{
  "doc_id": "KB-PHISH-HEADER-CHECK",
  "doc_type": "kb",
  "title": "Phishing Header Validation Checklist",
  "scenario": "phishing",
  "summary": "Checklist for validating sender identity, domain reputation, and authentication results in suspected phishing emails.",
  "applicability": ["mail_suspicious_attachment", "mail_suspicious_link", "mail_bec_impersonation"],
  "key_points": ["Review SPF, DKIM, and DMARC alignment.", "Compare display name, envelope sender, and reply-to anomalies.", "Check domain age and known-good communication history."],
  "investigation_guidance": ["Use message trace and header parser.", "Compare sender domain with vendor allowlist.", "Escalate lookalike domains even when content appears business-relevant."],
  "decision_points": ["Newly observed domains with failed auth are high-risk.", "Benign vendor mail often has consistent historical sending patterns."],
  "related_entities": {"ttps": ["T1566.001"], "iocs": []},
  "related_refs": {"playbooks": ["PB-PHISH-001"], "cases": []},
  "tags": ["kb", "phishing", "email-header"],
  "updated_at": "2026-04-10T09:20:00+08:00"
}