CVE-2003-0817 in Internet Explorer
Summary
by MITRE
Internet Explorer 5.01 through 6 SP1 allows remote attackers to bypass zone restrictions and read arbitrary files via an XML object.
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability described in CVE-2003-0817 represents a critical security flaw in Microsoft Internet Explorer versions 5.01 through 6 Service Pack 1 that fundamentally undermines the browser's security model. This issue stems from improper handling of XML objects within the browser's security architecture, specifically affecting the zone restriction mechanisms that are designed to prevent cross-zone access between local and internet content. The vulnerability operates by exploiting a weakness in how Internet Explorer processes XML objects, allowing malicious remote attackers to circumvent the security boundaries that normally prevent local file system access from internet-based content.
The technical implementation of this flaw involves the manipulation of XML objects to exploit a loophole in Internet Explorer's security zone enforcement. When an XML object is processed, the browser fails to properly validate or restrict the access permissions, enabling attackers to construct malicious code that can traverse zone boundaries and access local files that should normally be protected from remote access. This occurs because the XML object processing code does not adequately enforce the security policies that typically prevent internet zone content from accessing local zone resources, creating an unauthorized access path that bypasses the fundamental security architecture of the browser.
The operational impact of this vulnerability is severe and far-reaching, as it enables attackers to perform unauthorized file access operations on vulnerable systems. Remote attackers can leverage this weakness to read arbitrary files from the local file system, potentially gaining access to sensitive information such as configuration files, user data, or system credentials. The vulnerability is particularly dangerous because it requires no local privilege escalation or user interaction beyond visiting a malicious website, making it a highly effective vector for remote exploitation. This capability directly violates the principle of least privilege and undermines the core security assumptions of the browser's zone-based security model.
From a cybersecurity perspective, this vulnerability aligns with CWE-264, which covers permissions, privileges, and access control issues, and demonstrates how XML processing can introduce security weaknesses into web browsers. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under the T1059.007 category for script-based execution and T1068 for local privilege escalation through application weaknesses. The vulnerability represents a classic example of how complex web technologies can introduce security gaps in otherwise well-designed security models, particularly when dealing with cross-domain or cross-zone object handling.
Mitigation strategies for this vulnerability primarily involve applying the official Microsoft security patches released for Internet Explorer 6 Service Pack 1 and subsequent versions. Organizations should ensure that all affected systems receive the necessary updates and consider implementing additional security measures such as browser hardening configurations, network-based restrictions, and monitoring for suspicious file access patterns. The vulnerability also highlights the importance of maintaining up-to-date security practices and the need for comprehensive security testing of web browser components, particularly those involving object processing and cross-zone access controls. Additionally, administrators should consider implementing security policies that restrict XML processing capabilities in web browsers where possible, and conduct regular security assessments to identify similar vulnerabilities in other browser components or applications.