# Competition Mailbox Abuse

Internal downstream skill for ctf-sandbox-orchestrator.

- Repository: https://github.com/zhaoxuya520/reverse-skill (43923 stars)
- Category: Engineering
- License: MIT
- Last updated: 2026-09-22
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add zhaoxuya520/reverse-skill --skill competition-mailbox-abuse -g -a claude-code -y`
Codex: `npx skills add zhaoxuya520/reverse-skill --skill competition-mailbox-abuse -g -a codex -y`
Cursor: `npx skills add zhaoxuya520/reverse-skill --skill competition-mailbox-abuse -g -a cursor -y`
Gemini CLI: `npx skills add zhaoxuya520/reverse-skill --skill competition-mailbox-abuse -g -a gemini-cli -y`

## Description

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 mail artifacts turn into persistence, exfiltration, or privilege. Use only after `$ctf-sandbox-orchestrator` has already established sandbox assumptions and routed here.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# 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

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