CVE-2000-0962 in OpenBSD
Summary
by MITRE
The IPSEC implementation in OpenBSD 2.7 does not properly handle empty AH/ESP packets, which allows remote attackers to cause a denial of service.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/28/2018
The vulnerability identified as CVE-2000-0962 represents a critical flaw in the IPSEC implementation of OpenBSD version 2.7, specifically affecting the Authentication Header (AH) and Encapsulating Security Payload (ESP) protocols. This issue stems from inadequate packet validation mechanisms within the kernel-level IPSEC processing code, creating a condition where malformed or empty packets can trigger unexpected behavior in the network security subsystem. The flaw manifests when the system receives empty AH or ESP packets that do not conform to standard protocol specifications, leading to potential system instability and service disruption.
The technical root cause of this vulnerability lies in the insufficient input validation and error handling within the IPSEC packet processing pipeline. When the OpenBSD kernel encounters empty AH or ESP packets, the processing routines fail to properly validate packet contents before attempting to parse or process them. This lack of proper boundary checking and input sanitization creates a condition where the system's memory management routines can be manipulated through crafted packet sequences, potentially leading to memory corruption or resource exhaustion. The vulnerability operates at the network protocol level, specifically targeting the IPSEC security framework that is fundamental to secure communications in the operating system.
From an operational impact perspective, this vulnerability presents a significant risk to systems running OpenBSD 2.7 with IPSEC enabled, as remote attackers can exploit this weakness to generate denial of service conditions without requiring authentication or special privileges. The attack vector is straightforward and can be executed over the network, making it particularly dangerous in environments where IPSEC is actively used for secure communications. The service disruption can range from temporary network connectivity issues to complete system crashes, depending on the specific implementation details and system configuration. This vulnerability directly affects the availability aspect of the CIA security triad, compromising the system's ability to provide continuous service to legitimate users.
The mitigation strategies for CVE-2000-0962 primarily focus on immediate system updates and configuration adjustments. The most effective solution involves upgrading to a newer version of OpenBSD that contains patches addressing the specific IPSEC packet handling issues, as the vulnerability was resolved in subsequent releases through improved input validation and error handling mechanisms. System administrators should also implement network-level filtering to drop suspicious IPSEC packets or configure firewalls to limit the exposure of systems running vulnerable IPSEC implementations. Additionally, monitoring network traffic for anomalous packet patterns and implementing intrusion detection systems can help identify potential exploitation attempts. This vulnerability aligns with CWE-129, which addresses improper input validation, and represents a classic example of how protocol implementation flaws can lead to denial of service conditions, similar to techniques documented in the ATT&CK framework under network denial of service tactics.
The broader implications of this vulnerability extend beyond simple service disruption, as it highlights the critical importance of robust input validation in security-critical kernel components. The flaw demonstrates how seemingly minor protocol handling issues can be exploited to create significant system instability, emphasizing the need for comprehensive security testing and code review processes. Organizations relying on IPSEC implementations must ensure they maintain current security patches and conduct regular vulnerability assessments to prevent similar issues from compromising their network infrastructure. The incident also underscores the necessity of following security best practices such as principle of least privilege and defense in depth, as systems with IPSEC enabled should have additional protective measures in place to mitigate the impact of such vulnerabilities.