CVE-1999-1119 in AIX
Summary
by MITRE
FTP installation script anon.ftp in AIX insecurely configures anonymous FTP, which allows remote attackers to execute arbitrary commands.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-1119 represents a critical security flaw in the AIX operating system's FTP installation process that enables remote command execution through insecure anonymous FTP configuration. This issue specifically affects the anon.ftp installation script used during AIX FTP server setup, where the script fails to properly secure anonymous FTP access by creating overly permissive user accounts and directory permissions. The vulnerability stems from inadequate privilege separation and improper access control mechanisms during the initial system configuration phase, creating a persistent backdoor that remains exploitable long after the initial installation.
The technical flaw manifests in how the installation script handles anonymous FTP user creation and directory permissions within the AIX system. When the anon.ftp script executes, it establishes an anonymous FTP user account with excessive privileges and creates directory structures that allow arbitrary file operations. This misconfiguration enables attackers to upload malicious files, execute commands with elevated privileges, and potentially gain full system control. The vulnerability is particularly dangerous because it operates at the system installation level, meaning that any AIX system running the vulnerable FTP service is immediately compromised upon installation. The flaw directly relates to CWE-264, which covers permissions, privileges, and access controls, and more specifically addresses CWE-78, which deals with OS command injection vulnerabilities.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it provides attackers with complete system compromise capabilities. Once exploited, an attacker can execute arbitrary commands with root privileges, potentially leading to complete system takeover, data exfiltration, and persistent access to network resources. The vulnerability affects any AIX system that has installed FTP services using the vulnerable installation script, creating a widespread security risk across enterprise networks where AIX systems are deployed. Organizations running AIX servers without proper patching or mitigation measures face significant exposure to this vulnerability, as it essentially creates an unauthenticated backdoor that can be exploited by anyone with network access to the FTP service.
Mitigation strategies for this vulnerability require immediate action to address the root cause through proper system hardening and patch management. Organizations must first identify all AIX systems running vulnerable FTP configurations and manually correct the anonymous FTP user permissions and directory access controls. The recommended approach involves disabling anonymous FTP access entirely when it is not required, or implementing strict access controls that limit anonymous users to read-only operations only. System administrators should also implement network segmentation to restrict FTP access to trusted networks and deploy intrusion detection systems to monitor for suspicious FTP activity. Additionally, organizations should conduct comprehensive security audits to identify any other instances of insecure script configurations that might create similar vulnerabilities. This vulnerability demonstrates the critical importance of secure system configuration practices and highlights the need for regular security assessments of system installation processes, aligning with ATT&CK technique T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation. The remediation process should include implementing proper access control lists, regular security patching, and maintaining up-to-date system configuration baselines that prevent similar insecure configurations from being introduced during system deployment.