hunt-csrf
**Hunt-CSRF** is a Claude Code skill for identifying Cross-Site Request Forgery vulnerabilities with emphasis on account takeover chains. It catalogs 15 real bug bounty cases including SameSite bypass variants, GraphQL mutation exploitation, CSRF token path-traversal, OAuth-state manipulation, and WebSocket CSRF, plus detection patterns for URL structures, cookie attributes, JavaScript token handling, and tech stacks prone to CSRF. Use this skill when auditing authentication flows, API endpoints, third-party integrations, and social platforms for high-impact CSRF vulnerabilities chaining to account compromise.
git clone --depth 1 https://github.com/elementalsouls/Claude-BugHunter /tmp/hunt-csrf && cp -r /tmp/hunt-csrf/skills/hunt-csrf ~/.claude/skills/hunt-csrfSKILL.md
## Shortcut: a raw HTTP client beats a real cross-origin page for header-check CSRF
A raw HTTP client (curl, Burp Repeater, any scripting client) is not a browser: it will send
whatever `Origin`/`Referer` header VALUE you set, from any path, on the same connection as your
authenticated cookie. Many apps that claim to defend against CSRF only do a naive **string check**
on the incoming `Origin`/`Referer` header (does it contain/equal some expected value?) rather than
real same-origin enforcement — you can satisfy that check directly by setting the header, with no
actual cross-site delivery (hosting an HTML page, a headless browser) required. This is faster and
more reliable than building a real attacker page for this exact pattern:
```
POST /profile HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Origin: https://a-domain-the-app-treats-as-trusted-or-attacker-controlled.example
Cookie: <authenticated session>
username=csrf_poc
```
If some text names a SPECIFIC origin/domain as the "expected" attacker page, that literal value is
often exactly what the server's check is looking for — try it verbatim in `Origin` (fall back to
`Referer` if `Origin` alone doesn't flip it). Only build a real cross-origin page (actual browser
delivery) when the target does genuine SameSite/fetch-based origin enforcement that a spoofed header
can't satisfy.
## Autonomous Testing Priority
**CSRF only matters on state-changing actions that a browser could be tricked into making cross-site.**
**Testing flow:**
1. **GET the form endpoint** to establish a baseline and check what fields exist (look for hidden `csrf_token`, `authenticity_token`, `_token`, `csrfmiddlewaretoken` fields).
2. **POST the state-changing action without any CSRF token field.** Send only the functional parameters (email, amount, etc.).
3. **Use a "simple-request" Content-Type** — `application/x-www-form-urlencoded`, `multipart/form-data`, OR `text/plain` are the three CORS "simple" content-types a cross-origin form can send with no preflight. A JSON endpoint is CSRF-resistant **only if the server rejects those** — if it also accepts a `text/plain` body (common), craft a `text/plain` payload that parses as valid JSON (see the JSON-CSRF-via-text/plain section). Don't skip a JSON endpoint on the assumption that `application/json` alone is protective.
4. **If the action succeeds (2xx, no "invalid token" error) → CSRF is confirmed.**
**High-value targets (in order of impact):**
- Email/password change → account takeover
- Money transfer or payment → financial fraud
- Admin actions (role assignment, user deletion)
- OAuth social-account linking → persistent ATO
**Token bypass techniques when a token IS present:**
- Omit the token field entirely — some frameworks only validate if the field exists, not if it's absent
- Send an empty value (`_token=`) — some validate format, not presence
- Copy a token from another session — some tokens aren't tied to the session
**Scope:** Don't test CSRF on login forms (no existing session to exploit), logout (no real impact), or read-only GET endpoints.
---
## Crown Jewel Targets
CSRF becomes high-value when it touches **state-changing actions with account-level or financial consequences**. The highest-paying targets are:
- **Account takeover vectors**: OAuth/SSO flows (RelayState manipulation), social account linking/unlinking (Oculus-Facebook, SocialClub), import-friends features that expose OAuth tokens
- **Authentication infrastructure**: Login CSRF, session fixation via CSRF, forced account association
- **API endpoints accepting cross-origin POST**: JSON APIs, heartbeat/activity APIs, anything that skips Content-Type enforcement
- **Third-party integrations**: Grafana, monitoring dashboards, embedded analytics — often lag on CSRF protections
- **Social platforms**: Twitter/X collections, friend imports, social graph mutations — high-volume, authenticated actions with real user impact
**Asset types that pay most:** Core product auth flows > API gateways > third-party integrations running on subdomains > admin panels.
---
## Attack Surface Signals
### URL Patterns
```
/oauth/authorize?RelayState=
/accounts/link
/import/friends
/api/v*/heartbeat
/api/v*/collect
/monitoring/* (Grafana, Prow, Prometheus)
/auth/saml/callback
/connect/* (social integrations)
```
### Response Header Signals
```
# Missing or weak SameSite cookie attributes
Set-Cookie: session=abc123; HttpOnly # no SameSite = vulnerable
Set-Cookie: session=abc123; SameSite=None # explicitly allows cross-site
# Missing CSRF headers
# No X-Frame-Options or permissive CORS
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true # dangerous combo
```
### JS / DOM Patterns
```javascript
// Static or predictable CSRF tokens
meta[name="csrf-token"] // grep if value changes across sessions
authenticity_token // Rails — check if reused across page loads
// JSON endpoints without Content-Type enforcement
fetch('/api/heartbeat', {method: 'POST', body: JSON.stringify(data)})
// No CSRF token in form at all
<form method="POST" action="/accounts/link"> // no hidden token field
```
### Tech Stack Signals
- **Rails apps**: Look for `authenticity_token` — test if it's static per session
- **Django apps**: Check `csrfmiddlewaretoken` — test cross-user/session reuse
- **Grafana instances**: CVE-2022-21703 — check version via `/api/health`
- **SAMLv2/OIDC flows**: `RelayState` parameter rarely validated
- **Express/Node APIs**: Often skip CSRF middleware on `/api/*` routes
---
## Step-by-Step Hunting Methodology
1. **Map all state-changing endpoints** — Spider authenticated session, filter for POST/PUT/DELETE/PATCH. Note every form and AJAX call.
2. **Check cookie SameSite attributes** — In DevTools → Application → Cookies. Flag any session cookie without `SameSite=Strict` or `Lax`.
3. **Test token staticness** — Log in twice (different sessions or incognito). Compare `authenticity_token` / `csrfmiddleEnd-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.