CVE-2005-3172 in Windows
Summary
by MITRE
The WideCharToMultiByte function in Microsoft Windows 2000 before Update Rollup 1 for SP4 does not properly convert strings with Japanese composite characters in the last character, which could prevent the string from being null terminated and lead to data corruption or enable buffer overflow attacks.
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Analysis
by VulDB Data Team • 04/14/2019
The vulnerability described in CVE-2005-3172 represents a critical flaw in the Windows kernel's string conversion functionality that specifically affects the WideCharToMultiByte function implementation in Microsoft Windows 2000 systems prior to Update Rollup 1 for Service Pack 4. This issue stems from improper handling of Japanese composite characters, which are Unicode characters formed by combining multiple glyphs or diacritical marks into a single visual representation. The flaw manifests when processing strings containing these composite characters, particularly when they appear as the final character in a string sequence, creating a scenario where the function fails to properly null-terminate the converted output buffer.
The technical root cause of this vulnerability lies in the inadequate boundary checking and null termination logic within the WideCharToMultiByte function implementation. When processing Japanese composite characters, the function does not correctly account for the multi-byte nature of these characters in the conversion process, leading to scenarios where the destination buffer may not receive the proper null terminator required for safe string operations. This improper handling creates a condition where the function may write beyond the allocated buffer boundaries or fail to establish proper string termination, resulting in unpredictable behavior and potential exploitation opportunities.
The operational impact of this vulnerability extends beyond simple data corruption to encompass serious security implications including potential buffer overflow conditions that could be exploited by malicious actors. When the function fails to properly null-terminate strings, it creates opportunities for attackers to manipulate memory layouts and potentially execute arbitrary code through buffer overflow exploitation techniques. The vulnerability is particularly concerning in environments where Windows 2000 systems process user input containing Japanese text, as this scenario provides a realistic attack vector for exploitation. The flaw's potential to cause data corruption also means that legitimate applications relying on proper string handling may experience unexpected behavior or crashes, leading to service disruption.
This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, as the improper null termination can lead to memory corruption patterns that match these classifications. The attack surface is further expanded when considering the ATT&CK framework's T1059.007 technique related to command and scripting interpreter usage, as attackers may leverage this vulnerability to execute malicious commands through compromised applications. Additionally, the vulnerability demonstrates characteristics consistent with T1203, which involves exploitation of software vulnerabilities for privilege escalation, particularly in systems where applications may execute with elevated privileges. Microsoft's recognition of this issue through Update Rollup 1 for SP4 highlights the severity of the problem and the need for immediate remediation in affected environments.
The recommended mitigations for this vulnerability include immediate installation of the applicable Update Rollup 1 for Windows 2000 Service Pack 4, which provides the necessary code fixes to properly handle Japanese composite characters in string conversion operations. Organizations should also implement input validation measures to sanitize user data containing potentially problematic Unicode sequences and consider application-level buffer overflow protections. System administrators should monitor for any unusual behavior in applications processing international text and maintain comprehensive patch management procedures to ensure all vulnerable systems receive timely security updates. The vulnerability serves as a reminder of the importance of proper Unicode handling in security-critical system functions and the necessity of thorough testing of international character sets in security-critical code paths.