CVE-2020-7747 in lightning-server
Summary
by MITRE • 10/20/2020
This affects all versions of package lightning-server. It is possible to inject malicious JavaScript code as part of a session controller.
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Analysis
by VulDB Data Team • 11/21/2020
The vulnerability in question affects all versions of the lightning-server package and represents a critical cross-site scripting flaw that allows attackers to inject malicious javascript code through the session controller component. This vulnerability falls under the CWE-79 category of Cross-Site Scripting and specifically manifests as a server-side injection attack vector that bypasses normal input validation mechanisms. The session controller serves as a critical entry point where user-provided data is processed and potentially rendered back to clients without proper sanitization, creating an environment where malicious payloads can be executed in the context of other users' browsers.
The technical exploitation of this vulnerability occurs when an attacker manipulates session controller parameters to include javascript code that gets executed in the victim's browser context. This type of attack leverages the trust relationship between the web application and its users, allowing the malicious code to perform actions such as stealing session cookies, redirecting users to malicious sites, or performing unauthorized operations on behalf of the victim. The attack vector is particularly dangerous because it operates at the session management level, potentially compromising user authentication states and enabling privilege escalation attacks.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on lightning-server for their web applications. The attack can lead to complete session hijacking, data theft, and unauthorized access to protected resources. The vulnerability is particularly concerning in environments where the session controller handles user input directly without proper encoding or sanitization, as it can affect multiple users simultaneously if the malicious payload is injected into shared session data. This type of vulnerability is often classified under the ATT&CK technique T1566 for Phishing and T1071 for Application Layer Protocol, as it enables attackers to establish persistent access and exfiltrate sensitive information through compromised user sessions.
The remediation approach requires immediate implementation of proper input validation and output encoding mechanisms throughout the session controller component. Organizations should implement Content Security Policy headers to prevent unauthorized script execution, employ proper parameter sanitization techniques, and ensure all user-provided data is properly escaped before being processed or rendered. Additionally, regular security audits of session management components should be conducted to identify similar vulnerabilities, and the package should be updated to the latest version where this vulnerability has been patched. The fix should also include implementing proper access controls and monitoring mechanisms to detect anomalous session behavior that might indicate exploitation attempts, following the principle of least privilege and defense in depth strategies as recommended by cybersecurity frameworks.