Tags › CVE-2023-49786

Asterisk: denial of service via DTLS Hello packets during call initiation

• Fixed versions: 18.20.1, 20.5.1, 21.0.1,18.9-cert6
• Enable Security Advisory: https://www.enablesecurity.com/advisories/ES2023-01-asterisk-dtls-hello-race/
• Vendor Security Advisory: https://github.com/asterisk/asterisk/security/advisories/GHSA-hxj9-xwr8-w8pq
• Other references: CVE-2023-49786
• Tested vulnerable versions: 20.1.0
• Timeline:
  • Report date: 2023-09-27
  • Triaged: 2023-09-27
  • Fix provided for testing: 2023-11-09
  • Vendor release with fix: 2023-12-14
  • Enable Security advisory: 2023-12-15

TL;DR

When handling DTLS-SRTP for media setup, Asterisk is susceptible to Denial of Service due to a race condition in the hello handshake phase of the DTLS protocol. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack.