CVE-2000-0998 in FreeBSD
Summary
by MITRE
Format string vulnerability in top program allows local attackers to gain root privileges via the "kill" or "renice" function.
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Analysis
by VulDB Data Team • 09/12/2024
The vulnerability identified as CVE-2000-0998 represents a critical format string flaw within the top system monitoring program that operates with elevated privileges. This issue specifically affects the kill and renice functions, which are designed to manage process priorities and terminate processes. The top program, commonly used for system monitoring and process management, runs with root privileges to access comprehensive system information, creating a significant attack surface when combined with format string vulnerabilities.
The technical flaw stems from improper input validation within the format string handling mechanisms of the top program's kill and renice functions. When these functions process user-provided arguments, they fail to properly sanitize input before using it in printf-style formatting operations. This allows local attackers to craft malicious input strings containing format specifiers that can trigger undefined behavior. The vulnerability occurs because the program directly uses user-supplied data as format strings without proper validation or escaping, creating opportunities for attackers to manipulate memory contents and execute arbitrary code.
The operational impact of this vulnerability is severe as it enables local privilege escalation from regular user accounts to root privileges. Attackers can exploit this flaw by providing specially crafted arguments to the kill or renice commands within the top program, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates within a program that typically runs with elevated privileges, and the attack vector requires only local access rather than network exposure. This makes exploitation straightforward and potentially undetectable within system monitoring contexts.
Security implications extend beyond immediate privilege escalation, as this vulnerability can be leveraged to execute arbitrary code with root privileges, potentially allowing attackers to modify system files, install backdoors, or exfiltrate sensitive information. The flaw aligns with CWE-134 which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1068 which covers privilege escalation through local exploitation of software vulnerabilities, and T1059 which encompasses command and scripting interpreters for code execution.
Mitigation strategies should prioritize immediate patching of affected top program versions, as this vulnerability was addressed through proper input validation and format string handling. System administrators should implement the latest security updates and ensure that system monitoring tools are regularly maintained. Additionally, privilege separation techniques should be employed to reduce the attack surface, and monitoring should be implemented to detect anomalous usage patterns of system monitoring tools. The vulnerability demonstrates the critical importance of proper input validation and the principle of least privilege in security design, particularly for programs operating with elevated system permissions.