FreeBSD VuXML: Documenting security issues in FreeBSD and the FreeBSD Ports Collection

PJSIP -- TCP denial of service in PJProject

Affected packages
pjsip <= 2.4.5
pjsip-extsrtp <= 2.4.5


VuXML ID e21474c6-031a-11e6-aa86-001999f8d30b
Discovery 2016-02-15
Entry 2016-04-15

The Asterisk project reports:

PJProject has a limit on the number of TCP connections that it can accept. Furthermore, PJProject does not close TCP connections it accepts. By default, this value is approximately 60.

An attacker can deplete the number of allowed TCP connections by opening TCP connections and sending no data to Asterisk.

If PJProject has been compiled in debug mode, then once the number of allowed TCP connections has been depleted, the next attempted TCP connection to Asterisk will crash due to an assertion in PJProject.

If PJProject has not been compiled in debug mode, then any further TCP connection attempts will be rejected. This makes Asterisk unable to process TCP SIP traffic.

Note that this only affects TCP/TLS, since UDP is connectionless.