CVE-2001-0665 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 and earlier allows remote attackers to cause certain HTTP requests to be automatically executed and appear to come from the user, which could allow attackers to gain privileges or execute operations within web-based services, aka the "HTTP Request Encoding vulnerability."
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Analysis
by VulDB Data Team • 04/07/2017
The CVE-2001-0665 vulnerability represents a critical security flaw in Internet Explorer 6 and earlier versions that fundamentally compromised the browser's ability to distinguish between legitimate user-initiated requests and maliciously crafted automated requests. This vulnerability exploited the browser's handling of HTTP request encoding, creating a scenario where attackers could manipulate the browser into executing HTTP requests that appeared to originate from the authenticated user. The flaw specifically targeted the way Internet Explorer processed certain encoding schemes in HTTP requests, allowing malicious actors to craft requests that would bypass normal security checks and appear as though they were legitimate user actions.
The technical mechanism behind this vulnerability stems from Internet Explorer's insufficient validation of HTTP request parameters and encoding methods. When processing web content, the browser failed to properly sanitize or validate encoded HTTP requests, particularly those involving special characters and encoding sequences that could be interpreted differently by the server. This weakness enabled attackers to construct malicious URLs or embedded content that would trigger automatic HTTP requests when the browser rendered the page. The vulnerability was particularly dangerous because it leveraged the browser's trust in the user context, making it appear as though the malicious actions were performed by the authenticated user rather than by an external attacker.
The operational impact of CVE-2001-0665 was severe and far-reaching, as it provided attackers with a means to perform privilege escalation and unauthorized operations within web-based services. Attackers could exploit this vulnerability to execute commands on behalf of authenticated users, potentially gaining access to sensitive data, modifying system configurations, or performing administrative actions within web applications. The vulnerability was particularly effective against web applications that relied on browser-based authentication or session management, as the malicious requests would appear to come from legitimate users with valid sessions. This created a significant risk for enterprise environments where users had elevated privileges and web applications handled sensitive business data.
This vulnerability aligns with several CWE categories including CWE-20, which addresses "Improper Input Validation," and CWE-89, which covers "Improper Neutralization of Special Elements used in an SQL Command." The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under T1059 for Command and Scripting Interpreter and T1566 for Phishing. Organizations affected by this vulnerability faced significant risks including data breaches, unauthorized access to sensitive systems, and potential compromise of entire web application infrastructures. The vulnerability highlighted the importance of proper input validation and the dangers of trusting browser-based request contexts without proper verification mechanisms.
Mitigation strategies for CVE-2001-0665 required immediate action including upgrading to Internet Explorer 7 or later versions where the vulnerability was addressed through improved HTTP request handling and validation. Organizations should have implemented additional security measures such as web application firewalls, enhanced input validation on server-side applications, and regular security audits of web-based services. The vulnerability also underscored the need for proper security training for developers and administrators to understand the risks associated with browser-based security contexts and the importance of validating all user inputs regardless of their source. Network segmentation and access controls became critical components in limiting the potential impact of such vulnerabilities within enterprise environments.