CVE-2006-6977 in FreeTextBox
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the "Basic Toolbar Selection" in FreeTextBox allows remote attackers to execute arbitrary JavaScript via the javascript: URI in the (1) href or (2) onmouseover attribute of the A HTML tag.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 10/09/2017
The vulnerability described in CVE-2006-6977 represents a critical cross-site scripting flaw within the FreeTextBox web-based rich text editor component. This vulnerability specifically targets the "Basic Toolbar Selection" functionality, which serves as a user interface element for inserting and manipulating hyperlinks within the editor's toolbar. The flaw exists in how the application processes and renders HTML attributes, creating an avenue for malicious actors to inject persistent JavaScript code into web pages that utilize the affected editor. The vulnerability manifests when user-supplied input containing javascript: URIs is processed without proper sanitization or validation, allowing attackers to execute arbitrary code in the context of victims' browsers.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within the FreeTextBox component. When users interact with the toolbar to create hyperlinks, the application fails to properly sanitize the href attribute values or onmouseover event handlers that contain javascript: protocol URLs. This represents a classic case of improper neutralization of special elements in the context of a web page, which directly maps to CWE-79 - Improper Neutralization of Input During Web Page Generation. The vulnerability specifically affects two distinct HTML attributes that are commonly used in web development for creating interactive links and hover effects, making it particularly dangerous as it can be exploited through multiple attack vectors within the same interface element.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform a wide range of malicious activities against users of affected web applications. Successful exploitation allows threat actors to steal session cookies, perform unauthorized actions on behalf of users, redirect victims to malicious websites, or even deface web content. The vulnerability is particularly concerning because it affects a toolbar component that is likely used across multiple pages and applications, potentially allowing attackers to compromise numerous web properties. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment, as it can be leveraged to deliver malicious JavaScript through seemingly legitimate web editing interfaces, making it easier to bypass security controls and user awareness.
Mitigation strategies for this vulnerability require immediate implementation of multiple defensive measures including input validation, output encoding, and proper attribute sanitization. Organizations should ensure that all user-supplied input containing HTML attributes is thoroughly validated and sanitized before being rendered in web pages, with special attention to javascript: URIs and event handlers. The implementation of Content Security Policy (CSP) headers can provide an additional layer of protection by restricting the sources from which scripts can be executed. Additionally, developers should update to patched versions of FreeTextBox where this vulnerability has been addressed, as the vulnerability is a known issue that was resolved in subsequent releases. Security teams should also implement regular vulnerability scanning and web application firewalls to detect and prevent exploitation attempts, while conducting security awareness training for developers to prevent similar issues in custom implementations that may use similar patterns to handle user input in rich text editors.