CVE-2000-0440 in FreeBSD
Summary
by MITRE
NetBSD 1.4.2 and earlier allows remote attackers to cause a denial of service by sending a packet with an unaligned IP timestamp option.
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Analysis
by VulDB Data Team • 06/22/2024
The vulnerability identified as CVE-2000-0440 represents a critical denial of service weakness in NetBSD operating systems version 1.4.2 and earlier. This flaw specifically targets the network stack's handling of IP timestamp options within incoming packets, creating a condition where malformed network traffic can trigger system instability. The issue stems from insufficient validation mechanisms within the kernel's IP processing routines, which fail to properly handle unaligned data structures in network protocol options.
The technical exploitation of this vulnerability occurs when a remote attacker crafts and sends network packets containing IP timestamp options with improper alignment. The NetBSD kernel's IP processing code does not adequately validate the alignment of these timestamp fields, causing the system to attempt to process misaligned data structures. This misalignment leads to memory access violations or unexpected behavior within the kernel's network subsystem, ultimately resulting in system instability and potential complete system crash or reboot. The vulnerability operates at the network protocol level, specifically affecting the Internet Protocol implementation within the operating system's kernel space.
From an operational perspective, this vulnerability presents significant risk to network infrastructure systems running affected NetBSD versions. Attackers can exploit this weakness with minimal resources to disrupt network services, making it particularly dangerous for servers, routers, and network appliances that rely on NetBSD. The denial of service impact can be sustained through repeated attacks, potentially causing prolonged service disruption. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation in kernel space operations. The attack vector requires only network connectivity to the target system, making it easily exploitable from remote locations.
The mitigation strategies for CVE-2000-0440 primarily involve upgrading to NetBSD versions that contain the necessary patches addressing the alignment handling issue. System administrators should prioritize applying security updates from NetBSD releases subsequent to 1.4.2, which include proper validation of IP timestamp options. Network administrators can implement temporary workarounds such as disabling IP timestamp processing at the network level or filtering packets containing malformed timestamp options. From an ATT&CK framework perspective, this vulnerability maps to the T1498 technique for network denial of service, specifically targeting the network infrastructure component. Organizations should also consider implementing intrusion detection systems to monitor for suspicious packet patterns that may indicate exploitation attempts. The vulnerability demonstrates how low-level kernel implementation flaws can create significant security risks, emphasizing the importance of proper memory alignment handling and input validation in system kernel code.