upload-insecure-files

upload-insecure-files is a skill for Claude Code, Codex from DorianGallo/hack-skills-local. It costs 37 tokens per session (4,565 once invoked), scanned C, a copy of upload-insecure-files, MIT.

A security guide to file-upload handling, including how uploaded files are checked, stored, processed, previewed, and served.

In plain words
What is it for?
It is for authorized testing of avatars, documents, media, archives, import features, and upload-related server behavior.
Why use it?
It helps find validation mistakes, unsafe storage paths, overwrites, parser problems, and chains that turn an upload into script execution or other impact.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It is for authorized testing of avatars, documents, media, archives, import features, and upload-related server behavior.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/doriangallo/hack-skills-local/upload-insecure-files
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 DorianGallo/hack-skills-local --skill upload-insecure-files
Clone the repo
git clone --depth 1 https://github.com/DorianGallo/hack-skills-local

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/doriangallo/hack-skills-local/upload-insecure-files/github.svg)](https://agentmods.dev/skills/doriangallo/hack-skills-local/upload-insecure-files)
Your own site
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/upload-insecure-files"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/upload-insecure-files/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 upload-insecure-files

Your own site · 80×15
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/upload-insecure-files"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/upload-insecure-files.svg" alt="Reviewed on agentmods" width="80" 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 4,565 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 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 $0.00037 $0.04565
Opus 5 $0.00018 $0.02282
Sonnet 5 $0.00007 $0.00913
Haiku 4.5 $0.00004 $0.00456

Measured 7d ago against content hash 543343d08d49, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, 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 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.

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

100% identical to upload-insecure-files — 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.

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

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 543 lines · 37 tokens per session scan C 543343d08d49

Subscribe to this mod's changes

upload-insecure-files is a skill published in the GitHub repository DorianGallo/hack-skills-local (5 stars, last pushed 3mo ago), licensed MIT. It adds 37 tokens to every session and 4,565 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 100% identical to upload-insecure-files, differing in 0 lines, and is treated as a copy.

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