Improper message parsing vulnerability in Nortel Networks PC Client may allow a remote attacker to crash the client

Overview

Nortel Networks PC Client SIP phone may not parse a malformed SIP header value allowing a remote attacker to crash the phone by sending a SIP message with such malformed header to the phone

Impact

Nortel Networks PC Client crashes when trying to parse malformed header causing denial of service to the user. Sending such malformed message to multiple phones may have denial of service impact on a larger scale

Description

Nortel Networks PC Client is a PC-based user application that provides a multimedia communications features to users. Improper message parsing vulnerability exists in SIP header parsing module of Nortel Networks PC Client which may allow a remote attacker to crash the client. This results in a complete denial of service to the user. Sending such message to multiple users may results in denial of service to large number of users. If restarted, the phone does function normally.

Solution

Phone SIP stack implementation should be patched to prevent exploiting such vulnerability.

Vendor Response: 

Nortel is aware of Security Advisory VIPER-2007-045 as issued by the Sipera Systems VIPER lab team. We are actively investigating the details in this Advisory to confirm that our latest SIP phones are not susceptible to this vulnerability. A formal Nortel Security Bulletin addressing this Advisory is expected to be available by July 31st.

 

For more information on any of these threat advisories, please email Sipera VIPER Lab at viper@sipera.com