CVE-2003-0208 in Flash
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Macromedia Flash ad user tracking capability allows remote attackers to insert arbitrary Javascript via the clickTAG field.
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Analysis
by VulDB Data Team • 05/03/2019
The vulnerability identified as CVE-2003-0208 represents a critical cross-site scripting flaw within Macromedia Flash's advertising user tracking functionality. This security weakness specifically targets the clickTAG field implementation, which was designed to track user interactions with flash advertisements. The flaw allows malicious actors to inject arbitrary javascript code through this tracking parameter, creating a persistent security risk for web applications that utilize flash-based advertising. The vulnerability stems from inadequate input validation and sanitization within the flash player's handling of tracking parameters, particularly when processing clickTAG values that are meant to capture user click events.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious clickTAG parameter containing javascript code that gets executed within the context of a victim's browser session. This type of attack falls under the CWE-79 category of Cross-Site Scripting, specifically targeting the injection of malicious scripts through user-controllable input fields. The flaw demonstrates a classic lack of proper output encoding and input validation, where the flash player fails to sanitize user-supplied data before incorporating it into dynamic content generation. Attackers can leverage this vulnerability to execute malicious scripts in the victim's browser, potentially leading to session hijacking, data theft, or redirection to malicious websites.
The operational impact of CVE-2003-0208 extends beyond simple script injection, as it can enable more sophisticated attacks within the context of web advertising ecosystems. When exploited, this vulnerability allows attackers to manipulate the behavior of flash advertisements, potentially redirecting users to phishing sites or executing malicious payloads that persist across user sessions. The vulnerability affects web applications that rely on flash-based advertising frameworks, particularly those implementing user tracking mechanisms that utilize clickTAG parameters. This creates a significant risk for websites that handle sensitive user data or financial transactions, as the malicious scripts could capture keystrokes, steal session cookies, or modify page content. The vulnerability is particularly concerning in enterprise environments where flash-based advertising is commonly deployed across multiple applications and platforms.
Mitigation strategies for this vulnerability require immediate patching of affected flash player versions and implementation of proper input validation controls. Organizations should ensure that all flash content undergoes rigorous security testing, particularly around user-controllable input fields like clickTAG parameters. The recommended approach includes implementing strict input validation that filters or encodes special characters within tracking parameters, as well as employing content security policies to prevent execution of unauthorized javascript code. Additionally, network-level protections such as web application firewalls can help detect and block malicious clickTAG parameters before they reach vulnerable systems. This vulnerability highlights the importance of secure coding practices and input sanitization, aligning with ATT&CK technique T1566 for credential access through malicious advertisements. Organizations should also consider transitioning away from flash-based technologies due to their inherent security limitations and the discontinuation of flash player support by major browser vendors.