Under The Door

R3zk0n · October 2, 2025

Exploitation   Security
Contents

    Based off: https://www.youtube.com/watch?v=T2rxlzdqu1g

    Create using this: https://www.youtube.com/watch?v=TCalV8HqnIM - Copper Wire

    Under the Door (UDT) Tool

    An Under the Door (UDT) tool is a device used by security professionals to exploit lever-style door handles from the outside of a locked door. The tool is slid under the door, then manipulated to hook onto the door handle and pull it down, unlocking the door.

    Steps to Use an Under the Door Tool:

    1. Insert the Tool: Slide the UDT tool under the door, ensuring the string or wire end goes under first.

    2. Maneuver the Tool: Maneuver the tool so that the hook or loop end reaches the door handle.

    3. Hook the Door Handle: Using the string or wire, manipulate the hook or loop to catch the handle of the door.

    4. Pull the Handle: Once the handle is caught, pull the string or wire, causing the door handle to turn and open the door.

    Considerations:

    • This method only works on lever-style door handles that can be operated simply by pulling down.
    • As with all physical security testing techniques, it should be used legally and with permission.

    DIY Under the Door Tool

    Creating an Under the Door tool from basic materials is straightforward. Here’s how you can make one from a metal coat hanger, a shoestring, and some duct tape:

    Materials Needed:

    • Metal coat hanger
    • Shoestring
    • Duct tape

    Steps:

    1. Prepare the Coat Hanger: Unwind the metal coat hanger and straighten it out as much as possible. Leave a small hook at one end.

    2. Attach the Shoestring: Tie one end of the shoestring securely to the hook end of the coat hanger.

    3. Reinforce the Connection: Use duct tape to reinforce the connection between the shoestring and the coat hanger. This will help prevent the shoestring from detaching under pressure.

    4. Manipulate the Hanger: Bend the other end of the coat hanger (the end without the shoestring) into a loop or hook that can catch a door handle.

    With this makeshift tool, you can use the same steps as with a professional UDT tool to hook the door handle and pull it down, opening the door.

    Tools Required

    • Metal Coat Hanger: This forms the main body of the tool. It should be sturdy and flexible enough to slide under a door and hook a door handle.

    • Shoestring: This is used to pull the handle down once the tool is in place. It needs to be strong enough to withstand the pressure.

    • Duct Tape: Used to reinforce the connection between the shoestring and the coat hanger.

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