The United States Computer Emergency Readiness Team (US-CERT) publishes recommendations. A MITM attack occurs when a third party inserts itself between the communications of a client and a server. MITM attacks as a general class are not new. Classic MITM attacks (e.g., ARP Spoofing) focus on redirecting network communications. By definition, network infrastructure under attacker control is vulnerable to MITM. However, as technology evolves, new methods for performing MITM attacks evolve as well.
Read more on how to mitigate MITM attacks here - https://www.us-cert.gov/ncas/alerts/TA15-120A