broken-access-control

broken-access-control is a skill for Claude Code, Codex from forefy/.context. It costs 31 tokens per session (2,523 once invoked), scanned A, original, MIT.

A security-testing guide for checking whether users can access records that belong to someone else. It replays saved web requests with different user identities and changed object IDs.

In plain words
What is it for?
Use it to test authorization in an application you own or are allowed to assess, using captured requests and controlled test accounts.
Why use it?
It helps find broken access control, including IDOR, where changing an ID in a request exposes another user's data or actions.

Skill for Claude CodeCodex

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

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.

agentmods
npx agentmods add skills/forefy/.context/broken-access-control
Any agent
npx skills add forefy/.context --skill broken-access-control
Clone the repo
git clone --depth 1 https://github.com/forefy/.context

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 broken-access-control

README.md
[![agentmods](https://agentmods.dev/badge/skills/forefy/.context/broken-access-control.svg)](https://agentmods.dev/skills/forefy/.context/broken-access-control)
Your own site
<a href="https://agentmods.dev/skills/forefy/.context/broken-access-control"><img src="https://agentmods.dev/badge/skills/forefy/.context/broken-access-control.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,523 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
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 $0.00031 $0.02523
Opus 5 $0.00015 $0.01262
Sonnet 5 $0.00006 $0.00505
Haiku 4.5 $0.00003 $0.00252

Measured 6d ago against content hash 82d22cb445de, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

broken-access-control 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 6d 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 -sk -o /dev/null -w '%{http_code} %{size_download}b\n' \
skills/applicative-pentest/broken-access-control/SKILL.md · 157 lines

How it starts

The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contents

  • Scope & authorization
  • Methodology (baseline, identity-swap, numeric IDOR)
  • Runnable snippets
  • IDOR numeric-parameter wordlist
  • Thresholds (carry these exactly)
  • Output

Scope & authorization

Only run against an application the user owns or is contractually engaged to test. This is an ACTIVE, aggressive check: it re-sends real requests to the target under different identities and with mutated object-ids, so it creates traffic, may read or touch other users' data, and can trip rate-limits or alerts. Use a staging environment or a maintenance window where you can, keep the identities and object-ids to accounts you control, and stop if you start returning data that clearly belongs to real third parties. If scope is unclear, ask before replaying.

Two things must exist before you start:

  1. A capture of the target's traffic taken as a privileged / higher-role user (from a proxy, HAR export, or your own request log). Each captured request gives you the method, URL, headers, query params, cookies, and body.
  2. At least one second identity to replay under - a lower-privileged user's session, and/or the unauthenticated (no-token, no-cookie) state. An identity is either a cookie (name=value) or a bearer token (Authorization: Bearer ...).

This skill covers authorization replay and numeric IDOR on already-captured requests. It does not fuzz for hidden endpoints, mutate non-numeric/UUID object references, or bypass auth at the token layer (JWT tampering, session fixation) - note those as unrun if the target warrants a deeper pass.

Methodology (run in order; each step is a check with a result state)

  1. Inventory the capture. From the privileged capture, list each request as its parts: method, full URL, headers, query params, cookies, body. These are the units you replay; you never craft new endpoints, only re-send captured ones under new conditions.

  2. Baseline each request as the privileged user. Re-send it exactly as captured and record status_code and response body length. This is the reference every swapped-identity and mutated-id response is compared against, and it confirms the request still works before you draw conclusions from a difference.

Read the full file on GitHub · 157 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. 6d ago First seen · 157 lines · 31 tokens per session scan A 82d22cb445de

Subscribe to this mod's changes

broken-access-control is a skill published in the GitHub repository forefy/.context (144 stars, last pushed yesterday), licensed MIT. It adds 31 tokens to every session and 2,523 once invoked, about $0.0002 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 2026-08-30.

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