CVE-1999-0030 in IRIX
Summary
by MITRE
root privileges via buffer overflow in xlock command on sgi irix systems.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0030 represents a critical buffer overflow flaw in the xlock command on SGI IRIX systems that allows local attackers to escalate privileges to root level. This issue specifically affects systems running the SGI IRIX operating system where the xlock utility contains a buffer overflow condition in its argument processing. The vulnerability stems from improper input validation within the xlock command implementation, which fails to properly bounds-check user-supplied arguments before copying them into fixed-size buffers. When an attacker provides carefully crafted input exceeding the allocated buffer space, the overflow corrupts adjacent memory regions including return addresses and control data structures. This memory corruption can be exploited to redirect program execution flow and ultimately gain root privileges on the affected system. The flaw is particularly dangerous because it allows privilege escalation from a regular user account to the highest system privileges, effectively providing complete system compromise.
The technical implementation of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack vector operates through the command line argument processing mechanism where the xlock utility fails to validate the length of input parameters before copying them into internal buffers. The SGI IRIX operating system architecture, combined with the specific implementation of the xlock utility, creates an environment where such buffer overflows can be reliably exploited to achieve privilege escalation. The vulnerability exists in the program's memory management practices where insufficient bounds checking allows attackers to overwrite critical program memory locations. This type of vulnerability falls under the ATT&CK technique T1068, which describes Exploitation for Privilege Escalation, specifically targeting local privilege escalation opportunities within the operating system.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration. Once an attacker successfully exploits this vulnerability, they gain unrestricted access to all system resources, including the ability to modify system files, create new user accounts, install malicious software, and access sensitive data. The attack requires local system access and execution privileges but does not need network connectivity, making it particularly concerning for systems where local access is possible. The vulnerability affects the integrity and confidentiality of the entire system, as root access provides complete control over all processes, files, and network connections. Organizations running SGI IRIX systems were particularly vulnerable to this attack, as the operating system's architecture and the specific implementation of xlock created predictable exploitation conditions that attackers could reliably reproduce.
Mitigation strategies for CVE-1999-0030 require immediate system updates and administrative actions to prevent exploitation. The primary solution involves applying vendor patches or upgrading to patched versions of the SGI IRIX operating system that address the buffer overflow condition in xlock. System administrators should also implement privilege separation measures, ensuring that the xlock utility runs with minimal necessary privileges and that input validation is strengthened throughout the system. Additional protective measures include disabling unnecessary local execution capabilities, implementing proper access controls, and monitoring system logs for suspicious activity related to privilege escalation attempts. Network segmentation and host-based intrusion detection systems can help identify exploitation attempts, while regular security audits should verify that all system components have been properly patched. The vulnerability highlights the importance of secure coding practices, particularly around input validation and memory management, and demonstrates how seemingly benign utilities can contain critical security flaws that affect system integrity and security posture.