ACK Packet ID Integer Overflow in OpenVPN

Executive Summary

This vulnerability involves retransmissions of ACK packet IDs in OpenVPN versions up to 2.6.22 and 2.7.6. Remote unauthenticated attackers can exploit crafted inputs to trigger a timeout integer overflow, leading to a denial of service.

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Detection Guidance

This vulnerability involves retransmissions of ACK packet IDs in OpenVPN causing a denial of service via timeout integer overflow. Detection requires monitoring for unusual retransmission patterns or timeouts in OpenVPN traffic. Check OpenVPN logs for repeated ACK retransmissions or connection timeouts. Use network monitoring tools like tcpdump or Wireshark to capture and analyze OpenVPN traffic for abnormal retransmission behavior.

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Impact Analysis

The vulnerability allows attackers to cause a denial of service, which could disrupt VPN services and prevent legitimate users from accessing network resources.

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Compliance Impact

The vulnerability allows remote unauthenticated attackers to cause a denial of service via crafted inputs that trigger a timeout integer overflow. This could disrupt VPN services, potentially leading to unauthorized access or data exposure, which may impact compliance with GDPR or HIPAA by compromising data integrity or availability.

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Mitigation Strategies

Update OpenVPN to a version later than 2.6.22 or 2.7.6 to address the ACK packet retransmission issue. Monitor network traffic for unusual retransmission patterns that may indicate exploitation attempts.

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