idor-vulnerability-hunting

idor-vulnerability-hunting is a skill for Claude Code, Codex from ShulkwiSEC/bb-huge. It costs 77 tokens per session (3,178 once invoked), scanned A, original, MIT.

A security-testing guide for insecure direct object references, where changing an identifier such as a user ID, order number, or file reference may expose someone else’s data.

In plain words
What is it for?
Use it to test URLs, API requests, forms, and other inputs with object identifiers, especially across separate user accounts or organisations.
Why use it?
It helps find missing ownership checks that allow one user or customer account to access another account’s resources.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is - [`_shared/references/elite-chaining-strategy.md`](../_shared/references/elite-chaining-strategy.md) — Exploit chaining methodology and high-payout chain patte.

Good fit Use it to test URLs, API requests, forms, and other inputs with object identifiers, especially across separate user accounts or organisations.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/ShulkwiSEC/bb-huge
agentmods
npx agentmods add skills/shulkwisec/bb-huge/idor-vulnerability-hunting

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 idor-vulnerability-hunting

README.md
[![agentmods](https://agentmods.dev/badge/skills/shulkwisec/bb-huge/idor-vulnerability-hunting/github.svg)](https://agentmods.dev/skills/shulkwisec/bb-huge/idor-vulnerability-hunting)
Your own site
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/idor-vulnerability-hunting"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/idor-vulnerability-hunting/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 idor-vulnerability-hunting

Your own site · 80×15
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/idor-vulnerability-hunting"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/idor-vulnerability-hunting.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 77 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,178 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 original No closer match found 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 $0.00077 $0.03178
Opus 5 $0.00039 $0.01589
Sonnet 5 $0.00015 $0.00636
Haiku 4.5 $0.00008 $0.00318

Measured 7d ago against content hash 1fa7e340a3da, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

idor-vulnerability-hunting 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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/process.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

tools: [burpsuite, ffuf, postman, curl, autorize]
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/curated/idor-vulnerability-hunting/SKILL.md · 308 lines

How it starts

The opening of the file, as written. The whole thing — 308 lines — stays where its author put it; the contents beside it link to each section on GitHub.

IDOR Vulnerability Hunting

When to Use

  • When testing web applications for unauthorized data access via object reference manipulation
  • During bug bounty hunting when you see numeric/sequential IDs in URLs, API calls, or form parameters
  • When API endpoints use predictable identifiers (user_id, order_id, doc_id)
  • When testing multi-tenant applications for cross-tenant data leakage
  • When you find UUID/GUID references that may be predictable or enumerable

When NOT to use: If the application uses cryptographically random tokens AND validates server-side ownership — then move to session management or authentication bypass skills instead.

Prerequisites

  • Burp Suite Pro or Community Edition installed with browser proxy configured
  • Two test accounts with different privilege levels (attacker + victim)
  • curl, httpie, or Postman for API testing
  • ffuf or wfuzz for parameter fuzzing
  • Autorize Burp extension for automated authorization testing
  • Authorization to test the target (bug bounty scope or pentest engagement)

Workflow

Phase 1: Identify Object References

Map every parameter that references objects. These are your attack surface.

# Crawl the target and extract parameters from Burp proxy history
# Look for these patterns in URLs, POST bodies, and headers:

# Numeric sequential IDs (highest priority)
/api/users/1234
/api/orders/5678
/profile?user_id=42
/download?file_id=100

# UUIDs/GUIDs (still testable)
/api/documents/550e8400-e29b-41d4-a716-446655440000

# Encoded references
/api/data?ref=dXNlcl9pZD0xMjM0  # Base64: user_id=1234

# Hashed references
/api/file/5d41402abc4b2a76b9719d911017c592  # MD5 hash

# Composite references
/api/org/15/user/42/report/7
Decision Point 🔀 — What type of reference did you find?
Sequential numeric ID → High chance of IDOR, go to Phase 2 immediately
UUID/GUID → Check if version 1 (time-based, predictable) vs v4 (random)
Base64 encoded → Decode it, modify the decoded value, re-encode
Hashed value → Try common hash patterns (MD5/SHA1 of sequential numbers)
No visible reference → Check JSON response bodies for hidden IDs

Read the full file on GitHub · 308 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 308 lines · 77 tokens per session scan A 1fa7e340a3da

Subscribe to this mod's changes

idor-vulnerability-hunting is a skill published in the GitHub repository ShulkwiSEC/bb-huge (22 stars, last pushed 2mo ago), licensed MIT. It adds 77 tokens to every session and 3,178 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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