CVE-2019-16965 in FusionPBX
Summary
by MITRE
resources/cmd.php in FusionPBX up to 4.5.7 suffers from a command injection vulnerability due to a lack of input validation, which allows authenticated administrative attackers to execute any commands on the host as www-data.
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Analysis
by VulDB Data Team • 01/17/2024
The vulnerability identified as CVE-2019-16965 affects FusionPBX versions up to 4.5.7 and represents a critical command injection flaw within the resources/cmd.php component. This issue arises from insufficient input validation mechanisms that fail to properly sanitize user-supplied data before processing. The vulnerability specifically impacts authenticated administrative users who possess sufficient privileges to access the cmd.php endpoint, creating a pathway for malicious command execution on the underlying host system.
The technical exploitation of this vulnerability occurs through the improper handling of input parameters within the cmd.php script, which directly incorporates user-provided values into system commands without adequate sanitization or escaping mechanisms. This flaw falls under the CWE-77 category of Command Injection, where attacker-controlled data is interpreted and executed as shell commands by the vulnerable application. The authentication requirement means that an attacker must first establish administrative access to the FusionPBX system, typically through credentials compromise or other authentication bypass techniques.
The operational impact of this vulnerability is severe and multifaceted, as it allows authenticated attackers to execute arbitrary commands with the privileges of the www-data user account, which typically runs the web server process. This privilege level provides access to the application's file system, database connections, and potentially other system resources that the web server can access. The attack vector directly aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, enabling attackers to perform reconnaissance, establish persistence, or escalate privileges within the compromised environment. The vulnerability essentially provides a backdoor for attackers to execute system-level commands and potentially gain broader access to the network infrastructure.
Mitigation strategies for CVE-2019-16965 should prioritize immediate patching of FusionPBX to versions beyond 4.5.7 where the command injection vulnerability has been addressed. Organizations should implement strict input validation and sanitization measures, particularly for any user-supplied parameters that may be passed to system commands. The principle of least privilege should be enforced by ensuring that the web server runs with minimal necessary permissions and that command execution capabilities are restricted. Network segmentation and monitoring solutions should be deployed to detect anomalous command execution patterns, while regular security assessments should verify that no unauthorized command execution capabilities exist within the system. Additionally, implementing proper access controls and multi-factor authentication for administrative accounts can significantly reduce the risk of unauthorized access to vulnerable components.