Legitimate access is entry to a system or data using valid credentials and permissions. It is normally necessary for employees, contractors, suppliers, and services to do their work, but a valid login does not guarantee that activity is authorized in context or safe.
In cyber security, legitimate access can be misused when credentials are stolen, permissions are excessive, or an authorized user shares or removes data outside policy. Attacks may therefore resemble routine account activity rather than a break-in. Defenses include least-privilege permissions, multi-factor authentication, regular access reviews, logging and monitoring of file sharing and downloads, and promptly revoking access that is no longer needed. These controls help teams identify misuse without assuming every authorized user is malicious.