Question to all hardware experts out there. Software backdoor - sure possible when you don't have source code for your operating system. Hardware backdoor with physical access - possible. But is hardware backdoor without physical access possible? Suppose I buy lenovo or whatever, I write random data to memory and disks 100 times, I install an open-source operating system and use only open-source drivers. Is backdoor possible? What if I also replace Network Interface Controller with one I trust?