hunt-oauth
The hunt-oauth skill identifies high-value OAuth vulnerabilities across web and mobile targets by providing reconnaissance patterns, attack surface signals, and exploitation methodologies derived from 19 public bug bounty reports. Use this skill when testing authentication flows on consumer identity providers, multi-tenant SaaS platforms, mobile apps with deep link handlers, or enterprise SSO connectors where OAuth flaws enable account takeover and typically command substantial bounties.
git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter /tmp/hunt-oauth && cp -r /tmp/hunt-oauth/skills/hunt-oauth ~/.claude/skills/hunt-oauthSKILL.md
## Crown Jewel Targets
OAuth vulnerabilities are among the highest-value bug classes in web security because they directly enable **account takeover, session theft, and authentication bypass** — the trifecta that programs pay most for.
**Highest-value targets:**
- **Consumer identity providers** (Google, Facebook, PayPal, Apple SSO integrations) — any compromise cascades across all relying parties
- **Mobile apps with custom deep link OAuth handlers** — Android/iOS intent handling is notoriously loose
- **Multi-tenant SaaS platforms** (GitLab, Reddit-scale apps) where one OAuth flaw hits millions of accounts
- **Gaming/entertainment platforms** with federated login (Rockstar, Oculus) — often security-immature teams
- **Enterprise SSO connectors** — critical infrastructure, high severity payouts
**Asset types that pay most:**
- OAuth authorization endpoints (`/oauth/authorize`, `/connect/authorize`)
- Token exchange endpoints (`/oauth/token`)
- Mobile deep link handlers (`push_notification_webview`, custom scheme URIs)
- Social login callback handlers (`/auth/callback`, `/oauth/callback`)
**Typical payouts:** $500–$20,000+ depending on program; account takeover findings often hit max bounty.
---
## Attack Surface Signals
### URL Patterns to Hunt
```
/oauth/authorize
/oauth/token
/connect/authorize
/auth/callback
/oauth/callback
/login?redirect_uri=
/signin?next=
/auth?return_to=
/oauth/redirect
/push_notification_webview
```
### Response Headers That Signal OAuth
```
Location: https://accounts.example.com/oauth/...
Set-Cookie: oauth_state=
WWW-Authenticate: Bearer
Content-Type: application/json (with access_token in body)
```
### JavaScript Patterns (grep in JS bundles)
```javascript
redirect_uri
client_id
response_type=code
response_type=token
state=
nonce=
oauth_token
access_token
push_notification_webview
deeplink
intent://
```
### Tech Stack Signals
- Android apps with `intent-filter` in `AndroidManifest.xml` handling `http://` or custom scheme URIs
- Apps using Doorkeeper, OmniAuth, Devise (Ruby), Passport.js (Node), Spring Security OAuth
- Social login buttons (Google, Facebook, Apple) = OAuth surface guaranteed
- `.well-known/openid-configuration` present = full OIDC surface available
---
## Step-by-Step Hunting Methodology
1. **Enumerate all OAuth entry points**
- Spider the app for `/oauth`, `/connect`, `/auth`, `/login` paths
- Check `.well-known/openid-configuration` and `.well-known/oauth-authorization-server`
- Decompile mobile APKs: `apktool d app.apk` and grep for `redirect_uri`, `intent://`, deep link schemes
2. **Map the full OAuth flow**
- Capture the authorization request: note `client_id`, `redirect_uri`, `state`, `nonce`, `response_type`
- Capture the callback: note where tokens/codes land, what validates state/nonce
3. **Test `redirect_uri` validation (highest yield)**
- Try exact host bypass: `redirect_uri=https://legit.com.evil.com`
- Try path traversal: `redirect_uri=https://legit.com/callback/../../../evil`
- Try open redirects on the legitimate domain first, then chain into OAuth
- Try parameter pollution: `redirect_uri=https://legit.com&redirect_uri=https://evil.com`
- Try encoded characters: `%2F`, `%40`, `%23` to confuse parsers
4. **Test `state` parameter (CSRF)**
- Remove `state` entirely — does the flow complete?
