a tiny surveillance chip, not much bigger than a grain of rice, has been found hidden in the servers used by nearly 30 American companies, including Apple and Amazon

The malicious chips, which were not part of the original server motherboards designed by the U.S-based company Super Micro, had been inserted during the manufacturing process in China.

they were capable of doing two very important things: telling the device to communicate with one of several anonymous computers elsewhere on the internet that were loaded with more complex code; and preparing the device’s operating system to accept this new code

https://thehackernews.com/2018/10/china-spying-server-chips.html