Phishing Retro Hunt

1. Prerequisites

• Access to a list of IOCs
  • Sender addresses/domains
  • Subject lines
  • URLs
  • Attachment hashes
  • Email timestamps
  • Threat intel indicators
• Access to email platform (Microsoft 365, Google Workspace)
• SIEM / log platform access
• EDR platform access
• Proxy / DNS logs access
• Threat intel platform access

2. Step-by-Step Instructions

1. Identify Core Indicators

   • Collect:
     • Sender domains
     • Reply-To addresses
     • URLs
     • Attachment hashes
     • IP addresses
     • Subjects

2. Search Email Environment:

   • Search for:

     • Matching sender
     • Similar subject lines
     • Same URLs
     • Same attachment hashes

   • Determine:

     • Number of recipients
     • Delivery status
     • User interaction

3. Identify Click Activity

   • Review:
     • Email click logs
     • Proxy logs
     • DNS resolution events
   • Determine:
     • Which users accessed phishing infrastructure
     • Timestamp correlation

4. Hunt for Credential Exposure

   • Review IdP logs for:
     • Suspicious logins
     • Impossible travel
     • MFA anomalies
     • Unusual devices

5. Hunt for Malware Execution (If Applicable)

   • Search EDR telemetry for:
     • Hash execution
     • Process creation
     • Network connections
     • Child process behaviour

6. Identify Campaign Scope

   • Determine:
     • Total users targeted
     • Total users interacted
     • Departments impacted
     • Geographic spread (if relevant)

7. Add Additional Detection Logic

   • Deploy temporary detections for:
     • Domains
     • URLs
     • Hashes
     • IPs
     • Behaviour patterns

3. Post-Action

• Document all findings in the incident ticket

Contributor

Vishal Thakur GitHub: https://github.com/malienist

Contributed to the Arcana Incident Response Documentation Framework.