CVE-2008-3473 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 6 and 7 does not properly determine the domain or security zone of origin of web script, which allows remote attackers to bypass the intended cross-domain security policy, and execute arbitrary code or obtain sensitive information, via a crafted HTML document, aka "Event Handling Cross-Domain Vulnerability."
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Analysis
by VulDB Data Team • 05/26/2025
The vulnerability identified as CVE-2008-3473 represents a critical cross-domain security flaw in Microsoft Internet Explorer versions 6 and 7 that fundamentally undermines the browser's security model. This issue stems from the browser's improper handling of domain and security zone determination for web scripts, creating a pathway for malicious actors to circumvent the intended security boundaries that separate different domains and protect users from unauthorized code execution. The vulnerability specifically affects the event handling mechanisms within the browser's security architecture, allowing attackers to exploit the inconsistent domain resolution process during script execution. This flaw operates at the core of the browser's security zone classification system, which is designed to enforce strict boundaries between trusted and untrusted content sources. The vulnerability is particularly dangerous because it leverages the browser's own event handling infrastructure against itself, enabling attackers to craft malicious HTML documents that can bypass security policies that should normally prevent cross-domain script execution.
The technical implementation of this vulnerability exploits the way Internet Explorer determines the origin domain of scripts during event processing, particularly when dealing with dynamic content and event handlers. When a web page contains event handlers that reference objects or functions from different domains, the browser's domain validation mechanism fails to properly verify the security context, allowing scripts from untrusted domains to execute with elevated privileges. This occurs because the browser's security zone classification system does not adequately validate the domain of origin for event handlers, creating a window where malicious code can be injected and executed without proper security checks. The vulnerability specifically manifests when the browser attempts to resolve the domain context for event handlers, particularly those involving dynamic content or objects that may have been loaded from different security zones. This flaw represents a classic example of a security boundary violation where the system's own mechanisms become the attack vector, allowing unauthorized code execution that should normally be blocked by the browser's security model.
The operational impact of CVE-2008-3473 is severe and far-reaching, as it enables attackers to execute arbitrary code with the privileges of the user's current security context, potentially leading to complete system compromise. An attacker could craft a malicious HTML document that, when viewed in a vulnerable Internet Explorer version, would allow remote code execution on the target system. This vulnerability could be exploited through various attack vectors including phishing emails, malicious websites, or compromised web pages that deliver the malicious content. The ability to bypass cross-domain security policies means that attackers could access sensitive information stored in the user's browser session or system memory, potentially leading to data theft, credential compromise, or further system infiltration. The vulnerability is particularly concerning because it affects widely deployed versions of Internet Explorer, making it a prime target for widespread exploitation campaigns. The impact extends beyond simple code execution to include potential information disclosure, where attackers could access cookies, session tokens, or other sensitive data that should normally be protected by the browser's security model.
Mitigation strategies for this vulnerability primarily focus on immediate remediation through Microsoft security updates and patches that address the core domain validation flaw in Internet Explorer's security model. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive the necessary security updates as soon as they become available. Browser security configuration changes can also provide additional protection, including disabling script execution in potentially dangerous contexts and implementing stricter security zone policies. Network-level protections such as web application firewalls and content filtering systems can help detect and block malicious HTML content that attempts to exploit this vulnerability. The mitigation approach should align with established cybersecurity frameworks and best practices, including the principles outlined in the CWE (Common Weakness Enumeration) classification system which categorizes this vulnerability as a cross-domain security issue. Organizations should also consider implementing the ATT&CK framework's perspective on this vulnerability, recognizing it as a technique that leverages browser security model weaknesses to achieve privilege escalation and code execution. Additionally, user education and awareness programs should emphasize the importance of avoiding suspicious websites and email attachments that could contain malicious content designed to exploit this vulnerability.