CVE-1999-0185 in Solaris
Summary
by MITRE
In SunOS or Solaris, a remote user could connect from an FTP server's data port to an rlogin server on a host that trusts the FTP server, allowing remote command execution.
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Analysis
by VulDB Data Team • 04/17/2026
This vulnerability exists in SunOS and Solaris operating systems where the ftp daemon lacks proper security controls when establishing data connections. The flaw allows a remote attacker to exploit the trust relationship between the ftp server and other services on the network, specifically targeting rlogin servers that may trust the ftp server's connections. The vulnerability stems from the absence of proper authentication checks and connection validation mechanisms within the ftp daemon's data transfer functionality. When an ftp client connects to an ftp server, the server may establish data connections to other hosts using the same credentials or trust relationships, creating an attack vector that bypasses normal security boundaries. This represents a classic case of improper access control where the ftp service fails to validate the destination of data connections, effectively allowing arbitrary connections to trusted services. The vulnerability is classified under cwe-284 which deals with improper access control, and aligns with attack techniques described in the attack pattern taxonomy for privilege escalation through service trust relationships. The exploitation process involves the attacker initiating an ftp session and then manipulating the data connection to redirect traffic to an rlogin server that trusts the ftp server's identity, thereby gaining unauthorized access to the target system. This vulnerability demonstrates the critical importance of proper network segmentation and service isolation, as it allows attackers to leverage one service to compromise another through trust relationships. The impact of this vulnerability is severe as it can lead to complete system compromise, allowing attackers to execute arbitrary commands with the privileges of the ftp daemon user. The attack can be executed remotely without requiring authentication to the ftp service itself, making it particularly dangerous in network environments where ftp services are exposed to untrusted networks. Security practitioners should recognize this as a fundamental flaw in service trust management and implement proper network access controls to prevent such lateral movement attacks. The vulnerability highlights the need for robust credential management and the principle of least privilege, where services should not be granted unnecessary trust relationships that could be exploited by attackers. Mitigation strategies should include disabling unnecessary services, implementing proper firewall rules to restrict access between ftp and rlogin services, and ensuring that trust relationships are carefully managed and validated. Network segmentation and the use of network access control lists can help prevent unauthorized communication between services that should not trust each other. Additionally, administrators should consider disabling rlogin services entirely in favor of more secure alternatives like ssh. The vulnerability also underscores the importance of proper service configuration and the need for regular security audits to identify and remediate trust relationship issues that could be exploited by attackers. This particular vulnerability represents an early example of how trust relationships in network services could be abused to escalate privileges and achieve unauthorized access to systems. The attack pattern aligns with techniques described in the attack tree methodology for privilege escalation through service trust abuse, where attackers exploit the implicit trust relationships that exist between network services. Modern security frameworks emphasize the need for zero trust architectures where no service or user is trusted by default, regardless of their location within the network. This vulnerability serves as a historical example of why network segmentation and explicit access controls are essential components of modern cybersecurity defenses. The flaw demonstrates how seemingly innocuous service interactions can create significant security risks when proper access controls are not implemented. Organizations should implement comprehensive network monitoring to detect unusual service communication patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date system patches and security configurations, as this issue was resolved through proper implementation of access controls and connection validation mechanisms in later system versions. Proper incident response procedures should include immediate isolation of affected systems and thorough network forensics to identify any potential compromise from such attacks.