CVE-2021-4124 in janus-gateway
Summary
by MITRE • 12/16/2021
janus-gateway is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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Analysis
by VulDB Data Team • 12/22/2021
The janus-gateway vulnerability identified as CVE-2021-4124 represents a critical cross-site scripting flaw that undermines the security integrity of web-based communication systems. This vulnerability falls under the well-established CWE-79 category for Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly sanitize user input before incorporating it into web page content. The affected system processes user-provided data through the janus-gateway framework without adequate validation or sanitization mechanisms, creating an exploitable pathway for malicious actors to inject harmful scripts into web interfaces.
The technical implementation of this vulnerability occurs when the janus-gateway component fails to properly escape or filter user-supplied parameters that are subsequently rendered in web pages. This flaw typically manifests when the system accepts input through various communication channels such as signaling messages, session parameters, or user-generated content that gets embedded into HTML responses without proper encoding or sanitization. The vulnerability affects the web interface components that handle user interactions and session management, creating opportunities for attackers to execute malicious scripts in the context of authenticated users' browsers.
From an operational perspective, this cross-site scripting vulnerability presents significant risks to organizations utilizing janus-gateway for real-time communication services. Attackers can exploit this weakness to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious sites, or extract sensitive information from authenticated sessions. The impact extends beyond simple data theft as the vulnerability can enable full account compromise and potentially provide attackers with persistent access to communication infrastructure. The attack surface is particularly concerning given that janus-gateway is commonly used in VoIP systems, video conferencing platforms, and other real-time communication services where user trust and session integrity are paramount.
The exploitation of CVE-2021-4124 aligns with several techniques documented in the MITRE ATT&CK framework under the T1059.001 category for Command and Scripting Interpreter, specifically targeting web application interfaces. Security professionals should consider this vulnerability as part of a broader attack chain that could lead to privilege escalation, lateral movement, or data exfiltration within network environments. Organizations using janus-gateway should prioritize immediate remediation through input validation, output encoding, and proper sanitization of all user-supplied content. The mitigation strategy should include implementing Content Security Policy headers, deploying web application firewalls, and conducting comprehensive security testing of all web interfaces to prevent similar vulnerabilities in related systems. This vulnerability underscores the critical importance of input validation and output encoding practices as fundamental security controls that align with industry standards and best practices for preventing web-based attacks.