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competition-mailbox-abuse

Lets your agent analyze enterprise mailbox abuse. Useful for understanding how emails can be misused.

What it does

This tool helps investigate how emails were misused in a company network. It tracks inbox rules, access permissions, and how emails were redirected to identify malicious activity.

When to use it

  • ✓When you suspect email rules were created to secretly redirect messages.
  • ✓When investigating unauthorized access to shared mailboxes.
  • ✓To understand how application permissions (OAuth) were used to access emails.

Example of what to ask your AI

“Investigate how an email was redirected from user X's inbox to sender Y.”

Want more? Open the sections below.

How to use

The easiest way: copy the message below and paste it into Claude, ChatGPT, Cursor or any AI. It reads the skill and follows the instructions.

Skill link

https://github.com/zhaoxuya520/reverse-skill/blob/main/CTF-Sandbox-Orchestrator/competition-mailbox-abuse/SKILL.md

Ready-to-paste message

Use this skill to help me: https://github.com/zhaoxuya520/reverse-skill/blob/main/CTF-Sandbox-Orchestrator/competition-mailbox-abuse/SKILL.md Read the SKILL.md file at that link and follow its instructions for my task.
How it works

The tool analyzes email logs, inbox rules, and access permissions. It reconstructs the chain of events to show how an email was diverted or improperly accessed.

Installation

Easiest way: copy the skill link and paste it into Claude, ChatGPT or Cursor asking it to follow the instructions.

In the terminal (Claude Code, Codex, Cursor), in your project folder:

npx skills add zhaoxuya520/reverse-skill --skill competition-mailbox-abuse

Or download just the file:

curl -L https://raw.githubusercontent.com/zhaoxuya520/reverse-skill/main/CTF-Sandbox-Orchestrator/competition-mailbox-abuse/SKILL.md -o SKILL.md
Technical content (original SKILL.md)

Original text by the author, straight from GitHub.

Competition Mailbox Abuse

Use this skill only as a downstream specialization after $ctf-sandbox-orchestrator is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to $ctf-sandbox-orchestrator first.

Use this skill when the decisive path runs through mailbox behavior, consent flow, or message-routing effects rather than generic AD evidence alone.

Reply in Simplified Chinese unless the user explicitly requests English.

Quick Start

  1. Decide whether the active path is phishing-to-consent, token-to-mailbox, rule-based persistence, or transport-level mail rerouting.
  2. Keep mailbox evidence, identity evidence, and message-trace evidence tied to the same user, mailbox, token, or message ID.
  3. Separate possession of a token or delegate edge from the actual mailbox effect it enables.
  4. Record forwarding targets, rule predicates, consent scopes, shared mailbox edges, and resulting mail flow in compact blocks.
  5. Reproduce the smallest mail effect that proves persistence, exfiltration, or privilege.

Workflow

1. Map The Mail Trust Path

  • Identify the principal, mailbox, token or session, consent grant, delegate edge, shared mailbox relationship, or app registration involved.
  • Record consent scopes, mailbox permissions, rule ownership, transport actions, and message-trace identifiers.
  • Distinguish client-visible symptoms from server-side mailbox or transport state.

2. Prove The Mailbox Effect

  • Correlate consent logs, sign-ins, message traces, inbox rules, transport rules, forwarding settings, and mailbox audit events.
  • Show which rule or token produces which concrete effect: silent forwarding, marking read, deletion, delegate access, or message rerouting.
  • Keep message IDs, sender or recipient pairs, and timestamps aligned across logs.

3. Reduce To The Decisive Abuse Chain

  • Compress the path to the smallest sequence: lure or grant -> token or delegate edge -> mailbox or transport mutation -> resulting mail effect.
  • State clearly whether persistence lives in consent, mailbox rules, transport config, or shared mailbox permissions.
  • If the task broadens into host pivots or Kerberos acceptance, switch back to the broader identity skill.

Read This Reference

  • Load references/mailbox-abuse.md for the consent checklist, rule checklist, and evidence packaging.

What To Preserve

  • Consent scopes, token claims, mailbox permissions, rule definitions, forwarding targets, and message IDs
  • Message-trace lines, audit events, and mailbox effects tied to the same mail path
  • The smallest replayable sequence that proves persistence, exfiltration, or delegate access
FAQ

What are 'transport rules'?

These are rules set up on the email server that can automatically move, copy, or redirect emails based on certain conditions.

What is 'OAuth consent'?

This is when an application asks for permission to access your email account on your behalf. The tool checks if this permission was misused.

What does 'persistence' mean in this context?

It means an attacker found a way to maintain access or control over the mailbox, even after the initial vulnerability was fixed.

Details

Original description by the author

Internal downstream skill for ctf-sandbox-orchestrator. CTF-sandbox workflow for enterprise mail abuse, OAuth consent, inbox or forwarding rules, transport rules, shared mailbox access, phishing chains, and token-to-mailbox side effects. Use when the user asks to trace mailbox rules, OAuth consent grants, forwarding or delegate abuse, shared mailbox access, message-trace evidence, or explain how m

repo: zhaoxuya520/reverse-skill

Popularity

GitHub stars
42k
Ranking position
#4726
License
MIT
Updated
9/22/2026

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