable GnuTLS client or server application. Successful exploitation will cause the application execute arbitrary code while an unsuccessful exploit attempt may cause the application to terminate, resulting in a denial-of-service condition.

Protection Overview

This protection will detect and block attempts to exploit this vulnerability.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, click on Protection tab and select the version of your choice.

Security Gateway R80 / R77 / R75

In the IPS tab, click Protections and find the GnuTLS DistinguishedName Decoding Double Free protection using the Search tool and Edit the protection's settings.
Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name: SSL Enforcement Violation.
Attack Information: GnuTLS DistinguishedName Decoding Double Free