oauth

oauth is a skill for Claude Code, Codex from MingyiSecLab/Mingyi-Atlas. It costs 41 tokens per session (1,803 once invoked), scanned A, a copy of oauth, Apache-2.0.

A security testing guide for OAuth 2.0 and OpenID Connect, standards that let applications sign users in and access approved account data. It examines errors in redirects, state checks, tokens, scopes, and PKCE.

In plain words
What is it for?
It is for mapping OAuth and OIDC endpoints, reviewing normal authorization flows, and testing redirect URLs, CSRF protection, response types, scopes, and PKCE settings.
Why use it?
It helps find account-takeover risks caused by incorrectly implemented login and authorization flows. These bugs can leak authorization codes, bypass protections, or grant too much access.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit It is for mapping OAuth and OIDC endpoints, reviewing normal authorization flows, and testing redirect URLs, CSRF protection, response types, scopes, and PKCE settings.

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Install with agentmods
npx agentmods add skills/mingyiseclab/mingyi-atlas/oauth
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add MingyiSecLab/Mingyi-Atlas --skill oauth
Clone the repo
git clone --depth 1 https://github.com/MingyiSecLab/Mingyi-Atlas

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for oauth

README.md
[![agentmods](https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/oauth/github.svg)](https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/oauth)
Your own site
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/oauth"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/oauth/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for oauth

Your own site · 80×15
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/oauth"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/oauth.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,803 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00041 $0.01803
Opus 5 $0.00020 $0.00901
Sonnet 5 $0.00008 $0.00361
Haiku 4.5 $0.00004 $0.00180

Measured 7d ago against content hash 25a010cb53a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

oauth scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -s https://target/.well-known/openid-configuration | jq
Origin

This is a copy

100% identical to oauth — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

src/skills/standard/exploit/web/oauth/SKILL.md · 168 lines

How it starts

The opening of the file, as written. The whole thing — 168 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OAuth / OIDC Attack Playbook

OAuth bugs are the single highest-paying ATO vector in modern bug bounty. Every B2B SaaS has an OAuth surface; many implement it wrong.

1. Map the flow

# Discovery
curl -s https://target/.well-known/openid-configuration | jq

# Key endpoints to identify:
# - /authorize  (where redirect_uri/client_id/scope arrive)
# - /token      (where code exchanges for tokens)
# - /userinfo   (claims about user)
# - /jwks.json  (signing keys, see jwt/SKILL.md)
# - /revoke     (sometimes overpermissive)

Capture a normal flow in Burp. Note: client_id, redirect_uri, state, scope, response_type, code_challenge (PKCE).

2. Attack surface

2.1 redirect_uri bypass

The #1 OAuth bug class. Server's allowlist regex is too loose:

Bypass Example
Path append https://target.com/callback/../../evil
Subdomain wildcard https://target.com.evil.com/cb (server matches *.target.com)
Userinfo trick https://[email protected]/cb
Path-traversal in fragment https://target.com/cb#@evil.com
Open-redirect chain redirect_uri=https://target.com/known-redirect?to=evil.com
Localhost / loopback redirect_uri=http://localhost:1337 (often allowlisted)
data: URI redirect_uri=data:text/html,<script>... (rare but devastating)
Mixed-protocol http:// accepted where https:// required
URL-encoded slash https://target.com%2Fcallback%[email protected]
Different fragment behavior redirect_uri=https://evil.com#https://target.com/cb

Test ALL of these. paramspider + Burp Intruder w/ payload list = systematic.

2.2 State parameter missing / weak (CSRF)

state should bind the auth request to the user's session. Missing or predictable state → attacker initiates OAuth in own browser, sends victim the URL, victim clicks → attacker's account now linked to victim's identity.

GET /authorize?response_type=code
    &client_id=...
    &redirect_uri=https://target.com/cb
    &state=                          ← empty or predictable

Read the full file on GitHub · 168 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 168 lines · 41 tokens per session scan A 25a010cb53a4

Subscribe to this mod's changes

oauth is a skill published in the GitHub repository MingyiSecLab/Mingyi-Atlas (11 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 41 tokens to every session and 1,803 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to oauth, differing in 0 lines, and is treated as a copy.