CVE-2003-0806 in Windows
Summary
by MITRE
Buffer overflow in the Windows logon process (winlogon) in Microsoft Windows NT 4.0 SP6a, 2000 SP2 through SP4, and XP SP1, when a member of a domain, allows remote attackers to execute arbitrary code.
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Analysis
by VulDB Data Team • 12/31/2024
The vulnerability described in CVE-2003-0806 represents a critical buffer overflow flaw within the Windows logon process known as winlogon.exe. This vulnerability specifically affects Microsoft Windows NT 4.0 Service Pack 6a, Windows 2000 Service Packs 2 through 4, and Windows XP Service Pack 1 when systems are configured as domain members. The flaw exists in the authentication handling mechanism of the Windows operating system, where improper input validation occurs during the logon process. The buffer overflow vulnerability arises when the winlogon component processes certain input parameters from network authentication requests, particularly those involving domain membership verification and credential validation. This vulnerability is particularly concerning because it allows remote attackers to execute arbitrary code with system-level privileges, effectively compromising the entire Windows system. The attack vector typically involves sending maliciously crafted authentication requests to the target system, which then triggers the buffer overflow condition in the winlogon process. The vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and specifically relates to the improper restriction of operations within the bounds of a memory buffer. According to ATT&CK framework, this vulnerability maps to T1068, which covers 'Exploitation for Privilege Escalation', and T1190, which involves 'Exploitation of Remote Services'. The operational impact of this vulnerability is severe as it provides attackers with complete system compromise capabilities, enabling them to establish persistent access, escalate privileges, and potentially move laterally within domain environments. The vulnerability affects systems that are domain-joined because the winlogon process handles domain authentication requests, making it a prime target for attackers seeking to exploit domain environments. The flaw is particularly dangerous because it does not require local access to exploit, making it a remote code execution vulnerability that can be leveraged from outside the network perimeter. When exploited successfully, the buffer overflow allows attackers to overwrite critical memory locations within the winlogon process, potentially leading to arbitrary code execution with the highest system privileges. The vulnerability has been classified as a high-severity issue due to its potential for system takeover and the relatively simple exploitation methods available to attackers. Organizations running affected versions of Windows are at significant risk of unauthorized access, data breaches, and complete system compromise. The exploitability of this vulnerability is enhanced by the fact that it affects widely deployed operating systems, making it a popular target for automated attacks. Microsoft addressed this vulnerability through security updates that corrected the input validation flaws in the winlogon component, requiring users to apply the appropriate service packs and security patches to remediate the issue. The vulnerability serves as a classic example of how authentication mechanisms can be exploited to gain system-level access, highlighting the importance of secure coding practices and proper input validation in system components that handle authentication data.
The technical nature of this buffer overflow vulnerability stems from improper bounds checking within the winlogon process when handling network authentication requests. The flaw occurs during the processing of authentication parameters that are received from domain controllers or other authentication servers, where the system fails to properly validate the length of incoming data before copying it into fixed-size buffers. This classic stack-based buffer overflow allows attackers to overwrite return addresses and control instruction pointers within the winlogon process, enabling code execution with elevated privileges. The vulnerability is particularly significant because it affects the core authentication infrastructure of Windows systems, making it a prime target for attackers seeking to compromise entire domain environments. The exploitability of this vulnerability is enhanced by the fact that it requires no special privileges to initiate and can be triggered through standard authentication protocols. Attackers can leverage this vulnerability to execute malicious code that may include backdoors, keyloggers, or other malware, potentially leading to complete system compromise. The remote nature of the attack means that systems can be compromised from outside the local network, increasing the attack surface and making the vulnerability particularly dangerous for organizations with exposed authentication services. The vulnerability demonstrates the critical importance of input validation in security-sensitive components, as even small flaws in authentication handling can lead to complete system compromise. Security researchers have noted that this vulnerability represents a common pattern in legacy Windows systems where buffer overflow issues were prevalent due to less stringent security coding practices of that era. The exploitation of this vulnerability aligns with ATT&CK techniques that focus on privilege escalation and remote service exploitation, making it a well-documented threat vector in cybersecurity assessments. Organizations that failed to apply the relevant security patches faced significant risks, as the vulnerability could be exploited by automated scanning tools and malware that specifically target these known weaknesses in Windows authentication systems. The remediation process required organizations to update their systems to supported service pack levels, which not only fixed this specific vulnerability but also addressed numerous other security issues present in the affected Windows versions. This vulnerability underscores the importance of maintaining up-to-date security patches and demonstrates how seemingly minor flaws in authentication components can have catastrophic consequences for entire network environments.