- Reuse a fixed `state` value across sessions
- Check if `state` is validated server-side or only client-side
5. **Test `nonce` parameter (replay/bypass)**
- Capture a nonce from one flow, attempt to replay it in another
- Check if nonce is validated after token exchange
- Test if nonce can be extracted via referrer leak (step 9)
6. **Test authentication step completeness**
- For multi-step auth (e.g., email verification + OAuth): can you skip to `/oauth/token` directly?
- Check if partial auth state (unverified email) is accepted by the token endpoint
7. **Hunt referrer leakage**
- After OAuth callback with tokens in URL fragment or query, check if any on-page resources (images, scripts, iframes) receive the full `Referer` header
- Look specifically at language switchers, analytics calls, social share buttons triggered post-auth
8. **Test mobile deep links**
- For Android: craft malicious intent URIs that redirect the OAuth webview to attacker-controlled URLs
- Check if deep link handlers validate the origin/host before loading
- Test `push_notification_webview` patterns that accept arbitrary URLs
9. **Test misconfigured client credentials**
- Check if `client_secret` appears in JS bundles or APK resources
- Test if token endpoint accepts arbitrary `redirect_uri` values when combined with leaked `client_id`/`client_secret`
10. **Verify and document**
- Confirm state is not validated → CSRF to account link
- Confirm token lands on attacker domain → session theft
- Confirm email verification skippable → auth bypass
- Run Gate 0 check before reporting
---
## Payload & Detection Patterns
### redirect_uri Bypass Payloads
```
# Host confusion
https://evil.com#legit.com
https://legit.com.evil.com
https://legit.com@evil.com
# Path traversal
https://legit.com/oauth/callback/../../redirect?url=https://evil.com
# Open redirect chain (find open redirect on legit domain first)
https://legit.com/logout?next=https://evil.com
# Parameter pollution
?redirect_uri=https://legit.com/cb&redirect_uri=https://evil.com/cb
# URL encoded slashes
https://legit.com%2F@evil.com
https://legit.com%252F..%252F..evil.com
```
### State CSRF Test
```bash
# Step 1: Initiate OAuth flow, capture state value
# Step 2: Drop request, use attacker account's link with victim's session
curl -v "https://target.com/oauth/authorize?client_id=APP&redirect_uri=https://target.com/cb&response_type=code&state=FIXED_VALUE"
# Step 3: Force victim to visit callback with attacker's code + fixed state
https://target.com/oauth/callback?code=ATTACKER_CODE&state=FIXED_VALUE
```
### NEnd-to-end Android APK red-team pipeline — automated APK acquisition (Play Store + apkpure + apkmirror fallback), jadx decompilation, secret/URL/JWT/Firebase grep, pinned-cert extraction, exported-component enumeration, Frida runtime instrumentation templates, intent-injection probes. Built from an authorized external red-team engagement where 7 APKs were pulled manually, 4 download attempts truncated, and a hardcoded JWT + 30 internal API endpoints were recovered from one of the apps. Use when target has a mobile app catalogue (Play Store developer page), when you find an APK URL hosted on a web server, or when post-recon mentions "mobile app" in scope.
Run autonomous hunt loop on a target — scope check → recon → rank surface → hunt → validate → report with configurable checkpoints. Usage: /autopilot target.com [--paranoid|--normal|--yolo]
Local-tooling companion to the bug-bounty orchestrator — carries the SAME complete bug-bounty workflow, but reach for THIS variant when you also need to resolve where tools, wordlists, and clones are installed on the local machine (jhaddix, SecLists, trufflehog, ffuf, dalfox, ghauri); for pure orchestration/routing use the bug-bounty skill. Workflow it covers — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use when you need the local install path of a tool / wordlist / clone for a hunt, or as the full-workflow variant when operating from this local toolkit; for general routing use the bug-bounty skill. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Use at the START of any bug bounty hunting session, when switching targets, or when feeling lost about what to do next. Master orchestrator that combines the 5-phase non-linear hunting workflow with the critical thinking framework (developer psychology, anomaly detection, What-If experiments). Routes to all other skills based on current hunting phase. Also use when asking "what should I do next" or "where am I in the process.
