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Introduction:
The proliferation of accessible, powerful microcontrollers like the Raspberry Pi RP2040 has democratized hardware innovation, but it also opens a new vector for cyber-physical attacks. What begins as a fun, personal electronics project can be repurposed into a stealthy bad USB device, a wireless keylogger, or a physical entry point into a secure network. Understanding the underlying technology is the first step in defending against the threats it could be engineered to pose.
Learning Objectives:
- Understand the offensive security capabilities of seemingly benign microcontroller-based devices.
- Learn to identify and mitigate threats from rogue Human Interface Device (HID) attacks.
- Develop strategies for hardening IT policies against unauthorized physical hardware.
You Should Know:
1. The RP2040 as a Stealth Attack Platform
The Raspberry Pi RP2040, while a powerhouse for makers, is also a capable chip that can be programmed to emulate USB devices. When combined with a compact form factor like a badge and powered by a long-lasting CR2032 cell, it becomes a persistent, concealable threat. An attacker can program it to pose as a keyboard, automatically executing malicious commands on any computer it’s plugged into.
Step‑by‑step guide explaining what this does and how to use it.
The Threat: A device like the badge can be pre-loaded with a script that runs the instant it’s plugged into a USB port. It can open a terminal, download a payload from the internet, and establish a reverse shell, giving an attacker remote control.
Verification & Demonstration (Using a Pico):
While the badge is a custom PCB, the same RP2040 chip powers the Raspberry Pi Pico. You can test this concept with a Pico loaded with CircuitPython and the following code snippet saved as code.py:
import time import usb_hid from adafruit_hid.keyboard import Keyboard from adafruit_hid.keycode import Keycode Wait a moment to ensure the device is recognized time.sleep(2) keyboard = Keyboard(usb_hid.devices) Open a terminal (Ctrl+Alt+T on Linux) keyboard.press(Keycode.CONTROL, Keycode.ALT, Keycode.T) keyboard.release_all() time.sleep(0.5) Type a command keyboard.send(Keycode.W, Keycode.H, Keycode.O, Keycode.A, Keycode.M, Keycode.I) keyboard.send(Keycode.ENTER)
This simple script will, upon plugging in, open a terminal and type “WHOAMI”. A malicious version would run far more damaging commands.
2. Firmware Manipulation and Supply Chain Risks
The post mentions using ChatGPT to generate code for light effects. This practice, while efficient, introduces a supply chain risk. An attacker could compromise a public code library or provide a malicious “helpful” script that includes a hidden payload, which is then blindly flashed onto the device.
Step‑by‑step guide explaining what this does and how to use it.
The Threat: The firmware running on the device is the core of its functionality. If an attacker can trick a developer into using tampered-with code, they can gain a foothold. The badge’s USB-C port is the perfect conduit for this malicious firmware to be deployed.
Mitigation Steps for Developers:
- Code Auditing: Never deploy code, especially from AI or unverified sources, without a line-by-line review.
- Checksum Verification: Always verify the integrity of downloaded toolchains and libraries by checking their SHA-256 hashes.
Linux/macOS: `sha256sum downloaded_file.uf2`
Windows (PowerShell): `Get-FileHash .\downloaded_file.uf2 -Algorithm SHA256`
- Secure Development Environment: Use isolated virtual machines or containers for initial testing of new code and libraries.
3. Power Persistence and Physical Infiltration
The use of a TI TPS61099 boost converter is a masterclass in power efficiency, allowing the badge to run for a very long time on a single coin cell. For an attacker, this means a device can be planted in an office and remain active for weeks or months, waiting to establish a Bluetooth or Wi-Fi connection or to execute its payload when triggered.
Step‑by‑step guide explaining what this does and how to use it.
The Threat: A device that requires no external power and is easily concealed can be left behind after a meeting or social engineering visit. It could be programmed to beacon out or await a specific signal.
Defensive IT Policy Actions:
- Device Control Policies: Implement Group Policy (Windows) or configuration profiles (macOS) to block unauthorized USB devices.
Windows GPO: Navigate toComputer Configuration > Administrative Templates > System > Device Installation > Device Installation Restrictions. - Physical Security: Train staff to be wary of unauthorized hardware. Implement clean desk policies and regular physical sweeps of sensitive areas.
- Network Segmentation: Ensure guest networks are fully isolated from corporate networks to limit the lateral movement of any implanted device.
4. Social Engineering Through “Innocent” Hardware
The project is described as “a small thing that made me smile,” which is precisely the social engineering hook. A custom, visually appealing badge is a conversation starter and can be used to build trust before an attacker plugs it into a target system “just to show the cool lights.”
Step‑by‑step guide explaining what this does and how to use it.
The Threat: The human element is often the weakest link in security. A clever attacker uses curiosity and social norms to bypass technical defenses.
Security Awareness Training:
- Principle of Least Privilege: No user should have local admin rights, which can prevent many payloads from executing successfully.
- Phishing and Social Engineering Drills: Include modules on physical social engineering, teaching employees to never plug unknown hardware into their computers, regardless of the source.
- Clear Reporting Procedures: Employees must know who to contact if they are presented with such a scenario.
5. Detecting and Analyzing Suspicious USB Devices
System administrators need tools to monitor and control what is connected to their network. Both Linux and Windows provide native capabilities to inventory connected hardware.
Step‑by‑step guide explaining what this does and how to use it.
The Goal: Gain visibility into all USB devices connected to endpoints to identify unauthorized hardware.
Command-Line Inventory Checks:
Linux: The `lsusb` command lists all USB buses and the devices connected to them. For more detail, use usb-devices.
$ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 046d:c08b Logitech, Inc. G502 SE HERO Gaming Mouse An unknown device would appear here with its Vendor and Product ID.
Windows (PowerShell): Use the `Get-PnpDevice` cmdlet to filter for USB devices.
Get-PnpDevice -Class USB | Format-Table FriendlyName, Status, InstanceId
Centralized Monitoring: Use an Endpoint Detection and Response (EDR) solution to collect this data from all managed machines and alert on new or unrecognized device types.
What Undercode Say:
- The line between a benign tech toy and a malicious tool is defined solely by the intent and code of the user. The hardware is neutral.
- Modern cybersecurity defense must extend beyond the network perimeter to include the physical realm and the software supply chain, no matter how small the source.
Analysis:
The post by Petr Dvořák is a brilliant example of the maker spirit, but from a security perspective, it’s a blueprint for a potentially undetectable threat. The core components—the low-power RP2040, the highly efficient power converter, and the use of AI-assisted coding—are all dual-use technologies. The security community’s focus has often been on software-based attacks, but this highlights the escalating risk of hardware-based, physically-present threats. The device’s innocuous appearance is its greatest weapon, exploiting trust and curiosity. Defending against this requires a paradigm shift towards zero-trust principles applied to physical hardware, stringent developer hygiene regarding third-party code, and continuous user education that makes every employee a vigilant last line of defense.
Prediction:
In the next 2-3 years, we will see a significant rise in incidents stemming from weaponized DIY hardware and “gifted” or “lost” malicious devices. As AI code generation becomes more prevalent, supply chain attacks via poisoned AI suggestions will become a standard part of the attacker’s toolkit, targeting IoT and maker projects as a stepping stone into corporate environments. Penetration testers will routinely include custom, innocuous-looking hardware like this badge in their physical security assessments, forcing organizations to adopt stricter device control and monitoring policies.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Petr Dvorak – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
