CVE-2004-0221 in OpenBSD
Summary
by MITRE
isakmpd in OpenBSD 3.4 and earlier allows remote attackers to cause a denial of service (crash) via an ISAKMP packet with a delete payload containing a large number of SPIs, which triggers an out-of-bounds read error, as demonstrated by the Striker ISAKMP Protocol Test Suite.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability identified as CVE-2004-0221 affects the isakmpd daemon in OpenBSD versions 3.4 and earlier, representing a critical denial of service flaw within the Internet Security Association and Key Management Protocol implementation. This vulnerability specifically targets the ISAKMP (Internet Security Association and Key Management Protocol) processing functionality that handles security associations and key management for IPsec implementations. The issue manifests when the isakmpd service receives a malformed ISAKMP packet containing a delete payload with an excessive number of Security Parameter Indexes. This particular flaw falls under the category of improper input validation and memory handling within cryptographic protocol implementations, making it a significant concern for network security infrastructure.
The technical exploitation of this vulnerability occurs through a precise manipulation of ISAKMP packet structures where an attacker crafts a delete payload that contains an inordinately large number of SPI entries. When the isakmpd daemon processes this malformed packet, it fails to properly validate the size of the SPI array within the delete payload, leading to an out-of-bounds memory read operation. This memory access violation causes the daemon to crash and terminate unexpectedly, resulting in a complete denial of service for the affected system's IPsec functionality. The vulnerability is particularly dangerous because it requires no authentication or privileged access to exploit, making it a significant threat in network environments where IPsec services are actively utilized.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise the entire security infrastructure of systems relying on OpenBSD's IPsec implementation. Network administrators and security professionals face the challenge of maintaining secure communications channels while dealing with the potential for unexpected service interruptions. The vulnerability demonstrates a fundamental flaw in input validation procedures within the ISAKMP processing code, where array bounds checking is insufficient to handle malformed data structures. This type of vulnerability is classified under CWE-129 as "Improper Validation of Array Index" and represents a classic example of how buffer overflows and out-of-bounds memory access can lead to system instability and denial of service conditions.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1499.004 for "Endpoint Denial of Service" and can be leveraged by adversaries to disrupt network security services. The Striker ISAKMP Protocol Test Suite specifically demonstrates this vulnerability, indicating that it was likely discovered through systematic protocol testing rather than accidental exploitation. The impact is particularly severe in environments where IPsec services are critical for secure communications, as the disruption can affect multiple network connections simultaneously. Organizations using affected OpenBSD versions must implement immediate mitigations to prevent exploitation, as the vulnerability represents a clear path to service disruption without requiring advanced technical skills or privileged access.
The recommended mitigation strategies include upgrading to OpenBSD versions that contain patches addressing this specific out-of-bounds read vulnerability, implementing network monitoring to detect unusual ISAKMP traffic patterns, and applying firewall rules to restrict access to IPsec services where possible. Additionally, system administrators should consider implementing intrusion detection systems that can identify and alert on malformed ISAKMP packets that match the vulnerability characteristics. The fix typically involves implementing proper bounds checking for SPI array sizes within delete payloads and ensuring that the isakmpd daemon gracefully handles malformed input rather than crashing. This vulnerability serves as a reminder of the importance of robust input validation in security-critical network protocols and the necessity of thorough testing of protocol implementations against malformed data inputs.