CVE-2001-0284 in OpenBSD
Summary
by MITRE
Buffer overflow in IPSEC authentication mechanism for OpenBSD 2.8 and earlier allows remote attackers to cause a denial of service and possibly execute arbitrary commands via a malformed Authentication header (AH) IPv4 option.
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Analysis
by VulDB Data Team • 05/29/2018
The vulnerability described in CVE-2001-0284 represents a critical buffer overflow condition within the IPSEC authentication mechanism of OpenBSD versions 2.8 and earlier systems. This flaw exists within the handling of Authentication Header (AH) IPv4 options, specifically when processing malformed authentication data. The vulnerability stems from inadequate input validation and bounds checking within the kernel-level IPSEC implementation, creating a scenario where maliciously crafted packets can trigger memory corruption. The affected systems process these malformed AH options without proper sanitization, leading to potential exploitation of the buffer overflow condition.
The technical implementation of this vulnerability involves the IPSEC protocol's authentication header processing logic where the system fails to properly validate the length and content of incoming AH options. When an attacker crafts a packet with a malformed AH header containing oversized or malformed data, the kernel's processing routine attempts to copy this data into a fixed-size buffer without adequate bounds checking. This classic buffer overflow condition occurs because the system assumes the incoming data conforms to expected parameters, failing to account for maliciously constructed inputs that exceed allocated buffer boundaries. The vulnerability operates at the network layer where IPSEC packets are processed, making it particularly dangerous as it can be triggered through standard network traffic without requiring special privileges or authentication.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution on affected systems. When the buffer overflow occurs during AH header processing, it can corrupt adjacent memory locations and potentially overwrite critical system structures or return addresses. This memory corruption can lead to system crashes, resulting in denial of service, or in more severe cases, allow attackers to inject and execute arbitrary code with the privileges of the IPSEC processing daemon. The vulnerability affects systems running OpenBSD 2.8 and earlier versions, which were widely deployed in network security applications where IPSEC was commonly used for secure communications. The attack surface includes any system that accepts IPSEC traffic and processes AH headers, making it particularly dangerous for network infrastructure devices and security appliances.
Mitigation strategies for this vulnerability require immediate system updates to newer OpenBSD versions where the buffer overflow has been addressed through proper bounds checking and input validation. System administrators should implement network segmentation and access controls to limit exposure to untrusted networks, while also monitoring for suspicious traffic patterns that might indicate exploitation attempts. The implementation of intrusion detection systems capable of identifying malformed AH headers can provide early warning of potential attacks. Additionally, organizations should consider disabling IPSEC functionality on systems where it is not strictly required, and implement proper network monitoring to detect unusual traffic patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how network protocol implementations can create security risks when proper input validation is omitted. The attack vector falls under the ATT&CK technique of initial access through network service exploitation, specifically targeting the network infrastructure layer where IPSEC is implemented.