Authentication abuse is the misuse of valid credentials, login methods, or authenticated sessions to make unauthorized activity appear legitimate. Rather than exploiting a flaw to bypass sign-in, an attacker may use stolen passwords, hijacked session tokens, or access obtained through another person’s account.
Because the activity can pass ordinary authentication checks, it may evade defenses focused only on blocking malware or invalid logins. In real attacks, abused access can be used to enter business platforms, access data, or carry out actions within routine workflows. Defenders can reduce risk with multifactor authentication, careful session management, and monitoring for unusual login context, access patterns, or transactions. A technically valid login should still be assessed against what is normal for the user and the business process.