CVE-2000-0729 in FreeBSD
Summary
by MITRE
FreeBSD 5.x, 4.x, and 3.x allows local users to cause a denial of service by executing a program with a malformed ELF image header.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/26/2019
The vulnerability described in CVE-2000-0729 represents a critical denial of service flaw affecting multiple versions of the FreeBSD operating system including versions 3.x, 4.x, and 5.x. This issue stems from insufficient validation of ELF (Executable and Linkable Format) image headers during program execution, creating a pathway for malicious local users to disrupt system operations. The vulnerability is classified under CWE-122 as a buffer overflow condition that occurs when the system attempts to process malformed data structures without proper bounds checking. From an operational perspective, this weakness allows an attacker with local access to craft specially designed ELF binaries that, when executed, trigger system instability and resource exhaustion, effectively rendering the affected system unavailable to legitimate users.
The technical mechanism behind this vulnerability involves the FreeBSD kernel's ELF loader failing to properly validate the structure of ELF headers before attempting to load and execute programs. When a malformed ELF image is encountered, the system's parsing routines may encounter unexpected values or corrupted data structures that cause the kernel to either crash or enter an unstable state. This flaw specifically targets the program loading mechanism and operates at the kernel level, making it particularly dangerous as it can potentially lead to complete system hangs or reboots. The vulnerability manifests when the kernel's ELF parser encounters header fields that exceed expected bounds or contain invalid values, causing memory access violations or infinite loops in the parsing logic.
The operational impact of CVE-2000-0729 extends beyond simple system disruption to encompass broader security implications for FreeBSD systems in production environments. Local attackers who can execute code on the target system gain the ability to systematically deny service to other users and system processes, potentially causing cascading failures in network services or applications that depend on stable system operation. From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, though in this case the attack vector is local rather than network-based. The vulnerability also demonstrates characteristics of privilege escalation pathways where local users can leverage system-level flaws to cause widespread disruption. Organizations running affected FreeBSD versions face significant risk of service interruption and potential data loss if this vulnerability is exploited in environments where local access is possible.
Mitigation strategies for CVE-2000-0729 primarily focus on immediate system updates and patches provided by FreeBSD developers. The most effective remediation involves upgrading to FreeBSD versions that contain fixes for the ELF header validation logic, typically found in patched releases following the vulnerability disclosure. System administrators should also implement monitoring solutions to detect unusual program execution patterns that might indicate exploitation attempts. Additional defensive measures include restricting local user privileges where possible, implementing proper access controls, and conducting regular security audits of system binaries to identify potentially malicious executables. The vulnerability serves as a reminder of the importance of robust input validation in kernel-level code and demonstrates how seemingly minor parsing flaws can result in significant system stability issues. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across their FreeBSD infrastructure.