CVE-2000-0489 in FreeBSD
Summary
by MITRE
FreeBSD, NetBSD, and OpenBSD allow an attacker to cause a denial of service by creating a large number of socket pairs using the socketpair function, setting a large buffer size via setsockopt, then writing large buffers.
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Analysis
by VulDB Data Team • 06/22/2024
This vulnerability affects multiple open source operating systems including FreeBSD, NetBSD, and OpenBSD, where an attacker can exploit a flaw in the socketpair system call implementation to trigger a denial of service condition. The vulnerability stems from insufficient resource management when handling socket pairs with large buffer sizes, allowing malicious actors to exhaust system resources through controlled allocation patterns. The attack vector specifically targets the socketpair function which creates bidirectional sockets for inter-process communication, combined with aggressive buffer size configuration through setsockopt calls. When combined with large buffer writes, this creates a scenario where system memory resources become rapidly depleted, leading to system instability and potential service disruption.
The technical flaw manifests in the kernel's handling of socket buffer allocation and management during socketpair operations. When an attacker creates multiple socket pairs with large buffer sizes and subsequently writes substantial data to these sockets, the kernel's memory management subsystem becomes overwhelmed with buffer allocations. This particular vulnerability operates at the kernel level and represents a classic resource exhaustion attack pattern that falls under CWE-400, which catalogs improper resource management issues. The flaw allows for unbounded memory allocation through legitimate system calls, creating a path for attackers to consume system resources without proper bounds checking or resource limits enforcement.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire system stability. Systems running affected versions of the operating systems become vulnerable to resource exhaustion attacks that can be executed with minimal privileges, making them particularly dangerous in multi-user environments. The attack can be executed remotely or locally, depending on system configuration, and requires no special privileges beyond basic user access. This creates a significant risk for servers and network services that rely on socketpair functionality for inter-process communication, as attackers can systematically consume memory resources until system performance degrades or crashes occur. The vulnerability particularly affects systems handling high volumes of concurrent connections or processes that utilize socketpair operations.
Mitigation strategies for this vulnerability focus on implementing proper resource limits and kernel parameter tuning to prevent unbounded memory allocation. System administrators should configure appropriate limits on socket buffer sizes and implement connection rate limiting to prevent abuse of socketpair functionality. The recommended approach includes adjusting kernel parameters such as net.core.wmem_max and net.core.rmem_max to enforce reasonable buffer size limits, along with implementing process and memory accounting mechanisms to detect and prevent resource exhaustion. Additionally, upgrading to patched versions of the affected operating systems represents the most effective long-term solution, as these updates typically include proper bounds checking and resource management improvements. Organizations should also consider implementing intrusion detection systems that can monitor for unusual socketpair activity patterns and establish proper network segmentation to limit the impact of successful attacks. This vulnerability demonstrates the importance of proper resource management in kernel-level system calls and aligns with ATT&CK technique T1499 which covers resource exhaustion attacks targeting system availability.