hunt-cache-poison

hunt-cache-poison is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 123 tokens per session (5,611 once invoked), scanned B, original, MIT.

A security testing guide for finding cache-poisoning weaknesses, where an attacker causes a shared web cache to store and serve a harmful or incorrect response.

In plain words
What is it for?
Use it when assessing CDNs, cached web applications, authentication pages, e-commerce flows, asset delivery, or other systems that share cached responses.
Why use it?
It helps security testers look for flaws that can affect many visitors at once, including poisoned pages, scripts, authentication responses, or downloads.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it when assessing CDNs, cached web applications, authentication pages, e-commerce flows, asset delivery, or other systems that share cached responses.

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Install with agentmods
npx agentmods add skills/uphiago/recon-skills/hunt-cache-poison
About the project

Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.

uphiago/recon-skills · 1,254 stars · on GitHub · hiago.sh

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.

Any agent
npx skills add uphiago/recon-skills --skill hunt-cache-poison
Clone the repo
git clone --depth 1 https://github.com/uphiago/recon-skills

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 hunt-cache-poison

README.md
[![agentmods](https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-cache-poison/github.svg)](https://agentmods.dev/skills/uphiago/recon-skills/hunt-cache-poison)
Your own site
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-cache-poison"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-cache-poison/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 hunt-cache-poison

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-cache-poison"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-cache-poison.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 123 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,611 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Data Exfiltration · line 317
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
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 $0.00123 $0.05611
Opus 5 $0.00062 $0.02805
Sonnet 5 $0.00025 $0.01122
Haiku 4.5 $0.00012 $0.00561

Measured 8d ago against content hash 012760ff0bb5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade B, and why

hunt-cache-poison scanned grade B 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 8d 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.

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.

curl --max-time 30 --connect-timeout 10 -s -X GET "https://httpbin.org/get" -d "test=body" 2>/dev/null | grep -q "test" && echo "PASS: GET with body supported" || echo "(httpbin may be down)"

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl --max-time 30 --connect-timeout 10 -s -I "https://target.com/page" | grep -i "age\|x-cache\|cf-cache"
redteam/hunt-cache-poison/SKILL.md · 342 lines

How it starts

The opening of the file, as written. The whole thing — 342 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.


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
  • Servers that reflect unvalidated headers into responses (Host, X-Forwarded-Host, X-Original-URL)

Read the full file on GitHub · 342 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. 8d ago First seen · 342 lines · 123 tokens per session scan B 012760ff0bb5

Subscribe to this mod's changes

hunt-cache-poison is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 123 tokens to every session and 5,611 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, 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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