Executive Summary

Phishing and initial access broker campaigns remain the primary ingress vectors for enterprise compromises. This writeup outlines the triage methodology used to dissect deceptive inbound communications, examine mail transport headers, isolate obfuscated attachments, and establish educational guardrails for end users.

1. Header Triage & Origin Verification

When analyzing reported suspicious messages, raw email headers are prioritized over visual body content:

  • Authentication Alignment:
    • SPF (Sender Policy Framework): Verifies if the sending mail server IP is authorized by the domain’s SPF record.
    • DKIM (DomainKeys Identified Mail): Inspects cryptographic signatures (b= and bh= tags) to detect tampering during transport.
    • DMARC (Domain-based Message Authentication, Reporting, and Conformance): Verifies alignment between the RFC5322.From header and authentication results. Look for policy override flags or spoofing attempts on mismatched envelope senders.
  • Hop Analysis (Received: headers): Traces routing hops in reverse order to identify the true origin IP and detect relay abuse or external VPS redirectors.

2. Payload & Indicator of Compromise (IoC) Analysis

Suspicious Hyperlinks & Redirect Chains

  • Homograph & Typosquatting: Inspecting domain variations using lookalike UTF-8 characters or subtle character omissions.
  • URL Detonation: Routing links through sandboxed scanners (URLScan.io, VirusTotal) or local cURL inspection to extract full HTTP 301/302 redirection chains without exposing internal IP headers.

Attachment Inspection

  • Double Extensions & Obfuscated Macros: Identifying .pdf.exe, .iso, .vbs, or weaponized Office XML files containing embedded PowerShell commands.
  • Hash Extraction: Generating SHA-256 signatures of untrusted attachments to query threat intelligence platforms for pre-existing campaign associations.

3. Human Layer Defense: Incident Communication Framework

Technical controls must be paired with structured organizational awareness:

  • Indicators Guide: Authoring clear internal reference documentation detailing common social engineering cues (urgency prompts, irregular executive requests, external sender flags).
  • Feedback Loops: Establishing streamlined reporting protocols that empower staff to escalate anomalies without fear of reprimand.