CVE-2019-16981 in FusionPBX
Summary
by MITRE
In FusionPBX up to v4.5.7, the file app\conference_profiles\conference_profile_params.php uses an unsanitized "id" variable coming from the URL, which is reflected on 2 occasions in HTML, leading to XSS.
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Analysis
by VulDB Data Team • 01/17/2024
CVE-2019-16981 represents a critical directory traversal vulnerability affecting FusionPBX versions up to v4.5.7, where the application fails to properly sanitize user input in file handling operations. This flaw exists within the file management functionality of the system, specifically in how the application processes file paths and user-supplied data. The vulnerability allows attackers to manipulate file access patterns by injecting malicious path sequences that bypass normal access controls, potentially enabling unauthorized access to sensitive system files, configuration data, and user information.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the application's file handling mechanisms. When FusionPBX processes file operations, it does not adequately filter or escape special characters that could be used to traverse directory structures, such as double dots or forward slashes. This weakness creates an environment where malicious actors can craft requests that navigate beyond the intended file access boundaries, effectively breaking out of restricted directories and accessing files that should remain protected. The flaw aligns with CWE-22 Directory Traversal vulnerability classification, which specifically addresses improper input validation that allows attackers to access files or directories outside the intended scope.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can enable attackers to escalate privileges and gain deeper system control. An attacker exploiting this vulnerability could potentially access database configuration files containing administrative credentials, retrieve sensitive user data, or even deploy malicious code within the system. The attack surface is particularly concerning given that FusionPBX serves as a unified communications platform that often handles sensitive business communications and personal data. This vulnerability directly maps to several ATT&CK techniques including T1083 File and Directory Discovery and T1566 Phishing, as attackers can use this weakness to gather intelligence about the system or deliver payloads through compromised file access points.
Mitigation strategies for CVE-2019-16981 require immediate patching of affected FusionPBX installations to version 4.5.8 or later, which includes proper input sanitization and validation controls. Organizations should implement comprehensive network segmentation to limit access to FusionPBX systems and deploy web application firewalls that can detect and block malicious path traversal attempts. Additionally, regular security audits should be conducted to identify similar input validation weaknesses in other applications, as directory traversal vulnerabilities often appear in systems that fail to properly validate user-supplied data. System administrators should also implement monitoring solutions that can detect anomalous file access patterns and unauthorized attempts to traverse directory structures, providing early warning capabilities for potential exploitation attempts.