I Boot when U-Boot presented at Bsidesamsterdam 2017

by Bernardo Maia Rodrigues, Vincent Ruijter,

Summary : Personal computer systems are now considerably more secure than embedded devices. Trusted Platform Module (TPM) and secure boot are readily available and even default in a lot of new desktop computers and laptops. Numerous small office and consumer devices, including routers and smart televisions, however, are lacking even the most basic security features. In this talk we will demonstrate and describe the inner-workings of a custom developed (Fully Weaponised IoT Cyber™) bootkit, which gains persistence on U-Boot based embedded devices, at a lower level than even the firmware. Firmware updates and factory resets usually do not interfere with the bootloader, as a small problem could render the device unusable for an end-user: the bootkit will therefore remain present. including a properly functioning killswitch and a multi-boot like technique, it is possible to switch between a regular and a backdoored image to thwart detection. Enterprises and ISPs must take this additional attack surface into account, and put effort into detecting and responding to this threat. Well-known security researchers have long advocated for easier ways to verify and demonstrate the integrity of hardware, but this comes at a price that vendors are not willing to pay for security. Recently however, regulatory bodies have started to enforce vendors to lock-down their wireless devices, in order to prevent them from operating outside of their certified frequencies. But these 'vendor lock-downs' are not sufficient to increase the device security, as we will demonstrate, it's just a minor inconvenience.