CVE-2021-37460 in Axon PBX
Summary
by MITRE • 07/26/2021
Cross Site Scripting (XSS) exists in NCH Axon PBX v2.22 and earlier via /planprop?id= (reflected).
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Analysis
by VulDB Data Team • 07/28/2021
The vulnerability CVE-2021-37460 represents a cross site scripting flaw in NCH Axon PBX version 2.22 and earlier systems. This security weakness manifests through the /planprop?id= parameter which serves as an entry point for malicious script injection. The vulnerability is classified as reflected XSS, meaning that the malicious payload is reflected back to the user through the web application's response without proper input sanitization or output encoding. This particular implementation affects the web interface of the PBX system which is commonly used for telephony management and configuration. The affected version indicates that organizations running this legacy software are exposed to potential exploitation by attackers who can craft malicious URLs containing script payloads.
The technical exploitation of this vulnerability occurs when an attacker crafts a URL with a malicious script in the id parameter of the /planprop endpoint. When a victim clicks on such a crafted link and the application processes the request without adequate validation, the malicious script gets executed in the victim's browser context. This reflected nature means that the payload is not stored on the server but rather injected into the application's response dynamically. The vulnerability stems from insufficient input validation mechanisms and lack of proper output encoding for user-supplied parameters, creating an attack surface where untrusted data flows directly into the web application's response. According to CWE classification, this maps to CWE-79 which describes improper neutralization of input during web page generation, specifically the reflected variant.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform various malicious activities within the victim's browser session. Attackers can leverage this vulnerability to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious sites, or even harvest sensitive information from the PBX interface. Given that PBX systems typically contain sensitive telephony data including user credentials, call logs, and system configurations, the potential for data exfiltration or privilege escalation is significant. The vulnerability can be exploited in phishing campaigns where users are tricked into clicking malicious links, or through social engineering tactics that target administrators or end users with access to the system. This creates a persistent threat vector that could compromise the entire telephony infrastructure.
Organizations should implement immediate mitigations including input validation and output encoding for all user-supplied parameters, particularly those used in web application interfaces. The recommended approach involves sanitizing all input values before processing and ensuring that any data returned to the browser is properly encoded to prevent script execution. System administrators should upgrade to the latest version of NCH Axon PBX where this vulnerability has been patched, as version 2.23 and later releases include proper input validation mechanisms. Network segmentation and web application firewalls can provide additional layers of protection by monitoring and filtering malicious traffic patterns. Security awareness training for administrators and end users is crucial to prevent successful exploitation through social engineering attacks. The ATT&CK framework categorizes this vulnerability under T1059.007 for scripting and T1566 for phishing, indicating that exploitation typically follows reconnaissance and delivery phases. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web applications within the organization's infrastructure.