Complete bug bounty workflow — recon (subdomain enumeration, asset discovery, fingerprinting, HackerOne scope, source code audit), pre-hunt learning (disclosed reports, tech stack research, mind maps, threat modeling), vulnerability hunting (IDOR, SSRF, XSS, auth bypass, CSRF, race conditions, SQLi, XXE, file upload, business logic, GraphQL, HTTP smuggling, cache poisoning, OAuth, timing side-channels, OIDC, SSTI, subdomain takeover, cloud misconfig, ATO chains, agentic AI), LLM/AI security testing (chatbot IDOR, prompt injection, indirect injection, ASCII smuggling, exfil channels, RCE via code tools, system prompt extraction, ASI01-ASI10), A-to-B bug chaining (IDOR→auth bypass, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth), bypass tables (SSRF IP bypass, open redirect bypass, file upload bypass), language-specific grep (JS prototype pollution, Python pickle, PHP type juggling, Go template.HTML, Ruby YAML.load, Rust unwrap), and reporting (7-Question Gate, 4 validation gates, human-tone writing, templates by vuln class, CVSS 3.1, PoC generation, always-rejected list, conditional chain table, submission checklist). Use for ANY bug bounty task — starting a new target, doing recon, hunting specific vulns, auditing source code, testing AI features, validating findings, or writing reports. 中文触发词：漏洞赏金、安全测试、渗透测试、漏洞挖掘、信息收集、子域名枚举、XSS测试、SQL注入、SSRF、安全审计、漏洞报告
Bugcrowd-specific reporting tactics complementing report-writing: VRT category search-and-fallback strategy when no exact match exists, manual severity override when VRT defaults underrate impact, severity-request paragraph as first body section, OOS-clause rebuttal templates (rate limiting on auth-flow endpoints, debug-info framing, user-enumeration with sensitive PII, theoretical-issue counter), chained-finding cross-reference patterns, target selection for QA-vs-prod programs, researcher-side hygiene (Bugcrowdninja email alias, account state restoration, friendly-tester posture). Use when filing a Bugcrowd submission, when VRT default seems wrong, when triager closes as OOS or downgrades severity, when chaining linked submissions, or when scope distinguishes production from QA. Pairs with report-writing and triage-validation.
Build an exploit chain — given bug A, finds B and C to combine for higher severity and payout. Knows common chain patterns: IDOR→ATO, SSRF→cloud metadata, XSS→ATO, open redirect→OAuth theft, S3→bundle→secret→OAuth. Usage: /chain
Cloud IAM red-team attack chain across AWS, Azure, GCP — focused on EXTERNAL exploitation paths and post-credential-discovery privilege analysis. Covers IAM enumeration (aws iam, az role, gcloud iam), STS/AssumeRole chaining, Azure Managed Identity abuse (via SSRF/leak), GCP service account JSON abuse, IMDSv1/v2 attacks via SSRF, K8s ServiceAccount token privilege analysis once held (token discovery / cluster exposure is owned by hunt-k8s), role-trust-policy confused-deputy, cross-account assume-role enumeration, IAM privilege escalation patterns (24+ AWS, 8+ Azure, 6+ GCP), and AWS Cognito Identity Pool unauthenticated-role attack chain (GetId → GetCredentialsForIdentity → IAM role abuse). Built for the case where recon yields a credential (key, JSON, token) and you need to know what it grants and how to escalate. Use when an AWS key / Azure secret / GCP service account JSON / K8s SA token surfaces from a code repo, JS bundle, APK, breach corpus, or SSRF chain.