CVE-1999-0572 is a high-severity vulnerability affecting Windows 2000 systems, stemming from the association of .reg files with the Windows NT registry editor (regedit). The core issue is that .reg files, which are used to modify the Windows registry, can be exploited by attackers to perform Trojan Horse attacks. When a user opens a maliciously crafted .reg file, it can silently alter critical registry settings, potentially leading to full system compromise. The vulnerability allows remote attackers to execute arbitrary code with the privileges of the logged-in user without requiring authentication. The CVSS score of 9.3 reflects the critical impact on confidentiality, integrity, and availability, with network attack vector, medium attack complexity, and no authentication required. Although this vulnerability dates back to 1997 and targets Windows 2000, the fundamental risk remains relevant in legacy systems still running this OS or similar configurations. The lack of available patches increases the risk for unmitigated systems. Exploitation does not require user interaction beyond opening the .reg file, which can be delivered via email, downloads, or removable media, making social engineering a common attack vector. This vulnerability highlights the inherent risk in file associations that allow direct registry modifications without sufficient safeguards or user warnings.

For European organizations, the impact of CVE-1999-0572 can be significant if legacy Windows 2000 systems remain in use, particularly in industrial control environments, government agencies, or sectors with long hardware/software lifecycles. Successful exploitation can lead to unauthorized system configuration changes, installation of persistent malware, data breaches, and disruption of critical services. The compromise of registry settings can undermine system integrity and availability, potentially causing operational downtime. Given the high CVSS score, attackers could leverage this vulnerability to gain footholds within networks, escalate privileges, and move laterally. Although modern Windows versions have mitigations, organizations with legacy infrastructure or insufficient patch management are at risk. The threat also underscores the importance of controlling file execution policies and user privileges to prevent unauthorized registry modifications.

1. Immediate identification and isolation of any legacy Windows 2000 systems within the network to assess exposure. 2. Where possible, upgrade or decommission Windows 2000 systems to supported Windows versions with improved security controls. 3. Implement strict group policies to restrict execution and import of .reg files, especially from untrusted sources. 4. Employ application whitelisting and endpoint protection solutions that can detect and block unauthorized registry modifications. 5. Educate users about the risks of opening unsolicited .reg files and implement email filtering to block or quarantine suspicious attachments. 6. Use network segmentation to limit access to legacy systems and reduce the attack surface. 7. Regularly audit registry changes and monitor system logs for unusual activity indicative of exploitation attempts. 8. If legacy systems must remain operational, consider deploying host-based intrusion detection systems (HIDS) tailored to monitor registry integrity.