CVE-2021-41105: FreeSWITCH susceptible to Denial of Service via invalid SRTP packets

Vulnerability summary

CVE-2021-41105 is a high (CVSS 7.5) Improper Input Validation vulnerability in freeswitch. EPSS estimates a 2.52% chance of exploitation in the next 30 days, higher than 84.9% of scored vulnerabilities. 2 public exploits are recorded.

Timeline

1. 25-10-2021
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. When handling SRTP calls, FreeSWITCH prior to version 1.10.7 is susceptible to a DoS where calls can be terminated by remote attackers. This attack can be done continuously, thus denying encrypted calls during the attack. When a media port that is handling SRTP traffic is flooded with a specially crafted SRTP packet, the call is terminated leading to denial of service. This issue was reproduced when using the SDES key exchange mechanism in a SIP environment as well as when using the DTLS key exchange mechanism in a WebRTC environment. The call disconnection occurs due to line 6331 in the source file `switch_rtp.c`, which disconnects the call when the total number of SRTP errors reach a hard-coded threshold (100). By abusing this vulnerability, an attacker is able to disconnect any ongoing calls that are using SRTP. The attack does not require authentication or any special foothold in the caller's or the callee's network. This issue is patched in version 1.10.7.

• CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.