KeyUpdate Message Induced DoS in Go

Executive Summary

This vulnerability involves a flaw in how handshake messages, specifically KeyUpdate, are processed. Normally, these messages should only advance the state after a handshake is complete. However, in this case, the server treats every KeyUpdate message as state-advancing, even if no handshake has occurred. This allows an attacker to repeatedly send KeyUpdate messages, forcing the server to continuously perform key derivation operations without end.

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Detection Guidance

Detecting this vulnerability requires monitoring for unusual TLS handshake activity, particularly repeated KeyUpdate messages before handshake completion. Check server logs for excessive KeyUpdate handshake messages or continuous key derivation operations. Use network monitoring tools like Wireshark to inspect TLS 1.3 handshake sequences for anomalies. Ensure your Go version is updated to a patched release.

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Impact Analysis

This vulnerability can lead to denial-of-service conditions. An attacker could exploit it to consume excessive server resources, causing performance degradation or complete service unavailability. Systems relying on secure handshakes for communication may become unresponsive or crash under sustained attack.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling denial-of-service attacks through excessive key derivation operations. This may lead to service disruptions, affecting data availability and integrity, which are critical under these regulations.

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Mitigation Strategies

Update Go to the latest version to patch the vulnerability. Monitor network traffic for excessive KeyUpdate messages. Implement rate limiting on handshake operations.

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