CVE-2000-0752 in FreeBSD
Summary
by MITRE
Buffer overflows in brouted in FreeBSD and possibly other OSes allows local users to gain root privileges via long command line arguments.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability identified as CVE-2000-0752 represents a critical buffer overflow flaw within the brouted daemon component of FreeBSD operating systems and potentially other Unix-like systems. This issue resides in the handling of command line arguments within the brouted service, which is responsible for routing packets between network interfaces. The flaw manifests when the daemon processes excessively long command line parameters, causing memory corruption that can be exploited by local attackers to escalate privileges to root level access. The vulnerability specifically targets the brouted service which operates as a routing daemon, making it a significant concern for network administrators managing FreeBSD systems. The buffer overflow occurs in the argument parsing logic where insufficient bounds checking allows an attacker to overwrite adjacent memory locations, potentially corrupting the program's execution flow. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, where the attacker can manipulate the program's control flow by overwriting return addresses and other critical stack data. The attack vector requires local system access since the brouted daemon typically runs with elevated privileges, making it an attractive target for privilege escalation attacks.
The technical exploitation of this vulnerability relies on the attacker's ability to pass maliciously crafted command line arguments that exceed the allocated buffer size. When the brouted daemon processes these arguments, the overflow corrupts the stack memory, potentially allowing an attacker to overwrite the return address of the main function or other critical variables. This memory corruption can be leveraged to execute arbitrary code with root privileges, effectively bypassing normal access controls. The vulnerability's impact is particularly severe because the brouted service usually operates with root privileges, meaning successful exploitation directly results in full system compromise. The flaw demonstrates a classic stack-based buffer overflow pattern where the program fails to validate the length of input arguments before copying them into fixed-size buffers. The attacker must carefully construct the command line arguments to ensure proper alignment of the overflow to overwrite the necessary memory locations for code execution. This vulnerability aligns with ATT&CK technique T1068 which describes the use of local privilege escalation techniques through exploitation of software vulnerabilities. The attack requires the attacker to have local access to the system, typically through a user account, but the privilege escalation to root level access makes the impact substantial.
The operational impact of CVE-2000-0752 extends beyond simple privilege escalation, as it represents a fundamental security weakness in the FreeBSD networking stack that could be exploited for broader system compromise. Network administrators must consider that systems running brouted services are at risk from local attackers who may have minimal access but can leverage this vulnerability to gain complete control over the affected systems. The vulnerability affects not only FreeBSD systems but potentially other operating systems that implement similar routing daemon functionality, making it a widespread concern for network infrastructure administrators. Organizations using FreeBSD or similar systems must evaluate their exposure to this vulnerability through proper vulnerability scanning and assessment procedures. The impact is particularly concerning for systems that rely on brouted for network routing functions, as these systems may be targeted by attackers seeking to compromise network infrastructure. The vulnerability also highlights the importance of proper input validation and bounds checking in system services, as the lack of these security measures can lead to complete system compromise. System administrators should implement immediate mitigations including updating to patched versions of FreeBSD, disabling unnecessary routing services, and monitoring for suspicious local activity. The vulnerability demonstrates how seemingly minor flaws in system services can have severe consequences, emphasizing the need for comprehensive security testing and code review processes in operating system components.
Mitigation strategies for CVE-2000-0752 should focus on both immediate remediation and long-term security hardening measures. The primary recommendation involves upgrading to patched versions of FreeBSD that address the buffer overflow vulnerability in brouted, as this directly resolves the underlying flaw. System administrators should also consider disabling the brouted service if it is not essential for network operations, reducing the attack surface for potential exploitation. Additionally, implementing proper input validation and bounds checking in system services can prevent similar vulnerabilities from occurring in the future. Security monitoring should include detection of unusual command line argument patterns that might indicate exploitation attempts, and network segmentation can help limit the impact if an attacker successfully exploits the vulnerability. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date system software and implementing comprehensive security practices throughout the system lifecycle. Organizations should also consider implementing additional security controls such as mandatory access controls, privilege separation, and regular security assessments to prevent similar vulnerabilities from being exploited in other system components. The incident underscores the necessity of proper software development practices including secure coding guidelines and thorough security testing to prevent buffer overflow vulnerabilities from reaching production environments.