Unveiling Hidden Connections: JA4 Client Fingerprinting on VirusTotal

This document introduces JA4 TLS client fingerprinting as a more robust successor to JA3, detailing how it derives stable identifiers from the TLS Client Hello (version, cipher suites, extensions, ALPN). It shows how analysts can pivot in VirusTotal via behavior_network searches (including wildcard patterns on JA4 components) and automate detections with YARA rules using the vt module, enabling clustering of related samples and improved hunting for suspicious TLS client behaviors.