investigating-phishing-email-incident

Investigates phishing email incidents through header analysis, URL detonation, scope assessment, and containment.

954|172|Updated Mar 13, 2026
One-click install
npx skills add https://github.com/xalgord/xalgorix --skill investigating-phishing-email-incident
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: investigating-phishing-email-incident
Source: https://github.com/xalgord/xalgorix/tree/main/internal/tools/skills/data/soc-operations/investigating-phishing-email-incident
Command: npx skills add https://github.com/xalgord/xalgorix --skill investigating-phishing-email-incident

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

When a user reports a suspicious email, SOC analysts need a repeatable process to determine whether it is malicious, how many users received it, who clicked or submitted credentials, and how to contain the threat across mailboxes, proxies, and endpoints.

Core Features & Use Cases

  • Header and Authentication Analysis: Parse .eml files to extract Received chains, SPF, DKIM, and DMARC results, and detect display-name spoofing or Reply-To mismatches.
  • URL and Attachment Detonation: Submit phishing URLs to URLScan.io and VirusTotal, hash attachments, and detonate files in sandboxes like Any.Run or Joe Sandbox to catch delayed or cloaked payloads.
  • Scope and Impact Assessment: Use Splunk message trace queries and Microsoft Graph API to find all campaign recipients, then check proxy logs for clicks and credential-submission POSTs.
  • Containment and Reporting: Purge emails via Compliance Search, block domains and hashes, force password resets with session revocation, and produce a structured incident report.
  • Use Case: A finance employee reports an "Urgent: Password Reset Required" email. The skill walks through header validation, URL detonation revealing a credential harvester, a Splunk search finding 47 recipients, proxy analysis confirming 2 credential submissions, and full containment with purge and password resets.

Quick Start

Investigate the reported phishing email in the attached .eml file, determine the campaign scope and impacted users, and recommend containment actions.

Frequently Asked Questions about investigating-phishing-email-incident

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I investigate a reported phishing email?

Start by extracting full headers from the .eml file and checking SPF, DKIM, and DMARC results. Then detonate URLs and attachments in a sandbox, search message traces for all recipients, check proxy logs for clicks and credential submissions, and finish with purge, blocking, and password resets.

How to find all recipients of a phishing campaign in Splunk?

Query the O365 message trace index filtering by sender address, subject, or Message-ID over the campaign window. Pivot on sending IP, URL domain, and body hash to catch rotated subjects and senders that a single-subject search would miss.

Does SPF DKIM DMARC pass mean an email is legitimate?

No. A dmarc=pass from a lookalike or freshly registered domain, or a compromised authenticated mailbox used for thread hijacking, still delivers phishing. Check domain age, display-name spoofing, and Reply-To or Return-Path mismatches alongside authentication results.

How do I know who clicked a phishing link or submitted credentials?

Search proxy logs for requests to the phishing domain grouped by user and source IP. Distinguish clicks (GET requests) from credential submissions by filtering for HTTP POST requests to the phishing URL, then force password resets for submitters.

Why does sandbox analysis miss malicious phishing URLs?

Attackers serve benign pages to sandboxes and only redirect to the harvester on a second visit, specific geo, or matching User-Agent. Re-scan from a realistic egress, follow the full redirect chain, and extract URLs from PDFs, QR codes, and HTML attachments.

When should a suspicious email not be handled as a phishing incident?

Spam or marketing emails without malicious intent should be routed to email administration for filter tuning rather than incident investigation. Confirmed bulk senders can be handled through gateway filtering instead of incident queues.