VOIP: Digium Asterisk Unnegotiated RTP Payload Type Denial-of-Service
A denial-of-service vulnerability has been reported in Digium Asterisk. The vulnerability is due to improper handling of RTP packets with unnegotiated Payload Types. A remote attacker could exploit this vulnerability by sending crafted RTP packets to the target server. Successful exploitation results in denial-of-service conditions on the target service.
Extended Description
A NULL pointer access issue was discovered in Asterisk 15.x through 15.2.1. The RTP support in Asterisk maintains its own registry of dynamic codecs and desired payload numbers. While an SDP negotiation may result in a codec using a different payload number, these desired ones are still stored internally. When an RTP packet was received, this registry would be consulted if the payload number was not found in the negotiated SDP. This registry was incorrectly consulted for all packets, even those which are dynamic. If the payload number resulted in a codec of a different type than the RTP stream (for example, the payload number resulted in a video codec but the stream carried audio), a crash could occur if no stream of that type had been negotiated. This was due to the code incorrectly assuming that a stream of that type would always exist.
Affected Products
Digium asterisk
Short Name
VOIP:SIP:DIGIUM-ASTRK-RTP-DOS
Severity
Major
Recommended
True
Recommended Action
Drop
Category
VOIP
Keywords
Asterisk CVE-2018-7285 Denial-of-Service Digium Payload RTP Type Unnegotiated bid:103149
Release Date
05/21/2018
Supported Platforms
srx-branch-12.3
srx-19.3
srx-branch-19.3
vsrx3bsd-19.2
srx-branch-19.4
vsrx-19.4
mx-12.3
mx-19.4
vmx-19.4
mx-19.3
vsrx3bsd-19.4
srx-19.4
vsrx-12.3
vmx-19.3
vsrx-19.2
srx-12.3
Sigpack Version
3337
Port
UDP/10000
False Positive
Unknown
Vendors
Digium
CVSS Score
5.0