backdoor

What is a backdoor — how attackers keep their way in, and how to spot it

A backdoor is a hidden entry point planted so an attacker can return while bypassing normal authentication. It usually follows an initial breach and turns one intrusion into ongoing access; it can also arrive inside a poisoned dependency. What separates it from legitimate remote maintenance is whether someone authorised it, knows about it, and can see it in the logs. Defense: least privilege, integrity monitoring, egress monitoring, dependency review.