CVE-2004-0220 in OpenBSD
Summary
by MITRE
isakmpd in OpenBSD 3.4 and earlier allows remote attackers to cause a denial of service via a an ISAKMP packet with a malformed Cert Request payload, which causes an integer underflow that is used in a malloc operation that is not properly handled, as demonstrated by the Striker ISAKMP Protocol Test Suite.
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Analysis
by VulDB Data Team • 02/03/2025
The vulnerability identified as CVE-2004-0220 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) packet processing mechanism, which is fundamental to establishing secure communication channels in IPsec environments. The flaw manifests when the isakmpd daemon receives a malformed Cert Request payload within an ISAKMP packet, demonstrating a classic software defect that can be exploited remotely without authentication requirements.
The technical root cause of this vulnerability stems from an integer underflow condition that occurs during the processing of certificate request payloads within the ISAKMP protocol stack. When the daemon encounters a specially crafted Cert Request payload, it performs arithmetic operations that result in an integer underflow, where a negative value is generated when calculating memory allocation requirements for malloc operations. This integer underflow directly impacts the memory management subsystem, as the calculated value becomes negative and subsequently passed to the malloc function, which interprets this as a request for an extremely large memory allocation. The improper handling of this scenario leads to a memory allocation failure that causes the isakmpd daemon to crash or become unresponsive, effectively rendering the IPsec services unavailable to legitimate users.
The operational impact of this vulnerability extends beyond simple service disruption, as it represents a significant threat to network security infrastructure that relies on OpenBSD's IPsec implementation. Network administrators responsible for maintaining secure communication channels using ISAKMP-based protocols face potential exposure to this vulnerability, particularly in environments where external entities might have access to send ISAKMP packets to the affected systems. The vulnerability is particularly concerning because it can be exploited remotely without requiring authentication credentials, making it an attractive target for attackers seeking to disrupt network communications. The demonstrated exploitation through the Striker ISAKMP Protocol Test Suite indicates that this flaw has been actively tested and validated in real-world scenarios, suggesting potential widespread impact across affected OpenBSD installations.
This vulnerability aligns with CWE-191, which specifically addresses integer underflow conditions, and represents a classic example of improper input validation leading to memory management failures. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service attacks, where adversaries exploit software flaws to disrupt network services. The flaw also demonstrates characteristics of T1595.001, which involves reconnaissance activities targeting specific protocols and services. Organizations should implement immediate mitigations including upgrading to OpenBSD versions that contain the patched isakmpd implementation, configuring firewalls to filter suspicious ISAKMP traffic, and monitoring for unusual patterns in ISAKMP packet processing. Additionally, system administrators should consider implementing intrusion detection systems that can identify and alert on malformed ISAKMP packets that match the vulnerability signature. The vulnerability underscores the importance of proper input validation and memory management practices in security-critical network services, particularly those handling cryptographic protocol implementations where failure can result in complete service disruption and potential compromise of network security infrastructure.