CVE-2004-0123 in Windows
Summary
by MITRE
Double free vulnerability in the ASN.1 library as used in Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, allows remote attackers to cause a denial of service and possibly execute arbitrary code.
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Analysis
by VulDB Data Team • 01/02/2025
The double free vulnerability identified as CVE-2004-0123 resides within the ASN.1 library component that forms part of Microsoft's operating systems including Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003. This vulnerability represents a critical memory management flaw that manifests when the library processes malformed ASN.1 encoded data structures, particularly affecting applications that rely on secure communication protocols such as SSL/TLS and LDAP. The vulnerability is classified under CWE-459 which specifically addresses incomplete cleanup issues in software systems, making it a prime target for exploitation by malicious actors seeking to disrupt system operations or gain unauthorized access.
The technical implementation of this vulnerability occurs when the ASN.1 parsing routine encounters specially crafted data that triggers an improper memory deallocation sequence. During normal operation, memory allocated for processing ASN.1 structures should be freed exactly once after use. However, the flaw allows an attacker to manipulate the parsing logic such that the same memory block gets freed twice, creating a condition known as a double free error. This memory corruption can occur when the library fails to properly validate input data before processing and executing memory deallocation routines. The vulnerability is particularly dangerous because it can be triggered remotely through network-based protocols that utilize ASN.1 encoding, such as LDAP queries or SSL/TLS handshakes.
From an operational impact perspective, this vulnerability presents significant risks to system availability and integrity across affected platforms. The primary consequence is a potential denial of service attack that can cause system crashes, application failures, or complete system hangs. However, the more severe implications arise from the possibility of arbitrary code execution, which can be achieved through careful exploitation of the memory corruption. Attackers can leverage this vulnerability to execute malicious code with the privileges of the affected application, potentially leading to full system compromise. The vulnerability affects all versions of Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, creating a substantial attack surface across enterprise environments that may still be running these legacy systems.
Mitigation strategies for this vulnerability should encompass multiple layers of security controls and system hardening measures. Microsoft released security patches through Windows Update and the Security Bulletin MS04-004 that addressed this specific issue by correcting the memory management logic in the ASN.1 library. Organizations should prioritize immediate deployment of these patches across all affected systems. Additionally, network segmentation and firewall rules should be implemented to restrict unnecessary access to services that utilize ASN.1 encoding, particularly LDAP and SSL/TLS services. Monitoring and logging should be enhanced to detect anomalous patterns in network traffic that might indicate exploitation attempts. The vulnerability also aligns with ATT&CK technique T1059 which covers command and scripting interpreter usage, and T1499 which addresses network denial of service attacks, making it a critical target for both preventive and detective security controls.