CVE-2003-0653 in NetBSD
Summary
by MITRE
The OSI networking kernel (sys/netiso) in NetBSD 1.6.1 and earlier does not use a BSD-required "PKTHDR" mbuf when sending certain error responses to the sender of an OSI packet, which allows remote attackers to cause a denial of service (kernel panic or crash) via certain OSI packets.
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Analysis
by VulDB Data Team • 10/08/2018
The vulnerability described in CVE-2003-0653 represents a critical flaw in the Open Systems Interconnection (OSI) networking implementation within NetBSD operating systems version 1.6.1 and earlier. This issue resides within the sys/netiso subsystem which handles OSI protocol processing, specifically affecting how the kernel manages memory buffers during error response generation. The flaw stems from the kernel's failure to properly initialize memory management buffers when processing certain error conditions, creating a fundamental violation of the operating system's memory management protocols.
The technical root cause of this vulnerability lies in the improper handling of mbuf structures, which are fundamental data structures used by BSD-based operating systems to manage network packet data. According to the Berkeley Software Distribution (BSD) memory management requirements, all packet headers must be properly initialized with PKTHDR structures before being processed. However, in the affected NetBSD versions, when the OSI kernel encounters certain malformed or unexpected OSI packets, it generates error responses without properly setting up the required PKTHDR mbuf structure. This omission creates a scenario where kernel memory management routines attempt to access uninitialized or improperly structured memory regions, leading to unpredictable behavior.
The operational impact of this vulnerability manifests as a complete denial of service condition that can result in kernel panics or system crashes. Remote attackers can exploit this weakness by crafting specially formatted OSI packets that trigger the faulty error handling path within the kernel. When the vulnerable system processes these packets, the improper memory buffer handling causes the kernel to crash, effectively rendering the affected system unavailable to legitimate users. This type of attack directly impacts system availability and can be particularly devastating in network infrastructure devices or servers that rely on stable network connectivity.
From a cybersecurity perspective, this vulnerability maps to CWE-121, which describes "Stack-based Buffer Overflow" and aligns with ATT&CK technique T1499.1, "Network Denial of Service" as it enables remote attackers to cause system crashes through network traffic. The attack vector requires only network access to the affected system and does not require authentication or special privileges, making it particularly dangerous in environments where systems are exposed to untrusted network traffic. The vulnerability also demonstrates poor adherence to memory safety practices and proper kernel programming standards that are essential for maintaining system stability and security in operating system kernels.
The recommended mitigations for this vulnerability include immediate upgrade to NetBSD versions 1.6.2 or later, which contain the necessary patches to properly initialize mbuf structures during error response generation. System administrators should also implement network segmentation and access controls to limit exposure to untrusted networks, while monitoring for unusual network traffic patterns that might indicate exploitation attempts. Additionally, organizations should conduct regular security assessments of their network infrastructure to identify and remediate similar memory management vulnerabilities that could exist in other kernel components or third-party network implementations.