CVE-1999-0595 is a vulnerability affecting Windows NT systems, specifically versions 3.5.1 and 4.0, and also noted in Windows 2000. The issue arises because the operating system does not clear the system page file (also known as the swap file) during shutdown. The page file is used to extend physical memory by swapping inactive pages of memory to disk. If this file is not cleared upon shutdown, sensitive information that was temporarily stored in memory and swapped out to disk can remain accessible on the disk. This residual data could include passwords, cryptographic keys, or other confidential information that was in use during the system's operation. Since the page file is stored on disk, an attacker with physical access to the machine or access to the disk image could potentially recover this sensitive information. The vulnerability has a CVSS score of 2.1, indicating a low severity level. The attack vector is local (AV:L), requiring local access, with low attack complexity (AC:L), no authentication required (Au:N), and impacts confidentiality only (C:P), with no impact on integrity or availability. There are no known exploits in the wild and no patches available, likely due to the age of the affected systems and the nature of the vulnerability. This vulnerability is primarily a data remanence issue, where sensitive data persists beyond its intended lifecycle due to improper clearing of memory artifacts on disk.

For European organizations, the impact of this vulnerability is generally low given the age of the affected operating systems (Windows NT 3.5.1, 4.0, and Windows 2000) which are largely obsolete and unsupported in modern enterprise environments. However, if legacy systems running these versions are still in use—common in some industrial control systems, critical infrastructure, or specialized environments—the risk is that sensitive information could be exposed if an attacker gains physical access to the machine or its storage media. This could lead to confidentiality breaches, potentially exposing user credentials or sensitive operational data. The vulnerability does not allow remote exploitation and does not affect system integrity or availability, limiting its impact to confidentiality concerns. Nonetheless, in environments where data confidentiality is critical, such as government agencies, financial institutions, or healthcare providers, even low-severity data leakage risks must be managed carefully. The lack of patch availability means organizations must rely on compensating controls rather than software fixes.

Since no patches are available for this vulnerability, European organizations should implement compensating controls to mitigate the risk. These include: 1) Physically securing legacy systems to prevent unauthorized physical access, including locked server rooms and controlled access to hardware. 2) Encrypting the entire disk or at least the page file partition using full disk encryption technologies to protect data at rest, ensuring that residual data in the page file cannot be easily recovered. 3) Implementing strict decommissioning and disposal procedures for legacy hardware, including secure wiping or destruction of storage media before disposal or reuse. 4) Where possible, upgrading legacy systems to supported operating systems that properly clear page files or use memory encryption features. 5) Employing endpoint security solutions that monitor and restrict access to sensitive data and system files. 6) Using system shutdown scripts or third-party tools that can securely clear or overwrite the page file during shutdown or startup, if compatible with legacy systems. These measures reduce the risk of sensitive data exposure due to page file remnants.