CVE-2010-4209 in YUI
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Flash component infrastructure in YUI 2.8.0 through 2.8.1, as used in Bugzilla 3.7.1 through 3.7.3 and 4.1, allows remote attackers to inject arbitrary web script or HTML via vectors related to swfstore/swfstore.swf.
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Analysis
by VulDB Data Team • 09/28/2021
The vulnerability identified as CVE-2010-4209 represents a critical cross-site scripting flaw within the Flash component infrastructure of the Yahoo User Interface (YUI) library version 2.8.0 through 2.8.1. This vulnerability specifically affects Bugzilla versions 3.7.1 through 3.7.3 and 4.1, creating a significant security risk for web applications that rely on these components for their functionality. The issue stems from improper input validation and sanitization within the swfstore/swfstore.swf Flash component, which serves as a storage mechanism for client-side data in web applications built using YUI. The vulnerability is categorized under CWE-79 as a classic cross-site scripting weakness, where malicious input is not properly escaped or filtered before being rendered in web pages, allowing attackers to execute arbitrary scripts in the context of the victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of Flash component parameters that are processed by the swfstore.swf file. Attackers can craft malicious payloads that, when processed by the vulnerable YUI infrastructure, get executed within the browser context of authenticated users. This typically involves injecting malicious JavaScript code or HTML content through parameters that are passed to the Flash component, which then gets stored and subsequently rendered without proper sanitization. The attack vector specifically targets the Flash-based storage mechanism, making it particularly dangerous because it leverages the trusted Flash environment to bypass standard web application security controls. The vulnerability is classified as a persistent XSS attack pattern within the MITRE ATT&CK framework under the technique T1566, where adversaries leverage web application vulnerabilities to inject malicious content that persists and executes in user browsers.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it can enable attackers to perform session hijacking, redirect users to malicious sites, or extract sensitive information from authenticated sessions. When exploited against Bugzilla installations, this vulnerability could allow attackers to access bug reports, user credentials, or other sensitive data that might be stored or displayed within the application's interface. The severity is amplified by the fact that YUI 2.8.0 through 2.8.1 was widely used in enterprise applications, meaning that organizations implementing these versions could be exposed to attacks targeting their web applications. The vulnerability demonstrates how legacy Flash-based components can create persistent security risks, particularly in environments where web applications have not been migrated away from older technologies that are no longer actively supported or maintained.
Organizations affected by this vulnerability should implement immediate mitigations including updating to patched versions of both YUI and Bugzilla, implementing proper input validation and sanitization for all parameters passed to Flash components, and deploying content security policies that restrict the execution of untrusted scripts. The recommended remediation approach includes upgrading to YUI 2.8.2 or later versions where the XSS vulnerability has been addressed, along with applying the corresponding Bugzilla patches that eliminate the vulnerable Flash component usage. Security teams should also consider implementing web application firewalls to detect and block suspicious parameters being passed to Flash components, and conduct thorough security assessments to identify other potential Flash-based vulnerabilities within their application infrastructure. Additionally, organizations should review their application architecture to minimize reliance on deprecated Flash technologies and migrate to modern, secure alternatives that provide equivalent functionality without the inherent security risks associated with Flash-based components.