Reverse engineering UEFI firmware updater

[…]I wanted to reverse engineer the UEFI code running on my own laptop (a Lenovo Y520-15IKBN). To do this, I will first need to obtain the firmware. This should be extractable from a firmware update, so I downloaded the firmware updater from the Lenovo support site.[…]I extracted the contents of the flash ROM with UEFIExtract in the new_engine branch of UEFITool. This resulted in a folder containing over 300 PE images. One of them sounded interesting: SecureBackDoorPeim, but I think this blog post is long enough, so it may be the topic of another post.[…]