Use secure applications and protocols
Certain protocols dating back to the start of the internet did not take account of the need to respect the confidentiality, integrity and availability (CIA) of transmitted information (e.g. by using non-hidden passwords or reproducing a transaction that was supposed to be unique).
Moving to more secure versions of the main protocols (e.g. SFTP/FTPS and HTTPS) allows major security loopholes to be closed.