CVE-1999-1324 in OpenVMS
Summary
by MITRE
VAXstations running Open VMS 5.3 through 5.5-2 with VMS DECwindows or MOTIF do not properly disable access to user accounts that exceed the break-in limit threshold for failed login attempts, which makes it easier for attackers to conduct brute force password guessing.
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Analysis
by VulDB Data Team • 04/20/2026
This vulnerability exists in DEC Open VMS operating systems version 5.3 through 5.5-2 running on VAXstation hardware with DECwindows or MOTIF interfaces. The flaw represents a critical security weakness in the system's authentication mechanism that directly violates fundamental security principles. The vulnerability stems from improper implementation of account lockout policies, where user accounts that exceed the configured break-in limit threshold for failed login attempts remain accessible to potential attackers. This design flaw creates an environment where malicious actors can exploit the system's failure to properly enforce account lockout mechanisms, enabling them to conduct systematic brute force password guessing attacks against legitimate user accounts. The vulnerability is particularly concerning because it affects a widely deployed operating system in enterprise environments where security is paramount. According to CWE classification, this represents a weakness in the authentication system where insufficient account lockout controls are implemented, making it easier for attackers to exploit the system through automated password guessing techniques. The operational impact of this vulnerability extends beyond simple credential theft, as it provides attackers with increased opportunities to escalate privileges and gain unauthorized access to sensitive system resources. The presence of DECwindows or MOTIF interfaces in affected systems compounds the risk since these graphical environments often provide additional attack surfaces for privilege escalation attempts.
The technical implementation flaw lies in the authentication subsystem's failure to properly enforce account lockout policies when maximum failed login attempts are exceeded. In properly configured systems, when a user account reaches its configured threshold for failed authentication attempts, the system should automatically lock the account and prevent further login attempts until manually unlocked by an administrator or until a predetermined timeout period expires. However, in the affected Open VMS versions, this critical security control mechanism fails to function correctly, leaving accounts accessible even after reaching their maximum failed attempt limits. This allows attackers to continue attempting to authenticate with various password combinations without facing the normal account lockout mechanisms that would typically slow down or prevent such automated attacks. The vulnerability operates at the operating system level within the authentication service, making it particularly difficult to detect and remediate without proper system updates or patches. From an attack perspective, this vulnerability aligns with ATT&CK technique T1110.003 which describes the use of credential stuffing and brute force attacks against authentication systems. The vulnerability's presence in DECwindows and MOTIF environments increases the attack surface since these interfaces often provide additional authentication pathways and may not properly inherit the same account lockout protections as command-line interfaces.
The implications of this vulnerability extend to enterprise security posture and compliance requirements, particularly in environments where access control and authentication mechanisms are critical for protecting sensitive data and system integrity. Organizations running affected systems are exposed to significant risk of unauthorized access, data breaches, and potential system compromise through automated credential guessing attacks. The vulnerability's persistence across multiple versions of Open VMS indicates a systemic design flaw that was not adequately addressed in the affected releases, suggesting that organizations should consider immediate remediation actions. The lack of proper account lockout enforcement creates an environment where attackers can systematically work through password dictionaries or rainbow tables against user accounts without encountering the normal security controls that would typically prevent such attacks. This vulnerability is particularly dangerous in multi-user environments where attackers can target multiple accounts simultaneously, potentially gaining access to privileged accounts with elevated system permissions. Security professionals should note that this vulnerability directly impacts the principle of least privilege and proper access control enforcement, which are fundamental requirements for maintaining system integrity and protecting against unauthorized access attempts. Organizations should implement immediate monitoring for failed authentication attempts and consider manual account lockout procedures as temporary mitigations while planning for proper system updates or patches.
Mitigation strategies for this vulnerability should focus on implementing compensating controls that address the missing account lockout functionality. System administrators should establish manual monitoring procedures for failed login attempts and implement immediate account lockout procedures when threshold limits are exceeded. Organizations should consider implementing additional authentication controls such as two-factor authentication or hardware security tokens to reduce the risk of credential compromise. The implementation of centralized logging and monitoring solutions can help detect suspicious authentication patterns and alert administrators to potential brute force attacks. Security policies should be updated to include specific procedures for handling account lockout situations and ensuring that manual account lockout mechanisms are properly enforced. Additionally, organizations should consider upgrading to patched versions of Open VMS where the account lockout functionality has been properly implemented and tested. The vulnerability serves as a reminder of the importance of proper authentication system design and the critical need for thorough security testing of access control mechanisms in operating system implementations. Regular security assessments should include verification of account lockout and failed authentication handling procedures to ensure that these critical security controls are properly functioning. Organizations should also review their overall authentication strategy and consider implementing additional layers of security controls to protect against the types of attacks that this vulnerability enables.