CVE-1999-0845 in UnixWare
Summary
by MITRE
Buffer overflow in SCO su program allows local users to gain root access via a long username.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/24/2024
The vulnerability described in CVE-1999-0845 represents a classic buffer overflow flaw within the SCO Unix operating system's su program, which serves as the standard utility for switching user privileges. This issue specifically affects the authentication mechanism of the system, where the su command fails to properly validate input length when processing usernames. The flaw exists in the way the program handles user input during the privilege escalation process, creating an exploitable condition that can be leveraged by local attackers to bypass normal security controls. The vulnerability is particularly concerning because it allows a local user to escalate their privileges to root level without requiring authentication credentials, effectively undermining the fundamental security model of the operating system.
The technical implementation of this buffer overflow stems from inadequate bounds checking within the su program's username processing routine. When a user attempts to switch to another account using su, the program allocates a fixed-size buffer to store the username argument. However, the program does not validate whether the input exceeds the allocated buffer size, allowing an attacker to provide an excessively long username string. This overflow can overwrite adjacent memory locations, including the return address on the stack, enabling arbitrary code execution. According to CWE classification, this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write operations. The attack vector is particularly effective because it requires no network connectivity and can be executed locally, making it difficult to detect through traditional network monitoring systems.
The operational impact of CVE-1999-0845 extends beyond simple privilege escalation, as it fundamentally compromises system integrity and confidentiality. Once a local user successfully exploits this vulnerability, they gain complete root access to the system, enabling them to modify critical system files, install backdoors, steal sensitive data, or disrupt system operations. This local privilege escalation vulnerability represents a significant threat to system security, as it allows attackers to bypass authentication mechanisms entirely and operate with the highest possible system privileges. The vulnerability affects all versions of SCO Unix that contain the flawed su program implementation, making it a widespread concern for organizations running these legacy systems. From an ATT&CK framework perspective, this vulnerability aligns with techniques categorized under privilege escalation and execution, specifically mapping to T1068 for local privilege escalation and T1059 for command and scripting interpreter usage.
Mitigation strategies for this vulnerability require immediate implementation of system updates and patches provided by SCO, as well as implementing additional security controls to limit the attack surface. Organizations should ensure that all systems running affected versions of SCO Unix are updated with the latest security patches that address the buffer overflow condition in the su program. Additionally, system administrators should implement proper access controls, including limiting the number of users with access to the su command and monitoring for unusual privilege escalation attempts. The vulnerability highlights the importance of input validation and bounds checking in system utilities, particularly those handling authentication and privilege management functions. Security monitoring should include detection of unusually long command line arguments passed to su commands, and system hardening measures should be implemented to prevent exploitation of such buffer overflow conditions. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other system utilities and ensure that proper defensive coding practices are followed throughout the system.