Mitm Find Callback

Organization

instavm

mitm-find-callback

Find payment callback and webhook vulnerabilities. Use when user asks about payment security, callback tampering, hash validation, or transaction manipulation.

Overview

Publisher	instavm
Repository	`security-skills`
Skill name	`mitm-find-callback`
Stars	88
Forks	12
Bundled files	Instructions only
Links	Skill source Repository Homepage

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
Self-contained
Everything the model needs lives in the instructions — no extra files to sync.
Open source
Published by instavm on GitHub. Read the source before you install it.

Installation

Install the Mitm Find Callback AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/instavm/security-skills/tree/main/skills/mitm-find-callback
Enable the skill in any chat where you want it available.

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/instavm/security-skills.git /tmp/security-skills
mkdir -p .claude/skills
cp -r /tmp/security-skills/skills/mitm-find-callback .claude/skills/mitm-find-callback

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Mitm Find Callback in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Mitm Find Callback on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Mitm Find Callback is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Find Payment Callback Vulnerabilities

Analyze the mitmproxy dump (log.txt) for payment callback issues for: $ARGUMENTS

Requires: log.txt in the current directory. If it's missing, capture traffic first:

bash
mitmdump --set flow_detail=3 2>&1 | tee log.txt

Vulnerability Types

1. Hash/Signature Not Validated

Callback accepts any hash value
Hash parameter present but not verified
Can change status without valid signature

2. Status Manipulation

Change status=failed to status=success
Modify unmappedstatus parameter
Tamper with transaction result

3. Amount Manipulation

Modify amount before callback
Pay less, get full order
Decimal manipulation

4. Signature Collision

Same signature works for payment and refund
Parameter reordering gives same hash
Missing fields in signature calculation

5. Checksum Generation Exposed

API returns checksum even on error
Can generate arbitrary checksums
Checksum algorithm is weak (MD5/SHA1 without salt)

Testing Approach

bash
# Test callback with modified status
curl -X POST "https://merchant.com/payment/callback" \
  -d "txnid=12345&status=success&hash=original_hash"

# Test with invalid hash
curl -X POST "https://merchant.com/payment/callback" \
  -d "txnid=12345&status=success&hash=aaaa"

Red Flags in Traffic

Callback URLs with all params in request
Hash visible in client-side code
Salt/secret in JavaScript
Error responses containing valid checksums

Output Format

For each finding:

Callback URL: Vulnerable endpoint
Issue: What can be manipulated
Parameters: Affected fields
Test: How to exploit
Impact: Free orders, refunds, etc.
Fix: Proper server-side validation

Frequently asked questions

What does the Mitm Find Callback AI skill do?

Find payment callback and webhook vulnerabilities. Use when user asks about payment security, callback tampering, hash validation, or transaction manipulation.

Why use Mitm Find Callback on TypingMind?

Because you install it once and use it with any model. Mitm Find Callback is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Mitm Find Callback in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/instavm/security-skills/tree/main/skills/mitm-find-callback. TypingMind reads its SKILL.md and installs it as a skill you can enable per chat.

Which AI models can use Mitm Find Callback?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Mitm Find Callback?

As many as you like. As long as a model supports skills, you can use Mitm Find Callback with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Mitm Find Callback AI skill free?

It is published on GitHub by instavm. Check the repository for licensing terms. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

Find Payment Callback Vulnerabilities

Vulnerability Types

1. Hash/Signature Not Validated

2. Status Manipulation

3. Amount Manipulation

4. Signature Collision

5. Checksum Generation Exposed

Testing Approach

Red Flags in Traffic

Output Format

Frequently asked questions

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