CVE-2017-0931 in html-janitor
Summary
by MITRE
html-janitor node module suffers from a Cross-Site Scripting (XSS) vulnerability via clean() accepting user-controlled values.
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Analysis
by VulDB Data Team • 03/21/2023
The html-janitor node module vulnerability represents a critical cross-site scripting flaw that affects web applications relying on this library for HTML sanitization. This vulnerability specifically manifests within the clean() function which processes user-supplied input without adequate validation or sanitization measures. The issue stems from the module's inability to properly handle malicious script tags and javascript protocols embedded within HTML content, creating an attack surface that allows adversaries to inject harmful code into web applications. The vulnerability affects versions of html-janitor prior to 2.0.0, where the sanitization logic failed to adequately filter or escape user-controllable HTML input.
The technical implementation of this vulnerability occurs when applications pass user-generated content through the clean() method without proper input validation. The module's sanitization process does not sufficiently neutralize script execution contexts, allowing attackers to embed malicious javascript within HTML attributes, event handlers, or even within the body of HTML elements. This flaw enables attackers to bypass the intended security measures of the HTML sanitizer and execute arbitrary scripts in the context of the victim's browser. The vulnerability is particularly dangerous because it undermines the fundamental security assumption that sanitized HTML content is safe for display, creating a false sense of security for applications that depend on this library.
The operational impact of this vulnerability extends beyond simple script injection, potentially enabling full session hijacking, data exfiltration, and malicious payload delivery. An attacker could exploit this vulnerability to steal user session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. The vulnerability affects web applications that process user-generated content, including forums, comment systems, content management platforms, and any application that accepts HTML input from untrusted sources. The attack vector typically involves crafting malicious HTML input containing script tags or javascript protocols that bypass the sanitization process, ultimately executing in the victim's browser context and compromising the application's security posture.
Mitigation strategies for this vulnerability require immediate patching of the html-janitor module to version 2.0.0 or later where the sanitization logic has been significantly improved. Organizations should also implement additional defensive measures including input validation at multiple layers, content security policies to restrict script execution, and regular security auditing of third-party dependencies. The vulnerability aligns with CWE-79 which categorizes cross-site scripting flaws, and represents a clear violation of the principle of least privilege in web application security. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for script execution and T1566 for social engineering, as it enables attackers to deliver malicious payloads through compromised web applications. Regular dependency monitoring and automated security scanning should be implemented to prevent similar vulnerabilities from being introduced into applications through third-party libraries.