# Investigating Phishing Email Incident

> Use when investigates phishing email incidents from initial user report through header analysis, URL/attachment detonation, impacted user identification, and containment actions using SOC tools like Splunk, Microsoft Defender, and sandbox analysis platforms. Use when a reported phishing email requires full incident investigation to determine scope and impact.

- Skill: `oyi77/investigating-phishing-email-incident` (Agent Skill)
- Install (CLI): `npx skillmds add oyi77/investigating-phishing-email-incident`
- Raw SKILL.md: https://api.skillmd.com/api/skills/oyi77/investigating-phishing-email-incident/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Docs & Writing
- License: Apache-2.0
- Author: oyi77 (https://skillmd.com/u/oyi77)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/oyi77/investigating-phishing-email-incident

---


# Investigating Phishing Email Incident

## Overview

Cybersecurity skill for investigating phishing email incident. Follows industry best practices and security standards.

## When to Use

**Trigger phrases:**
- "investigating phishing email incident"
- "A user reports a suspicious email via the phishing report button or helpdesk tic"
- "Email security gateway flags a message that bypassed initial filters"
- "Automated detection identifies credential harvesting URLs or malicious attachmen"


Use this skill when:
- A user reports a suspicious email via the phishing report button or helpdesk ticket
- Email security gateway flags a message that bypassed initial filters
- Automated detection identifies credential harvesting URLs or malicious attachments
- A phishing campaign targeting the organization requires scope assessment

**Do not use** for spam or marketing emails without malicious intent — route those to email administration for filter tuning.


## When NOT to Use

- When you lack proper authorization for testing
- For production systems without change management
- When the task requires legal or compliance expertise beyond technical scope


## Prerequisites

- Access to email gateway logs (Proofpoint, Mimecast, or Microsoft Defender for Office 365)
- Splunk or SIEM with email log ingestion (O365 Message Trace, Exchange tracking logs)
- Sandbox access (Any.Run, Joe Sandbox, or Hybrid Analysis) for URL/attachment detonation
- Microsoft Graph API or Exchange Admin Center for email search and purge operations
- URLScan.io and VirusTotal API keys

## Workflow

```python
# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}
```

1. **Define Objectives** — Clarify the goals and scope for phishing email incident.
2. **Gather Resources** — Collect tools, data, and access needed for phishing email incident.
3. **Execute Process** — Carry out phishing email incident operations methodically.
4. **Verify Quality** — Check results against acceptance criteria.
5. **Document Outcomes** — Record findings, decisions, and next steps.

## Tools

- **Analysis Platform** — Data processing and visualization
- **Collaboration Tools** — Team coordination and knowledge sharing


## Process

1. **Reconnaissance** — Gather target information, identify attack surface, enumerate services
1. **Analysis/Exploitation** — Execute the technique, analyze results, document findings
1. **Reporting** — Document IOCs, write findings, provide remediation recommendations

## Verification

- [ ] All phishing email incident procedures executed completely and documented
- [ ] Findings validated against multiple data sources
- [ ] False positives identified and filtered
- [ ] Results documented with evidence and timestamps
- [ ] Recommendations provided with risk-based prioritization

## Anti-Rationalization Table

| Rationalization | Reality |
|---|---|
| "We are too small to be targeted" | Automated attacks target everyone. Size does not matter. |
| "Security slows us down" | A breach slows you down 100x more. Build security in from the start. |
| "We will fix it after launch" | Vulnerabilities in production are exploited within hours. Fix before deploy. |