CVE-2010-4208 in YUI
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Flash component infrastructure in YUI 2.5.0 through 2.8.1, as used in Bugzilla, Moodle, and other products, allows remote attackers to inject arbitrary web script or HTML via vectors related to uploader/assets/uploader.swf.
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Analysis
by VulDB Data Team • 09/28/2021
The vulnerability described in CVE-2010-4208 represents a critical cross-site scripting flaw within the Flash component infrastructure of the Yahoo User Interface (YUI) library versions 2.5.0 through 2.8.1. This security weakness specifically affects the uploader.swf file located in the uploader/assets directory of affected implementations, creating a pathway for remote attackers to execute malicious code within the context of users' browsers. The flaw stems from inadequate input validation and sanitization mechanisms within the Flash-based uploader component, which processes user-supplied data without proper security controls. This vulnerability impacts numerous web applications including Bugzilla and Moodle that rely on YUI for their user interface components, making it particularly dangerous due to the widespread adoption of these frameworks.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters that are processed by the Flash uploader.swf file. When users interact with the vulnerable component, the Flash application fails to properly sanitize or escape user-provided data before incorporating it into dynamic web content. This allows attackers to inject malicious JavaScript code or HTML fragments that execute in the victim's browser context. The vulnerability is classified as a classic XSS flaw under CWE-79, which specifically addresses improper neutralization of input during web page generation. The attack vector leverages the Flash component's ability to process and render user-supplied content without adequate security measures, creating a persistent threat that can be exploited across multiple applications using the affected YUI versions.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it enables attackers to perform a wide range of malicious activities within the context of authenticated users. Attackers can leverage this flaw to steal session cookies, redirect users to malicious sites, modify web page content, or even execute arbitrary commands on behalf of the victim. The vulnerability's presence in widely-used applications like Bugzilla and Moodle means that organizations with these systems in production are at significant risk of compromise. The attack surface is particularly broad since the affected Flash component is typically embedded within web applications that handle sensitive user data, making the potential for data exfiltration and privilege escalation substantial. Security professionals must consider that this vulnerability can be exploited in conjunction with other attack vectors to create more sophisticated threats.
Organizations should implement immediate mitigations to address this vulnerability including updating to patched versions of YUI library components, implementing proper input validation and sanitization measures, and deploying web application firewalls to detect and block malicious payloads. The recommended remediation strategy involves upgrading to YUI versions that have addressed this specific XSS vulnerability, typically versions beyond 2.8.1 where the Flash component infrastructure has been properly secured. Additionally, administrators should implement content security policies to limit the execution of inline scripts and ensure that user-supplied content is properly escaped before rendering. The vulnerability demonstrates the importance of secure coding practices in rich internet applications and highlights the need for comprehensive security testing of all components, particularly those involving Flash-based technologies. Organizations should also consider implementing monitoring and detection capabilities to identify potential exploitation attempts and maintain updated threat intelligence regarding similar vulnerabilities in third-party components.