Check Point Advisories

Digium Asterisk Multiple Products IAX2 Handshake Denial of Service (CVE-2008-1897)

Vulnerability
Protection

Check Point Reference:	CPAI-2008-290
Date Published:	19 Jul 2010
Severity:	Critical
Last Updated:	Monday 19 July, 2010
Source:
Industry Reference:	CVE-2008-1897
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?
Vulnerability Description	There exists a denial of service vulnerability in multiple Digium Asterisk products. The vulnerability is due to insufficient verification of ACK responses during IAX2 handshakes by the IAX2 protocol. A remote unauthenticated attacker may exploit this vulnerability by sending a crafted message to the target server. Successful attack could create a denial of service condition on the Asterisk service. Upon successful exploitation of the vulnerability, the attack can make the target asterisk server send a large amount of data to a target host being spoofed. This might cause resource exhaustion for both the asterisk server and the target. If the attack stops sending the attacks, the target will recover in a time frame of a few minutes.

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 Digium Asterisk Multiple Products IAX2 Handshake Denial of Service 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: VoIP Enforcement Violation.
Attack Information: Digium Asterisk multiple products IAX2 handshake denial of service