CVE-2018-15892 in FreePBX
Summary
by MITRE
FreePBX 13 and 14 has SQL Injection in the DISA module via the hangup variable on the /admin/config.php?display=disa&view=form page.
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Analysis
by VulDB Data Team • 06/26/2020
The vulnerability CVE-2018-15892 represents a critical SQL injection flaw within the FreePBX 13 and 14 web interfaces that specifically affects the DISA (Direct Inward System Access) module. This vulnerability exists due to insufficient input validation and sanitization of user-supplied data within the hangup parameter of the configuration page. The DISA module is designed to provide direct access to internal phone systems, making it a prime target for attackers seeking unauthorized system access and potential privilege escalation. The affected endpoint /admin/config.php?display=disa&view=form processes user input without proper sanitization, creating a pathway for malicious actors to inject arbitrary SQL commands into the backend database.
The technical exploitation of this vulnerability occurs when an attacker submits malicious input through the hangup variable parameter, which is then directly incorporated into SQL queries executed by the FreePBX application. This flaw falls under CWE-89 which specifically addresses SQL injection vulnerabilities where untrusted data is used in SQL commands without proper sanitization. The vulnerability allows for arbitrary code execution and database manipulation, potentially enabling attackers to extract sensitive information, modify system configurations, or escalate privileges within the telephony infrastructure. The lack of proper parameterized queries or input validation means that attackers can craft malicious payloads that bypass authentication mechanisms and directly interact with the underlying database system.
The operational impact of this vulnerability extends beyond simple data theft, as FreePBX systems often serve as central communication hubs for enterprise networks and organizations. Successful exploitation could lead to complete system compromise, unauthorized access to call logs, user credentials, and telephony configurations, potentially enabling attackers to conduct eavesdropping, make unauthorized calls, or disrupt critical communication services. The vulnerability affects both FreePBX 13 and 14 versions, indicating a widespread issue across multiple releases of the platform. Organizations using this system face significant risk of unauthorized access to their telephony infrastructure, which could be leveraged as a foothold for broader network infiltration attacks. The attack surface is particularly concerning given that many organizations rely on FreePBX for critical business communications and may not have adequate network segmentation to contain potential lateral movement.
Mitigation strategies for this vulnerability should include immediate patching of affected FreePBX installations to the latest versions that contain proper input validation and sanitization measures. Organizations should implement network segmentation to isolate telephony systems from critical business networks and deploy web application firewalls to monitor and filter suspicious SQL injection attempts. The implementation of principle of least privilege access controls for the DISA module and regular security audits of telephony configurations should be enforced. Additionally, organizations should conduct comprehensive vulnerability assessments to identify any other potential injection points within their telephony infrastructure and ensure that all input parameters are properly validated and sanitized. This vulnerability aligns with ATT&CK technique T1071.004 which covers application layer protocol manipulation, and T1190 which addresses exploitation of remote services through injection attacks, emphasizing the need for robust input validation and secure coding practices in telephony web applications.