Academy for LoRaWAN®

Deploying any kind of network that transmits data imposes a security risk. LoRaWAN networks are no different. Even if you follow the LoRaWAN specifications and implement the security layers, you still face the risk of the device being attacked physically. People with malicious intent can manipulate sensors, flash new firmware onto a device, or hack their way in to derive the keys.

To secure the end devices deployed in the field, crypto chips can be used. Crypto chips, commonly known as secure elements can securely store keys and efficiently encrypt and decrypt data.

Sample Cryptochip Location

Potential Threats

Before we dive into the details of crypto chips, however, let’s take a step back and look at two vulnerabilities that IoT devices face when someone gains physical access to them.

Compromising LoRaWAN Keys

End devices on LoRaWAN networks contain a number of hardware components such as the MCU, peripherals, and the radio module. Communication among components is unencrypted and the data transfer happens via an interface such as UART, SPI, or I²C. When attackers gain access to the physical device, they can use special hardware to monitor the onboard communication.

Because session keys are derived from roots key and stored in local memory, and because the root keys are also stored in memory, albeit usually internal to the MCU, having physical access to a device allows for the possibility of reading the root and session keys from a memory location. If a session key is “read-only”, that device's session is compromised. It is only when a root key is read that an attacker can fully impersonate a device and impersonate the legitimate end device by using the same credentials and security keys.

Researchers^[1] have proven there is a theoretical feasibility of such an attack, and derived the keys from a specific LoRaWAN end device by monitoring the line of communication between the MCU and the LoRaWAN module with an FTDI chip. Every time the device reset, the keys were changed between the components and the keys could be impersonated.

Overwriting Device Firmware

Another potential threat, which can occur as either a physical or digital attack, is the flashing of new firmware onto a device. A hacker can connect to the device physically to upload new firmware, or by initiating a firmware update over-the-air. New firmware can make the device unusable. Worse, new software can be installed that simply requests the desired keys.