Entity Extraction

Entity Extraction

Entities drive correlation, enrichment and response targets, so they must be correct, typed, and normalized. Validate every value with prompt-injection-defense rules.

Field paths

Windows hashes fields look like SHA256=…,MD5=…: split and type each.

Wazuh puts extra metadata next to these values: agent.ip is the agent's registered address (NAT'd hosts all show the same one), manager.name is the Wazuh manager (never an entity), and location is the log source (file path or channel), not a host. Rules that interpolate fields into rule.description (e.g. rule 87105 VirusTotal with the file path) repeat attacker-supplied values. Extract from the structured field, not the description.

Normalization

• IPs: strip ports (1.2.3.4:22 → 1.2.3.4), drop IPv6 zone ids, lowercase IPv6.
• Hosts: lowercase; keep FQDN if present; always include the Wazuh agent.id in enrichment so responders can target it.
• Users: keep domain prefix (CORP\alice → value corp\alice); lowercase.
• Hashes: lowercase hex; type by length (32 md5, 40 sha1, 64 sha256).
• Domains: lowercase, strip trailing dot.
• Files/processes: keep full path; don't normalize case on Linux.

Roles

• attacker — the entity performing the suspicious activity (source IP of brute force, user who ran the malicious command).
• victim — the entity acted upon (target host, targeted account, modified file).
• observed — related but role unclear (a process in the tree, a hash seen).

Private (RFC 1918 / loopback / link-local) source IPs are attacker only if the evidence supports it; otherwise observed. Loopback is never an attacker.

Caps and dedup

• Max 50 entities per type per update; dedupe by (type, value).
• Keep counts in enrichment.count and first/last seen timestamps when known.

Entity object

jsonCopy code
{"type": "ip", "value": "203.0.113.7", "role": "attacker",
 "enrichment": {"field": "data.srcip", "count": 42, "first_seen": "...", "last_seen": "...", "private": false}}

For hosts add "agent_id": "001" inside enrichment.

Output

• add_entities(case_id, entities) with validated, normalized objects.
• If values were rejected or truncated, add_finding titled Entity extraction notes listing what was dropped and why.