Asterisk PJSIP Channel Driver Subscription DoS (AST-2014-004)
Medium Nessus Plugin ID 73022
SynopsisA telephony application running on the remote host is affected by a denial of service vulnerability.
DescriptionAccording to the version in its SIP banner, the version of Asterisk running on the remote host is potentially affected by a denial of service vulnerability.
A flaw exists in the PJSIP channel driver when handling 'SUBSCRIBE' requests. When Asterisk receives a 'SUBSCRIBE' request for a presence Event, with no Accept headers, it will try to access an invalid pointer to that header location. A remote attacker could exploit this flaw by sending a specially crafted request to cause the program to crash.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
SolutionUpgrade to Asterisk 12.1.0 or apply the appropriate patch listed in the Asterisk advisory.