FreeSWITCH is an open-source telephony platform that is utilized globally in telecommunications infrastructures. It provides a scalable, multi-threaded, and cross-platform interface that is beneficial for VoIP applications, such as IVR systems, PBXs, and conferencing. Developers and organizations use FreeSWITCH to integrate telephony functions into software applications. By using widely available protocols and a modular design, FreeSWITCH offers flexibility and compatibility across different environments. The software is employed by enterprises for communication solutions, enabling efficient and high-quality telephony services. However, FreeSWITCH configurations need to be securely managed to prevent unauthorized access and potential exploitation.
The default credentials vulnerability in FreeSWITCH arises when the product ships with a configuration that includes hard-coded passwords. This issue affects versions 1.6.10 to 1.10.1, particularly when the mod_event_socket module is exposed with its default settings. If not addressed, unauthorized users can authenticate using the default password and potentially gain extensive control over the application. This vulnerability underscores the importance of changing default settings and passwords in telecommunication software. The vulnerability has been identified as CVE-2019-19492 and is considered critical, with a CVSS score of 9.8.
This vulnerability specifically allows unauthenticated remote attackers to authenticate with the default password "ClueCon" when the Event Socket Layer (ESL, TCP 8021) is accessible. Once authenticated, attackers can execute arbitrary FreeSWITCH API commands and OS commands, leading to a full system compromise. The technical essence of this flaw lies in the exposure of the ESL port and the failure to modify default credentials, which allows attackers to exploit these default settings to their advantage. Network administrators must ensure that the configuration file, event_socket.conf.xml, is adjusted to eliminate this default vulnerability.
If exploited, this vulnerability can allow attackers to run arbitrary commands on the FreeSWITCH system, hijack and intercept calls, read sensitive configuration files, and access credentials. This can lead to severe implications, including compromising telephony data, unauthorized command execution with system-level privileges, and the overall takeover of the telephony infrastructure. The impact highlights the critical nature of managing default configurations in security-sensitive applications like telephony services.
REFERENCES
- Change the default Event Socket password from "ClueCon" in the event_socket.conf.xml file.
- Configure the Event Socket service to bind to localhost (127.0.0.1) to prevent remote access.
- Implement an apply-inbound-acl to filter and restrict authorized access to the socket.
- Ensure that TCP port 8021 is not exposed to untrusted networks without proper authentication controls.
- Upgrade to FreeSWITCH 1.10.2 or later, where the Event Socket is bound to loopback by default.
- Regularly review and update firewall rules to minimize exposure to unnecessary services.
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