IoT Pentesting Fundamentals

IoT (Internet of Things) security testing spans hardware, firmware, wireless, network, mobile, and cloud: a single device usually touches all of them. Effective testing means mapping that whole ecosystem rather than treating the device as one black box.

The IoT attack surface

Layer	What to look at
Hardware	Debug ports (UART, JTAG, SWD), exposed flash chips, test pads
Firmware	Hardcoded credentials, keys, outdated components, weak update mechanism
Wireless	Wi-Fi, BLE, Zigbee, Z-Wave, LoRa, pairing and encryption weaknesses
Network	Open services, plaintext protocols, weak TLS, local APIs
Mobile app	Companion app secrets, insecure storage, weak auth to the device/cloud
Cloud	Device-to-cloud APIs, account/tenant isolation, MQTT topic access control

A practical methodology

1. Recon the ecosystem: device, app, cloud endpoints, and the protocols between them.
2. Extract firmware: from an update file, the vendor site, or directly from flash; then unpack with binwalk and review the filesystem.
3. Analyse firmware: search for credentials, keys, and certificates; identify the OS and outdated packages.
4. Test the network services: enumerate open ports, inspect protocols, attempt auth bypass and command injection on local APIs.
5. Examine wireless: capture and analyse pairing; check for unencrypted or replayable traffic.
6. Assess the mobile + cloud path: how the app authenticates to the device and the backend; test for IDOR and weak tenant isolation.

Common findings

• Hardcoded or default credentials in firmware
• Unauthenticated UART/serial console giving a root shell
• Unsigned firmware updates (no integrity / authenticity checks)
• Plaintext device-to-cloud communication
• Companion app trusting the device or backend implicitly

Starter tooling

• Firmware: binwalk, firmware-mod-kit, firmwalker, Ghidra
• Hardware: logic analyzer, USB-UART adapter, Bus Pirate, flashrom
• Wireless: Ubertooth (BLE), HackRF, Wireshark
• Network: nmap, mosquitto clients (MQTT), Burp Suite

Always test only devices you own or are explicitly authorised to assess.