CVE-2000-0525 in OpenSSH
Summary
by MITRE
OpenSSH does not properly drop privileges when the UseLogin option is enabled, which allows local users to execute arbitrary commands by providing the command to the ssh daemon.
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Analysis
by VulDB Data Team • 10/14/2025
The vulnerability identified as CVE-2000-0525 represents a critical privilege escalation flaw within the OpenSSH implementation that directly impacts system security through improper privilege handling mechanisms. This issue specifically manifests when the UseLogin option is enabled in the SSH daemon configuration, creating a dangerous condition where local users can bypass normal security controls to execute arbitrary commands with elevated privileges. The vulnerability stems from the ssh daemon's failure to properly relinquish elevated privileges after authentication, allowing malicious actors to maintain access to system resources beyond what should be permitted.
The technical flaw resides in the privilege dropping mechanism within OpenSSH's authentication process, where the daemon fails to correctly transition from root privileges to the target user account when UseLogin is enabled. This misconfiguration creates a window where commands provided during the SSH session can be executed with the privileges of the user account being accessed, rather than the privileges of the user who initiated the connection. The vulnerability is particularly dangerous because it operates at the core of SSH authentication, where the system's security model is fundamentally compromised. According to CWE classification, this represents a privilege escalation vulnerability categorized under CWE-276, which deals with incorrect privileges assigned to resources, and specifically aligns with CWE-782 which addresses improper privilege management in network services.
The operational impact of CVE-2000-0525 extends beyond simple local privilege escalation to potentially enable full system compromise, as local users who can establish SSH connections can leverage this flaw to execute malicious commands with root privileges. Attackers can exploit this vulnerability to gain unauthorized access to system resources, modify critical files, install backdoors, or perform other malicious activities that would otherwise be restricted to legitimate administrators. The vulnerability affects systems running OpenSSH versions prior to 2.9.9 and 3.0.2, making it particularly relevant to older deployments that may not have received timely security updates. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Local Privilege Escalation) and T1566 (Phishing) as attackers can potentially use this to establish persistent access after initial compromise.
Mitigation strategies for CVE-2000-0525 require immediate action to address the root cause through proper system configuration and software updates. The most effective immediate solution involves disabling the UseLogin option in the SSH daemon configuration file, typically located at /etc/ssh/sshd_config, where the line UseLogin yes should be changed to UseLogin no or completely removed. System administrators should also ensure that all OpenSSH installations are updated to versions that have patched this vulnerability, with recommended versions being 2.9.9 or 3.0.2 and later. Additional protective measures include implementing proper access controls, monitoring SSH connection logs for suspicious activity, and ensuring that privilege escalation mechanisms are properly configured throughout the system. The vulnerability highlights the critical importance of proper privilege management in network services and demonstrates how seemingly minor configuration options can create significant security weaknesses that can be exploited by malicious actors to gain unauthorized access to system resources and potentially compromise entire networks.