CVE-2000-0420 is a vulnerability in the default configuration of SYSKEY on Microsoft Windows 2000 systems. SYSKEY is a security feature designed to enhance the protection of the Windows Security Accounts Manager (SAM) database by encrypting it with a startup key. However, in Windows 2000's default configuration, the startup key used by SYSKEY is stored within the system registry itself. This design flaw allows an attacker with local access to the system to extract the startup key directly from the registry. Once the attacker obtains this key, they can decrypt data protected by the Encrypted File System (EFS), which relies on the startup key for securing file encryption keys. The vulnerability does not require user authentication (Au:N) and can be exploited with low attack complexity (AC:L) but requires local access (AV:L). The impact is critical as it compromises confidentiality, integrity, and availability (C:C/I:C/A:C) of encrypted data. No patches or updates are available to remediate this vulnerability, and there are no known exploits in the wild. The vulnerability was published in May 2000 and affects Windows 2000 systems specifically. Given the age of the product, this vulnerability is primarily relevant to legacy systems still in operation.

For European organizations still operating Windows 2000 systems, this vulnerability poses a significant risk to the confidentiality and integrity of sensitive data protected by EFS. An attacker with local access—such as an insider threat or someone who gains physical or remote access through other means—could extract the SYSKEY startup key from the registry and decrypt encrypted files. This could lead to unauthorized disclosure of sensitive information, data tampering, or disruption of business operations. The compromise of encrypted data could impact compliance with European data protection regulations such as GDPR, leading to legal and financial consequences. Additionally, the inability to patch this vulnerability increases the risk profile of affected systems. Organizations relying on legacy Windows 2000 environments in critical infrastructure, government, or industrial sectors may face heightened exposure due to the strategic importance of their data and systems.

Given that no patch is available, mitigation must focus on reducing exposure and limiting access. Specific recommendations include: 1) Immediate identification and inventory of all Windows 2000 systems within the organization. 2) Prioritize decommissioning or upgrading these systems to supported Windows versions that do not have this vulnerability. 3) Restrict local access to Windows 2000 machines strictly to trusted personnel and enforce strong physical security controls to prevent unauthorized access. 4) Implement network segmentation to isolate legacy systems from the broader corporate network, minimizing remote access vectors. 5) Employ endpoint detection and response (EDR) tools capable of monitoring for suspicious registry access or attempts to extract SYSKEY information. 6) Enforce strict access controls and auditing on systems that still require Windows 2000, including multi-factor authentication for any remote access. 7) Regularly back up encrypted data and verify backup integrity to enable recovery in case of compromise. 8) Educate IT staff about the risks of legacy systems and the importance of migration to supported platforms.