csrf-cross-site-request-forgery

csrf-cross-site-request-forgery is a skill for Claude Code, Codex from miru-zero/zero-brain. It costs 44 tokens per session (4,217 once invoked), scanned D, a copy of csrf-cross-site-request-forgery, MIT.

A testing guide for cross-site request forgery (CSRF), an attack that tricks a signed-in user's browser into changing data on a website.

In plain words
What is it for?
Use it to review state-changing web requests, session-cookie behavior, SameSite settings, JSON requests, login flows, and OAuth state checks.
Why use it?
It helps find missing or incorrectly implemented protections on actions such as changing passwords, email addresses, or user roles.

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 Attack: Set PROFILE_ID to ../../admin/dangerous-action.

Good fit Use it to review state-changing web requests, session-cookie behavior, SameSite settings, JSON requests, login flows, and OAuth state checks.

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/miru-zero/zero-brain
agentmods
npx agentmods add skills/miru-zero/zero-brain/csrf-cross-site-request-forgery

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 csrf-cross-site-request-forgery

README.md
[![agentmods](https://agentmods.dev/badge/skills/miru-zero/zero-brain/csrf-cross-site-request-forgery.svg)](https://agentmods.dev/skills/miru-zero/zero-brain/csrf-cross-site-request-forgery)
Your own site
<a href="https://agentmods.dev/skills/miru-zero/zero-brain/csrf-cross-site-request-forgery"><img src="https://agentmods.dev/badge/skills/miru-zero/zero-brain/csrf-cross-site-request-forgery.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,217 The whole file, excluding the scripts and references it only reads on demand.
Security scan D 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 97% copy Near-identical to another mod 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 $0.00044 $0.04217
Opus 5 $0.00022 $0.02108
Sonnet 5 $0.00009 $0.00843
Haiku 4.5 $0.00004 $0.00422

Measured 7d ago against content hash 9ae8d96a8162, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade D, and why

csrf-cross-site-request-forgery scanned grade D with 2 findings 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.

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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- If server accepts GET for state-changing endpoint: -->

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

fetch('https://target.com/api/v1/change-email', { method: 'POST',
Origin

This is a copy

97% identical to csrf-cross-site-request-forgery — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/csrf-cross-site-request-forgery/SKILL.md · 527 lines

How it starts

The opening of the file, as written. The whole thing — 527 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: CSRF — Cross-Site Request Forgery — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert CSRF techniques. Covers modern bypass vectors (SameSite gaps, custom header flaws, tokenless bypass patterns), JSON CSRF, multipart CSRF, chaining with XSS. Base models often present only basic CSRF without covering SameSite edge cases and common broken token implementations.

Also load:


1. CORE CONCEPT

CSRF exploits a victim's active session to perform state-changing requests from the attacker's origin.

Required conditions:

  1. Victim is authenticated (active session cookie)
  2. Server identifies session via cookie only (no secondary check)
  3. Attacker can predict/construct the valid request
  4. Cookie is sent cross-origin (SameSite=None or legacy behavior)

2. FINDING CSRF TARGETS

High-value state-changing endpoints:

- Password change         ← account takeover
- Email change            ← account takeover
- Add admin / change role ← privilege escalation
- Bank/payment transfer   ← financial impact
- OAuth app authorization ← hijack oauth flow
- Account deletion
- Two-factor auth disable  
- SSH key / API key addition
- Webhook configuration
- Profile/contact info update

3. TOKEN BYPASS TECHNIQUES

No Token Present

Simplest case — form simply lacks CSRF token. Check if POST /change-email has any token. If not → trivially exploitable.

Token Not Validated (most common finding!)

Token exists in request but is never verified server-side:

Remove the _csrf_token parameter entirely → does request still succeed?
→ YES → trivial bypass

Token Tied to Session but Not to User

Step 1: Log in as UserA → obtain valid CSRF token
Step 2: Log in as UserB in other browser → obtain UserB CSRF token  
Step 3: Use UserB's CSRF token in UserA's session (attacker controls UserB)
→ If server validates token exists but doesn't check if it belongs to the session → bypass

Read the full file on GitHub · 527 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. 7d ago First seen · 527 lines · 44 tokens per session scan D 9ae8d96a8162

Subscribe to this mod's changes

csrf-cross-site-request-forgery is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 20d ago), licensed MIT. It adds 44 tokens to every session and 4,217 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it D with 2 findings (hidden instructions, sends data to an external url). It is 97% identical to csrf-cross-site-request-forgery, differing in 4 lines, and is treated as a copy.

Related

Other skills, from other repositories

research-engineer

An uncompromising Academic Research Engineer. Operates with absolute scientific rigor, objective criticism, and zero flair. Focuses on theoretical correctness, formal verification, and optimal implementation across any required technology.

davila7/claude-code-templates · 43 tokens

tika-eval-compare

Compare extracts from two Tika builds over a corpus to detect regressions in content, encoding, exceptions, and embedded-document handling. Use for "compare before/after extracts", "eval this change against the corpus".

apache/tika · 50 tokens

neuron-evaluation-engineer

Create and run AI evaluations with datasets, assertions, and output drivers in Neuron AI. Use this skill whenever the user mentions evaluation, testing AI systems, creating evaluators, dataset-driven testing, assertion-based validation, or wants to measure AI system performance. Also trigger for tasks involving…

neuron-core/neuron-ai · 77 tokens

jetson-validate-image

Use after jetson-flash-image to run static BSP checks, on-target smoke/regression tests on a flashed DUT, or both. Not for build or flash steps. Triggers: validate bsp, on-target validation.

NVIDIA/skills · 50 tokens

atmos-validation

Validate Atmos projects, components, arbitrary JSON Schema inputs, EditorConfig, and GitHub Actions; use affected-file selection and native CI annotations.

cloudposse/atmos · 31 tokens

skill-benchmark

Benchmark AI skill effectiveness by measuring implementation quality against legacy constraints.

HoangNguyen0403/agent-skills-standard · 16 tokens