Extract and analyze JA3/JA3S TLS fingerprints from SSL logs. Identifies client TLS implementations and can detect known malicious fingerprints. JA3 fingerprints persist even when domains/IPs change, making them valuable for tracking threat actors.
AI agents call zeek_ja3_fingerprints to retrieve information from Zeek without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and analyzes existing security log data (JA3/JA3S fingerprints from SSL logs) to identify TLS implementations and detect known threats. It performs pattern matching and lookups against known malicious fingerprints but does not create, modify, delete, execute code, move money, or trigger external operations. The analysis is passive observation of network security monitoring data.
From the tool's definition Tool 'zeek_ja3_fingerprints' extracts and analyzes TLS fingerprints from SSL logs; performs identification and detection of known malicious fingerprints.
Attacks that exploit this kind of access
Extract and analyze JA3/JA3S TLS fingerprints from SSL logs. Identifies client TLS implementations and can detect known malicious fingerprints. JA3 fingerprints persist even when domains/IPs change, making them valuable for tracking threat actors. It is categorised as a Read tool in the Zeek MCP Server, which means it retrieves data without modifying state.
Register the Zeek MCP server in PolicyLayer and add a rule for zeek_ja3_fingerprints: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Zeek. Nothing to install.
zeek_ja3_fingerprints is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the zeek_ja3_fingerprints rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for zeek_ja3_fingerprints. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
zeek_ja3_fingerprints is provided by the Zeek MCP server (solomonneas/zeek-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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