has been observed using TCP port 25 without using SMTP to leverage an open port for secure command and control communications.(Citation: CISA WellMail July 2020)
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request. ### Instruction: List the MITRE techniques contained in the text. ### Input: has been observed using TCP port 25 without using SMTP to leverage an open port for secure command and control communications.(Citation: CISA WellMail July 2020) ### Response: T1571.