upload-insecure-files

upload-insecure-files is a skill for Claude Code, Codex from miru-zero/zero-brain. It costs 37 tokens per session (4,586 once invoked), scanned C, a copy of upload-insecure-files, MIT.

A security testing guide for file-upload features, including validation, storage, previews, overwriting, and processing behavior.

In plain words
What is it for?
Use it to assess uploads of documents, images, archives, and other files, including possible chains to code execution or other web vulnerabilities.
Why use it?
It helps find cases where an uploaded file is accepted, exposed, processed unsafely, or used to affect another user's data or server.

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/miru-zero/zero-brain/upload-insecure-files
Any agent
npx skills add miru-zero/zero-brain --skill upload-insecure-files
Clone the repo
git clone --depth 1 https://github.com/miru-zero/zero-brain

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 upload-insecure-files

README.md
[![agentmods](https://agentmods.dev/badge/skills/miru-zero/zero-brain/upload-insecure-files.svg)](https://agentmods.dev/skills/miru-zero/zero-brain/upload-insecure-files)
Your own site
<a href="https://agentmods.dev/skills/miru-zero/zero-brain/upload-insecure-files"><img src="https://agentmods.dev/badge/skills/miru-zero/zero-brain/upload-insecure-files.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,586 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. Scan, not verified.
Origin 92% 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 $0.00037 $0.04586
Opus 5 $0.00018 $0.02293
Sonnet 5 $0.00007 $0.00917
Haiku 4.5 $0.00004 $0.00459

Measured 2d ago against content hash e3951ef5b1bc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade C, and why

upload-insecure-files scanned grade C 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 2d 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.

Cloud metadata endpointhighServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

http://169.254.169.254/latest/meta-data/iam/security-credentials/
Origin

This is a copy

92% identical to upload-insecure-files — 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/upload-insecure-files/SKILL.md · 543 lines

How it starts

The opening of the file, as written. The whole thing — 543 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Upload Insecure Files — Validation Bypass, Storage Abuse, and Processing Chains

AI LOAD INSTRUCTION: Expert file upload attack playbook. Use when the target accepts files, imports, avatars, media, documents, or archives and you need the full workflow: validation bypass, storage path abuse, post-upload access, parser exploitation, multi-tenant overwrite, and chaining into XSS, XXE, CMDi, traversal, or business logic impact. For web server parsing vulnerabilities, PUT method exploitation, and specific CVEs (WebLogic, Flink, Tomcat), load the companion SCENARIOS.md.

Extended Scenarios

Also load SCENARIOS.md when you need:

  • IIS parsing vulnerabilities — x.asp/ directory parsing, ; semicolon truncation (shell.asp;.jpg)
  • Nginx parsing misconfiguration — avatar.jpg/.php with cgi.fix_pathinfo=1
  • Apache parsing — multiple extensions, AddHandler, CVE-2017-15715 \n (0x0A) bypass
  • PUT method exploitation — IIS WebDAV PUT+COPY, Tomcat CVE-2017-12615 readonly + .jsp/ bypass
  • WebLogic CVE-2018-2894 arbitrary file upload via Web Service Test Page
  • Apache Flink CVE-2020-17518 file upload with path traversal
  • Upload + parsing vulnerability chain — EXIF PHP code + Nginx /.php path info
  • Full extension bypass reference table (PHP/ASP/JSP alternatives, case variations, null bytes)

Use this file as the deep upload workflow reference. Also load:

Read the full file on GitHub · 543 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. 2d ago First seen · 543 lines · 37 tokens per session scan C e3951ef5b1bc

Subscribe to this mod's changes

upload-insecure-files is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 19d ago), licensed MIT. It adds 37 tokens to every session and 4,586 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (cloud metadata endpoint). It is 92% identical to upload-insecure-files, differing in 4 lines, and is treated as a copy.

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