The Nortel UNIStim IP Softphone 2050, IP Phone 1140E, and additional Nortel products from the IP Phone, Business Communications Manager (BCM), Mobile Voice Client, and other product lines, allow remote attackers to block calls and force re-registration via a resume message to the Signaling Server that has a spoofed source IP address for the phone. NOTE: the attack is more disruptive if a new spoofed resume message is sent after each re-registration.

The Nortel UNIStim IP Softphone 2050, IP Phone 1140E, and additional Nortel products from the IP Phone, Business Communications Manager (BCM), and other product lines, use only 65536 different values in the 32-bit ID number field of an RUDP datagram, which makes it easier for remote attackers to guess the RUDP ID and spoof messages. NOTE: this can be leveraged for an eavesdropping attack by sending many Open Audio Stream messages.

The Nortel UNIStim IP Softphone 2050, IP Phone 1140E, and additional Nortel products from the IP Phone, Business Communications Manager (BCM), and other product lines allow remote attackers to eavesdrop on the physical environment via an Open Audio Stream message that enables "surveillance mode." NOTE: issues relating to a small ID number space can be leveraged to make this attack easier.