PoET implementation will depend on that of SGX. SGX is a set of instructions which allows application to run in sectioned-off areas of memory called enclaves. This aims to protect sensitive data and code from disclosure or tampering, both when stored and at runtime. Unfortunately, since Intel first introduced SGX in 2013, several weaknesses have been found in its design.
https://www.theregister.co.uk/2016/02/01/sgx_secure_until_you_look_at_the_detail/