CVE-2003-0815 in Internet Explorer
Summary
by MITRE
Internet Explorer 6 SP1 and earlier allows remote attackers to bypass zone restrictions and read arbitrary files by (1) modifying the createTextRange method and using CreateLink, as demonstrated using LinkillerSaveRef, LinkillerJPU, and Linkiller, or (2) modifying the createRange method and using the FIND dialog to select text, as demonstrated using Findeath, aka the "Function Pointer Override Cross Domain" vulnerability.
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Analysis
by VulDB Data Team • 06/29/2021
The vulnerability described in CVE-2003-0815 represents a critical cross-domain security flaw in Internet Explorer 6 Service Pack 1 and earlier versions that fundamentally undermines the browser's security model. This issue exploits the browser's zone restriction mechanisms, which are designed to prevent malicious code from accessing local resources or communicating between different security domains. The vulnerability specifically targets the document object model's text manipulation methods, creating a pathway for attackers to bypass the security boundaries that separate trusted and untrusted content zones. The flaw demonstrates how seemingly benign DOM methods can be manipulated to create dangerous conditions that allow arbitrary file access across domain boundaries, effectively neutralizing the browser's core security architecture.
The technical implementation of this vulnerability leverages two distinct exploitation techniques that both rely on modifying JavaScript function pointers within the browser's text handling capabilities. The first method involves manipulating the createTextRange method and subsequently using the CreateLink functionality to establish cross-domain access points. The second approach modifies the createRange method and utilizes the FIND dialog's text selection capabilities to achieve similar results. These exploitation vectors demonstrate sophisticated understanding of Internet Explorer's internal object model and how function pointer overrides can be used to redirect execution flow. The attack methods utilize specific proof-of-concept tools like LinkillerSaveRef, LinkillerJPU, and Linkiller for the first technique, while Findeath serves as the demonstration tool for the second approach. Both techniques exploit fundamental weaknesses in how the browser validates cross-domain access requests when text manipulation functions are modified.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it provides attackers with the capability to read arbitrary files from the victim's local system. This creates a significant threat to user privacy and system security, as attackers could potentially access sensitive documents, configuration files, or other locally stored information that should remain protected from web-based access. The vulnerability affects not only individual users but also enterprise environments where Internet Explorer 6 was widely deployed, potentially allowing attackers to gather intelligence from corporate networks or access user credentials stored locally. The cross-domain nature of the exploit means that malicious websites could access resources from trusted domains, effectively breaking down the security boundaries that protect users from phishing attacks and other malicious activities. This vulnerability represents a classic example of how browser security models can be subverted through manipulation of core DOM functionality.
Mitigation strategies for CVE-2003-0815 require immediate action to address the underlying security issues in Internet Explorer 6 and earlier versions. The most effective solution involves upgrading to a supported browser version that has patched this vulnerability and implemented proper cross-domain security controls. Microsoft released patches for this vulnerability as part of their regular security updates, and organizations should ensure all systems are updated to the latest service packs and security updates. Additionally, administrators should implement strict browser security policies that disable potentially dangerous JavaScript methods or restrict cross-domain access through security zone configurations. Network-level protections such as web application firewalls can help detect and block exploitation attempts, while user education about avoiding suspicious websites and downloads remains crucial. This vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how legacy browser versions can contain fundamental security flaws that make them unsuitable for modern web usage. The issue aligns with CWE-284 Access Control and ATT&CK technique T1059 Command and Scripting Interpreter, emphasizing the need for comprehensive security measures that address both the technical vulnerability and the broader threat landscape.