Asterisk REGISTER Request Contact URI Handling DoS (AST-2016-004)
Medium Nessus Plugin ID 90799
SynopsisA telephony application running on the remote host is affected by a denial of service vulnerability.
DescriptionAccording to its SIP banner, the version of Asterisk running on the remote host is either 13.x prior to 13.8.1 or 13.1-cert prior to 13.1-cert5. It is, therefore, affected by a flaw when processing incoming REGISTER requests if the REGISTER contains an overlong URI in the Contact header. An authenticated, remote attacker can exploit this to cause a denial of service condition.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
SolutionUpgrade to Asterisk version 13.8.1 / 13.1-cert5, or apply the appropriate patch according to the Asterisk advisory.