A phishing-led intrusion chain is an attack path that starts with a deceptive email, message, or file delivery and uses that first interaction to gain access. The goal is usually to trick the victim into clicking a link, opening an attachment, entering credentials, or approving a login prompt. Once the attacker has that foothold, they can move into malware delivery, mailbox takeover, internal reconnaissance, or further credential theft.
This matters because phishing is often the cheapest and most reliable entry point in cyber attacks. It bypasses many perimeter defenses by targeting people and identity systems instead of software bugs. Defenders look for this chain with email filtering, domain authentication, attachment sandboxing, phishing-resistant MFA, and post-click detection that flags unusual script execution, browser activity, or logins after a message is opened. Breaking any link in the chain can stop the intrusion before it spreads.