CVE-1999-1253 in OpenServer
Summary
by MITRE
Vulnerability in a kernel error handling routine in SCO OpenServer 5.0.2 and earlier, and SCO Internet FastStart 1.0, allows local users to gain root privileges.
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Analysis
by VulDB Data Team • 04/16/2026
This vulnerability resides within the kernel error handling mechanisms of SCO OpenServer operating systems, specifically affecting versions 5.0.2 and earlier, as well as SCO Internet FastStart 1.0. The flaw manifests in how the system processes certain error conditions during kernel operations, creating a privilege escalation opportunity for local attackers who already possess user-level access to the system. The vulnerability represents a classic case of improper privilege management within kernel space, where error handling routines fail to properly validate or restrict access to critical system resources. This type of weakness falls under the CWE-264 category of "Permissions, Privileges, and Access Controls" and specifically relates to improper handling of kernel-level errors that can be exploited to elevate privileges from user to root level.
The technical exploitation of this vulnerability occurs when a local user triggers a specific error condition within the kernel error handling routine, allowing the attacker to manipulate system memory or execution flow to gain elevated privileges. The flaw typically involves a race condition or improper validation of user-supplied data within kernel contexts, enabling attackers to bypass normal access controls and execute arbitrary code with root privileges. This represents a critical security issue because it transforms a local user account into a root-level administrator, providing complete control over the system including the ability to modify or delete any files, install malicious software, and access all system resources. The vulnerability can be leveraged to establish persistent backdoors or to compromise the integrity of the entire system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security model of the affected operating systems. Once exploited, attackers can maintain persistent access to compromised systems, monitor network traffic, and potentially use the compromised system as a launching point for attacks against other networked systems. This vulnerability particularly affects enterprise environments where SCO OpenServer systems may be running legacy applications or critical business processes, making the potential damage substantial. The lack of proper kernel error handling validation creates an attack surface that can be exploited by both malicious insiders and external attackers who have gained initial access to the system through other means, as the vulnerability provides a reliable path to root access regardless of other security measures in place.
Mitigation strategies for this vulnerability include immediate application of vendor patches and updates specifically designed to address the kernel error handling flaw, along with comprehensive system hardening measures that reduce the attack surface. Organizations should implement strict access controls and monitor for unusual system behavior that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and demonstrates the importance of maintaining up-to-date system patches and implementing proper kernel security measures. System administrators should also consider implementing additional monitoring and logging mechanisms to detect potential exploitation attempts, as this type of vulnerability often leaves subtle traces in system logs that can aid in forensic analysis and incident response activities. Regular security assessments and vulnerability scanning should be conducted to identify systems running affected versions and ensure proper remediation has been implemented.