CVE-2019-19615 in Backup
Summary
by MITRE
Multiple XSS vulnerabilities exist in the Backup & Restore module \ v14.0.10.2 through v14.0.10.7 for FreePBX, as shown at /admin/config.php?display=backup on the FreePBX Administrator web site. An attacker can modify the id parameter of the backup configuration screen and embed malicious XSS code via a link. When another user (such as an admin) clicks the link, the XSS payload will render and execute in the context of the victim user's account.
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Analysis
by VulDB Data Team • 03/17/2020
The vulnerability identified as CVE-2019-19615 represents a critical cross-site scripting flaw within the Backup & Restore module of FreePBX versions 14.0.10.2 through 14.0.10.7. This issue resides in the administrative web interface at the specific endpoint /admin/config.php?display=backup, making it particularly dangerous as it targets the privileged administrator account. The vulnerability stems from insufficient input validation and output encoding within the backup configuration screen, specifically in how the system handles the id parameter. Attackers can craft malicious links that embed XSS payloads through manipulation of this parameter, creating a persistent threat vector that can compromise the entire system when executed.
The technical exploitation of this vulnerability follows a classic server-side parameter injection pattern that aligns with CWE-79 Cross-site Scripting flaws. The flaw occurs because the application fails to properly sanitize user input before rendering it within the web interface, allowing malicious code to be stored and subsequently executed in the context of legitimate user sessions. When an administrator or other privileged user clicks on the crafted malicious link, the XSS payload executes with the privileges of the victim user, potentially enabling complete system compromise. This vulnerability operates under the ATT&CK framework as a technique for initial access and privilege escalation through web application exploitation.
The operational impact of CVE-2019-19615 extends far beyond simple data theft, as it provides attackers with a pathway to execute arbitrary code within the FreePBX administrative context. Since the affected module handles backup configurations, successful exploitation could lead to unauthorized system modifications, data exfiltration, or complete system takeover. The vulnerability is particularly concerning because it requires minimal user interaction beyond clicking a link, making it highly effective for social engineering campaigns. The attack vector demonstrates the classic pattern of persistent XSS where malicious code is stored on the server and executed whenever the vulnerable page is accessed, creating a long-term threat that persists until the vulnerability is patched.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The primary solution involves applying the vendor-provided patch to upgrade FreePBX to version 14.0.10.8 or later, which includes proper input validation and output encoding for the affected parameter. Organizations should also implement network segmentation to limit access to the FreePBX administrative interface, enforce multi-factor authentication for administrative accounts, and conduct regular security assessments of web applications. Additionally, implementing Content Security Policy headers and regular input validation testing can prevent similar vulnerabilities from emerging in the future. The vulnerability highlights the importance of proper parameter handling in web applications and demonstrates how seemingly minor input validation gaps can create severe security implications that affect the entire system infrastructure.