AOL, Avaya, MSN and Nortel VoIP phone vulnerabilities

Sipera VIPER Lab disclosed seven threat advisories for SIP-based soft phones from AOL, Avaya, MSN and Nortel, and four advisories for Avaya SIP-based hard phones. These threat advisories are in addition to previous VoIP hard phone, WiFi/dual-mode phone and general SIP vulnerabilities published this year by Sipera VIPER Lab. Vulnerabilities are posted at

The major threat advisories that affect these VoIP soft phones include:

— Resource exhaustion and buffer overflow attack vulnerabilities in some AOL Instant Messenger voice clients, which might cause denial of service and may allow a remote attacker to crash the IM and voice client.

— A buffer overflow vulnerability and a SIP parsing error in Avaya one-X Desktop Edition SIP soft phones, potentially allow a remote attacker to partially disable the phone, disconnect it from the server and crash the phone.

— A resource exhaustion attack vulnerability in some Microsoft MSN Messenger voice chat clients, which might cause denial of service.

— A buffer overflow vulnerability and an improper message parsing vulnerability in Nortel Networks PC Client SIP soft phones, which may allow a remote attacker to crash the phone.

Sipera VIPER Lab also announced additional VoIP hard phone advisories for Avaya 4602SW SIP phones, which are vulnerable to server impersonation, accepting SIP requests from random source IP addresses, open UDP port flooding and RTP port flooding. These vulnerabilities can expose the phones to call hijacking, malicious messaging, denial of service, and voice quality degradation.

“Soft phones provide great flexibility for communications but are very vulnerable to attacks. These not only pose threats to the VoIP system but also to the computing and network environments,” said Krishna Kurapati, Sipera founder/CTO and head of Sipera VIPER Lab. “Left unaddressed, these vulnerabilities can disrupt critical business and personal voice communications, negating the many advantages to VoIP. Sipera works with its customers and vendors to address these threats before they become a major issue.”