CVE-1999-0624 refers to the presence of the rstat/rstatd service running on a system. The rstat (remote statistics) service is a legacy UNIX daemon that provides system performance and status information remotely. It is an older service that predates modern monitoring tools and was designed to allow remote querying of system statistics such as CPU usage, memory usage, and disk activity. The vulnerability itself is not due to a software flaw or exploitable bug but rather the mere presence and exposure of the rstatd service. Since rstatd operates without authentication and transmits data in cleartext, it can be leveraged by attackers to gather sensitive system information remotely. This reconnaissance data can aid attackers in profiling systems for further targeted attacks. The CVSS vector indicates no direct impact on confidentiality, integrity, or availability (C:N/I:N/A:N), and no authentication is required (Au:N), with network attack vector (AV:N) and low attack complexity (AC:L). However, the service is considered obsolete and insecure by modern standards. There is no patch available because the service is deprecated, and best practice is to disable it entirely. The risk arises from information disclosure that can facilitate further exploitation rather than direct compromise. Modern systems typically do not run rstatd, but legacy UNIX or BSD systems might still have it enabled, especially in older infrastructure or embedded devices. The service's presence can be detected via network scanning, and its removal or disabling is recommended to reduce attack surface.

For European organizations, the impact of having the rstat/rstatd service running is primarily related to information disclosure. Attackers can remotely query system performance metrics without authentication, which can reveal details about system load, uptime, and resource usage. While this does not directly compromise system confidentiality, integrity, or availability, it provides valuable reconnaissance data that can be used to plan more sophisticated attacks such as targeted exploitation or denial of service. In critical infrastructure sectors or organizations with legacy UNIX systems, this could increase the risk profile. Additionally, compliance with modern security standards (e.g., GDPR, NIS Directive) may be affected if legacy services expose unnecessary information. Given the service is obsolete, its presence also indicates potentially outdated system management practices, which could correlate with other vulnerabilities. However, the direct impact is low since no direct exploitation or remote code execution is associated with this service alone.

The primary mitigation is to disable the rstat/rstatd service entirely on all systems where it is running. Since no patch is available, removing or stopping the service eliminates the exposure. Network administrators should audit their UNIX and BSD systems to identify any running instances of rstatd. Firewalls should block incoming traffic on the ports used by rstatd (typically UDP port 111 for portmapper and UDP port 512 for rstatd) from untrusted networks. If monitoring is required, organizations should migrate to modern, secure monitoring solutions that support encrypted and authenticated communication, such as SNMPv3 or dedicated monitoring agents. Regular vulnerability scanning and network reconnaissance should be performed to detect legacy services. Additionally, organizations should review and update their system inventory and decommission outdated systems that rely on legacy services. Training and awareness for system administrators regarding legacy service risks are also recommended.