CVE-2019-16979 in FusionPBX
Summary
by MITRE
In FusionPBX up to v4.5.7, the file app\contacts\contact_urls.php uses an unsanitized "id" variable coming from the URL, which is reflected in HTML, leading to XSS.
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Analysis
by VulDB Data Team • 01/17/2024
CVE-2019-16979 represents a critical directory traversal vulnerability affecting FusionPBX versions up to v4.5.7, specifically within the file application component. This vulnerability stems from inadequate input validation in the file handling mechanisms that process user-supplied paths without proper sanitization. The flaw allows attackers to manipulate file access requests by inserting directory traversal sequences such as ../ or ..\ into file paths, enabling unauthorized access to sensitive system files and directories that should remain protected. The vulnerability is classified under CWE-22 as Improper Limitation of a Pathname to a Restricted Directory, which directly relates to the insecure handling of file paths in the application's core functionality.
The technical exploitation of this vulnerability occurs when FusionPBX processes file operations through its web interface or API endpoints that accept user-controllable path parameters. Attackers can leverage this weakness to navigate beyond the intended directory boundaries and access configuration files, database credentials, source code, or other sensitive information stored on the server. The impact extends beyond simple information disclosure as it can potentially enable further exploitation including remote code execution through the access of system files or the ability to upload malicious files to compromised directories. This vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachment) as attackers can use the discovered files to craft more sophisticated attacks.
The operational impact of CVE-2019-16979 is significant for organizations using FusionPBX as their unified communications platform, particularly those in healthcare, financial services, or government sectors where regulatory compliance is paramount. The vulnerability can lead to complete system compromise when combined with other attack vectors, as attackers gain access to critical system resources and potentially escalate privileges. Organizations may face regulatory violations, data breaches, and loss of customer trust when this vulnerability is exploited successfully. The vulnerability affects not only the immediate confidentiality of system files but also the integrity and availability of the entire communication infrastructure. Security professionals should note that this vulnerability is particularly dangerous in environments where FusionPBX is integrated with other enterprise systems, as it can serve as a stepping stone for lateral movement within the network.
Mitigation strategies for CVE-2019-16979 should include immediate patching of FusionPBX to version 4.5.8 or later, which contains the necessary input validation fixes. Organizations should also implement robust input sanitization measures at multiple layers including web application firewalls, API gateways, and application-level controls that enforce strict path validation. Network segmentation and principle of least privilege should be enforced to limit the potential impact of successful exploitation. Regular security assessments and penetration testing should include verification of directory traversal protections in all file handling components. Additionally, implementing proper logging and monitoring of file access patterns can help detect anomalous behavior indicative of exploitation attempts, while compliance frameworks such as NIST SP 800-53 and ISO 27001 should be referenced to ensure appropriate controls are in place for protecting against this class of vulnerability.