CVE-2015-5667 in HTML-Scrubber Module
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the HTML-Scrubber module before 0.15 for Perl, when the comment feature is enabled, allows remote attackers to inject arbitrary web script or HTML via a crafted comment.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/22/2024
The CVE-2015-5667 vulnerability represents a critical cross-site scripting flaw within the HTML-Scrubber Perl module, specifically affecting versions prior to 0.15. This vulnerability arises from insufficient input validation and sanitization when processing user-supplied comments that are subsequently rendered in web applications. The flaw manifests when the comment feature is enabled, creating an attack vector that allows remote adversaries to inject malicious scripts or HTML code directly into the application's output stream. The 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 CWE top 25 list. Attackers can exploit this weakness by crafting malicious comment content that contains embedded script tags or other HTML elements designed to execute in the context of other users' browsers. The implications extend beyond simple data theft, as this vulnerability can enable session hijacking, defacement of web pages, and the execution of arbitrary commands on victim machines through the exploitation of the XSS vector.
The technical exploitation of this vulnerability occurs through the improper handling of user comments within the HTML-Scrubber module's processing pipeline. When comments are enabled and user input is not properly sanitized, the module fails to adequately filter or escape special characters that could be interpreted as HTML or JavaScript code. This processing gap creates a persistent XSS vulnerability where malicious payloads can be stored and subsequently executed whenever other users view the affected content. The vulnerability is particularly concerning because it operates at the input sanitization layer, meaning that even if downstream applications implement proper security measures, the insecure comment handling within HTML-Scrubber can still allow malicious code to propagate through the system. This flaw aligns with ATT&CK technique T1566.001 for Initial Access through Phishing, as attackers can craft malicious comments that, when viewed by unsuspecting users, execute malicious scripts in their browsers.
The operational impact of CVE-2015-5667 extends far beyond simple code injection, as it enables attackers to compromise entire web applications and user sessions. When exploited, this vulnerability can result in unauthorized access to user accounts, data exfiltration, and the potential for privilege escalation within affected applications. The attack surface is particularly broad since HTML-Scrubber is commonly used in web applications that handle user-generated content, including forums, comment systems, and content management platforms. Organizations using affected versions of the module face significant risk of data breaches and reputational damage, as attackers can leverage this vulnerability to steal session cookies, redirect users to malicious sites, or inject additional malicious content that persists in the application. The vulnerability also represents a significant risk to web application security postures, as it demonstrates the critical importance of proper input validation and sanitization at all layers of application processing. The specific nature of this vulnerability makes it particularly dangerous in environments where user comments are frequently displayed without adequate security controls, creating an environment where a single malicious comment can compromise multiple users.
Mitigation strategies for CVE-2015-5667 require immediate action to upgrade to HTML-Scrubber version 0.15 or later, which contains the necessary fixes for proper input sanitization. Organizations should also implement additional security controls including comprehensive input validation, output encoding, and Content Security Policy implementations to provide defense-in-depth measures against similar vulnerabilities. The fix typically involves enhanced sanitization routines that properly escape or remove potentially dangerous characters from user comments before they are processed or stored. Security teams should conduct thorough vulnerability assessments to identify all applications using affected versions of the module and ensure proper patching procedures are followed. Additionally, implementing web application firewalls and runtime protection mechanisms can provide additional layers of defense against exploitation attempts. Organizations should also consider implementing automated monitoring for suspicious comment patterns and establish incident response procedures specifically designed to handle XSS-related security events. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security libraries and the potential consequences of failing to address known security flaws in third-party components.