CVE-2008-4029 in XML Core Services
Summary
by MITRE
Cross-domain vulnerability in Microsoft XML Core Services 3.0 and 4.0, as used in Internet Explorer, allows remote attackers to obtain sensitive information from another domain via a crafted XML document, related to improper error checks for external DTDs, aka "MSXML DTD Cross-Domain Scripting Vulnerability."
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Analysis
by VulDB Data Team • 06/14/2025
The CVE-2008-4029 vulnerability represents a critical cross-domain scripting flaw in Microsoft XML Core Services 3.0 and 4.0 that specifically affects Internet Explorer implementations. This vulnerability stems from inadequate error handling mechanisms when processing external Document Type Definitions within XML documents, creating a pathway for malicious actors to bypass standard web security restrictions. The flaw operates by exploiting the way MSXML handles error conditions during external DTD processing, allowing attackers to construct specially crafted XML documents that can retrieve sensitive information from different domains than the one hosting the vulnerable application.
The technical implementation of this vulnerability leverages the XML parsing behavior of MSXML components to execute cross-domain requests that should normally be restricted by browser security policies. When Internet Explorer processes an XML document containing external DTD references, the flawed error handling mechanism fails to properly validate or restrict access to resources from different origins. This creates a scenario where an attacker can craft XML content that, when loaded by a victim's browser, triggers MSXML to attempt to fetch external resources from other domains, potentially exposing sensitive data through error messages or response content that bypasses normal cross-domain restrictions. The vulnerability specifically relates to how MSXML manages external entity references and error reporting, which should normally be contained within the originating domain but can be manipulated to reveal information across domain boundaries.
From an operational perspective, this vulnerability poses significant risks to web applications that rely on MSXML for XML processing, particularly those that process untrusted XML content from external sources. Attackers can exploit this flaw by creating malicious XML documents that, when viewed in Internet Explorer, cause the browser to make unauthorized cross-domain requests and potentially expose sensitive information such as cookies, session tokens, or other domain-specific data. The impact extends beyond simple information disclosure to potentially enable more sophisticated attacks including session hijacking or credential theft. This vulnerability affects organizations running older versions of Microsoft Office and Internet Explorer, making it particularly dangerous in enterprise environments where legacy systems remain operational. The attack vector is particularly insidious because it can be delivered through seemingly benign XML content that appears legitimate to users while silently executing malicious cross-domain operations.
The vulnerability aligns with CWE-200, which addresses "Information Exposure Through Error Message," and relates to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1566 for "Phishing" as attackers often deliver malicious XML through phishing campaigns. Organizations should implement immediate mitigations including updating to patched versions of MSXML, disabling external DTD processing in XML parsers, and implementing proper input validation for XML content. Network-based defenses such as web application firewalls can help detect and block malicious XML content, while user education regarding suspicious file attachments remains crucial. The vulnerability also highlights the importance of proper security configuration management and regular patch management processes, as this flaw existed in widely deployed software versions for extended periods. Additionally, organizations should consider implementing content security policies and strict cross-origin resource sharing controls to limit the potential impact of such vulnerabilities in their environments.