MitM

MITM stands for Man-in-the-Middle attack, a security breach in which an attacker secretly intercepts and potentially alters the communications between two parties who believe they are directly communicating with each other. The goal is to gain access to information, modify data, or impersonate one of the endpoints.

In a MITM scenario, the attacker places themselves on the communication path, enabling eavesdropping, data tampering, or impersonation. Common vectors include compromised or insecure networks, spoofed DNS responses, or local network manipulations such as ARP spoofing or fake access points. Attacks can be passive, observing traffic, or active, where content is modified, requests or responses are injected, or messages are replayed.

MITM can result in several harms, including breach of confidentiality, loss of data integrity, and invalid authentication. Sensitive information such as credentials, financial data, or personal information may be exposed, and communications may be altered without the participants’ knowledge.

Defenses focus on ensuring confidentiality, integrity, and authenticity. Strong encryption and correct certificate validation are central, particularly TLS with proper verification, mutual TLS, and, in some cases, certificate pinning. Additional protections include HTTP Strict Transport Security (HSTS), the use of virtual private networks (VPNs), secure DNS mechanisms (such as DNSSEC or DNS over HTTPS), and comprehensive network monitoring.

Detection and prevention rely on keeping software up to date and using trusted networks. Users may encounter certificate warnings or unexpected TLS errors, while administrators employ intrusion detection, anomaly detection, and integrity monitoring to identify abnormal MITM activity.