CVE-2020-28847 in Valine
Summary
by MITRE • 04/05/2022
Cross Site Scripting (XSS) vulnerability in xCss Valine v1.4.14 via the nick parameter to /classes/Comment.
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Analysis
by VulDB Data Team • 04/08/2022
The CVE-2020-28847 vulnerability represents a cross site scripting flaw identified in the xCss Valine commenting system version 1.4.14. This vulnerability specifically manifests through the nick parameter within the /classes/Comment endpoint, creating a significant security risk for web applications that utilize this commenting framework. The issue stems from inadequate input validation and output sanitization mechanisms that fail to properly escape or filter user-supplied data before rendering it in web pages. This particular vulnerability falls under the CWE-79 category of Cross Site Scripting, which is classified as one of the most prevalent and dangerous web application security flaws in the industry. The vulnerability allows attackers to inject malicious scripts into web pages viewed by other users, potentially leading to session hijacking, credential theft, or other malicious activities.
The technical exploitation of this vulnerability occurs when an attacker submits a specially crafted nick parameter containing malicious javascript code to the vulnerable Comment class endpoint. When the application processes this input without proper sanitization and subsequently displays it in the user interface, the injected script executes in the context of other users' browsers. This type of vulnerability is particularly dangerous because it can be leveraged to bypass the same origin policy that normally protects web browsers from cross-site attacks. The attack vector is typically executed through social engineering or by exploiting trust relationships, where users are unknowingly directed to malicious URLs containing the XSS payload. The vulnerability demonstrates a fundamental flaw in the application's data handling architecture, specifically in how it processes and renders user input without implementing proper security controls.
The operational impact of CVE-2020-28847 extends beyond simple script execution, as it can lead to comprehensive session hijacking and unauthorized access to user accounts. Attackers can craft payloads that steal cookies, session tokens, or other sensitive information from authenticated users, effectively allowing them to impersonate legitimate users within the application. This vulnerability also enables more sophisticated attacks such as defacement of web content, redirection to malicious sites, or the establishment of persistent backdoors through the injection of malicious scripts. The risk is particularly elevated in environments where the commenting system is widely used and trusted by users, as a single compromised comment can affect numerous visitors. From an ATT&CK framework perspective, this vulnerability maps to T1566 (Phishing) and T1059 (Command and Scripting Interpreter) techniques, as attackers can use the XSS flaw to deliver malicious payloads and establish persistent access to the target environment.
Mitigation strategies for CVE-2020-28847 require immediate implementation of proper input validation and output encoding mechanisms throughout the application's data processing pipeline. The most effective approach involves implementing comprehensive sanitization of all user inputs, particularly the nick parameter, using established libraries and frameworks that properly escape or encode data before rendering it in web contexts. Organizations should implement Content Security Policy (CSP) headers to add an additional layer of protection against script execution, while also ensuring that the application follows secure coding practices as outlined in OWASP Top 10 and other industry standards. The patch for this vulnerability should include proper validation of the nick parameter to reject potentially malicious inputs, combined with output encoding to prevent script execution even if malicious data somehow bypasses input validation. Regular security testing, including automated scanning and manual penetration testing, should be implemented to identify similar vulnerabilities in other components of the application. Additionally, developers should implement proper logging and monitoring mechanisms to detect and respond to potential exploitation attempts, ensuring that any suspicious activity related to the commenting system is promptly investigated and addressed.