CVE-1999-0624 in Host
Summary
by MITRE
The rstat/rstatd service is running.
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Analysis
by VulDB Data Team • 10/25/2025
The rstat service represents a fundamental security vulnerability within Unix and Linux systems that has persisted for decades, primarily due to its inherent design flaws and lack of proper authentication mechanisms. This service operates on port 555 and provides system statistics information to remote clients without requiring any form of authentication or encryption. The vulnerability stems from the service's default configuration where it listens for connections from any host on the network, making it an attractive target for malicious actors seeking to gather system information for further exploitation. The service was originally designed for network monitoring and system administration purposes but has become a significant security risk due to its exposure and lack of access controls.
The technical flaw in the rstat/rstatd service lies in its complete absence of authentication and authorization checks. When the service is running, it accepts connections from any remote system and provides detailed system statistics including load averages, memory usage, process information, and network statistics without requiring credentials or verifying client identity. This design violates fundamental security principles and creates an information disclosure vulnerability that allows attackers to gather intelligence about the target system. The service operates using a simple protocol that transmits data in plain text, making it susceptible to interception and manipulation. According to the CWE database, this represents a classic example of CWE-200: Information Exposure, where sensitive system information is made available to unauthorized parties. The service also demonstrates characteristics of CWE-310: Cryptographic Issues, as it lacks any form of data encryption for transmitted information.
The operational impact of the rstat service vulnerability extends far beyond simple information disclosure, as it provides attackers with crucial intelligence for planning more sophisticated attacks. The gathered system statistics can reveal system load patterns, available memory, running processes, and network configuration details that significantly aid in crafting targeted exploits. Security professionals have documented how this information can be used to identify system vulnerabilities, determine optimal timing for attacks, and even assist in privilege escalation attempts. The service essentially provides a reconnaissance tool for attackers without requiring any special privileges or credentials, making it particularly dangerous in environments where it remains enabled by default. From an attacker's perspective, this service represents a low-hanging fruit that can provide substantial operational value with minimal effort, aligning with ATT&CK technique T1082: System Information Discovery, which focuses on gathering information about the target system. The service's exposure also violates the principle of least privilege, as it provides access to system information that should be restricted to authorized administrators only.
Mitigation strategies for the rstat/rstatd service vulnerability should begin with immediate service termination and configuration changes to prevent unauthorized access. The most effective approach involves disabling the service entirely, as it provides no legitimate security benefit in modern network environments. System administrators should verify that the service is not running by checking for processes such as rstatd or rstatd.exe and ensuring that the service is disabled in the system startup configuration. Network-level protections should include firewall rules that block incoming connections on port 555, preventing unauthorized access to the service. Additionally, regular security audits should be conducted to ensure that the service remains disabled and that no unauthorized systems have enabled it. The service should be completely removed from systems unless absolutely required for legacy applications, and even then, it should be configured with strict access controls and network segmentation. Organizations should also implement network monitoring to detect any attempts to access the service and establish incident response procedures for handling potential exploitation attempts. According to security best practices, the rstat service should never be enabled in production environments without proper network segmentation and access controls, as it fundamentally undermines the security posture of the system.