Thrangrycat

To perform this validation each time the device resets, Cisco developed a separate, special-purpose hardware device, known as the Trust Anchor module (TAm), as a root of trust for the secure boot process. After initial power-on, the FPGA loads an unencrypted bitstream implementing the hardware Trust Anchor to provide root of trust functionality from a dedicated Serial Peripheral Interface (SPI) flash chip. Yes, this vulnerability is specific to Cisco’s proprietary FPGA-based hardware Trust Anchor implementations.

Source: thrangrycat.com