An intrusion vector is the path attackers use to enter a network, system, or cloud environment. Common vectors include stolen credentials, phishing emails, exposed remote access services, vulnerable public-facing applications, and misconfigured third-party connections.
Knowing the intrusion vector matters because it reveals where defenses failed and what to harden first. In real incidents, investigators look for the initial access method before they can assess scope, persistence, or data theft. Defenders use this information to reduce risk with multi-factor authentication, patching, access reviews, email filtering, network segmentation, and logging that can spot abnormal logins or exploit attempts early.