Condorlab

Asterisk – Vulnerability in pointer dereference in chan_sip while handling SDP negotiation


Advisory IDRSN-SIP-1630

Vulnerability Information

An issue was discovered in Asterisk Open Source through 13.27.0, 14.x and 15.x through 15.7.2, and 16.x through 16.4.0, and Certified Asterisk through 13.21-cert3. A pointer dereference in chan_sip while handling SDP negotiation allows an attacker to crash Asterisk when handling an SDP answer to an outgoing T.38 re-invite. To exploit this vulnerability an attacker must cause the chan_sip module to send a T.38 re-invite request to them. Upon receipt, the attacker must send an SDP answer containing both a T.38 UDPTL stream and another media stream containing only a codec (which is not permitted according to the chan_sip configuration).

Release Date

2019-07-02

Technical Information

An attacker could crash Asterisk when handling an SDP answer to an outgoing T.38 re-invite. Sending an SDP answer containing both a T.38 UDPTL stream and another media stream containing only a codec.

Solutions

The UCTM solution from RedShift Networks provides the industry’s first complete security solution developed to secure VOIP networks, endpoints and applications. His research team Condor-Labs.com is constantly looking for new attack patterns, advanced penetration testing methods, vulnerability identification and deployment of new signatures for constantly subscribed clients. For more information visit www.redshiftnetworks.com

External Resources

http://downloads.digium.com/pub/security/AST-2019-003.html
https://issues.asterisk.org/jira/browse/ASTERISK-28465

Common Vulnerabilities and Exposures (CVE)

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-13161