An issue was discovered in channels/chan_sip.c in Sangoma Asterisk through 13.29.1, through 16.6.1, and through 17.0.0; and Certified Asterisk through 13.21-cert4. A SIP request can be sent to Asterisk that can change a SIP peer's IP address. A REGISTER does not need to occur, and calls can be hijacked as a result. The only thing that needs to be known is the peer's name; authentication details such as passwords do not need to be known. This vulnerability is only exploitable when the nat option is set to the default, or auto_force_rport.

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-18351
• https://www.asterisk.org/downloads/security-advisories
• http://downloads.asterisk.org/pub/security/AST-2019-006.html