CVE-2003-0109 in IIS
Summary
by MITRE
Buffer overflow in ntdll.dll on Microsoft Windows NT 4.0, Windows NT 4.0 Terminal Server Edition, Windows 2000, and Windows XP allows remote attackers to execute arbitrary code, as demonstrated via a WebDAV request to IIS 5.0.
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2003-0109 represents a critical buffer overflow condition within the ntdll.dll library of Microsoft Windows operating systems including Windows NT 4.0, Windows NT 4.0 Terminal Server Edition, Windows 2000, and Windows XP. This flaw specifically manifests when processing WebDAV requests through Internet Information Services 5.0, creating a pathway for remote code execution that has profound implications for system security. The vulnerability stems from inadequate input validation within the Windows kernel-level library that handles system calls and provides essential services to applications running on the platform.
The technical implementation of this vulnerability occurs through a malformed WebDAV request that triggers an insufficient bounds checking mechanism in the ntdll.dll component. When IIS 5.0 receives such a request, it processes the data without proper validation of buffer boundaries, allowing an attacker to overwrite adjacent memory locations. This buffer overflow condition specifically affects the stack-based memory management within the Windows operating system, where the overflow can overwrite critical function return addresses and execution pointers. The flaw is classified under CWE-121 as a stack-based buffer overflow, which directly enables attackers to manipulate program execution flow and inject malicious code into the target system's memory space.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with complete system compromise capabilities across multiple Windows versions that were prevalent during the early 2000s. An attacker exploiting this vulnerability can gain unauthorized access to sensitive system resources, escalate privileges to system level, and potentially establish persistent backdoors within the compromised environment. The attack vector through WebDAV requests makes this vulnerability particularly dangerous in enterprise environments where IIS servers are commonly deployed, as it can be exploited without requiring any authentication or prior access to the system. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, representing a foundational attack pattern that enables further compromise of networked systems.
Mitigation strategies for this vulnerability require immediate patch deployment through Microsoft's security updates, specifically addressing the ntdll.dll buffer overflow condition in affected Windows versions. System administrators should implement network segmentation to limit exposure of IIS 5.0 servers to untrusted networks and disable unnecessary WebDAV functionality where possible. The implementation of intrusion detection systems and network monitoring tools can help identify suspicious WebDAV traffic patterns that may indicate exploitation attempts. Additionally, applying the principle of least privilege and implementing robust access controls can limit the potential damage if exploitation occurs. Organizations should also consider disabling WebDAV support entirely on servers that do not require it, as this removes the attack surface entirely. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing defense-in-depth strategies to protect against kernel-level exploits that can provide complete system compromise.