An authentication file is a local file that stores information an application or service uses to verify a user or authorize access. It may contain tokens, credentials, or configuration data, and can let software connect without asking the user to sign in each time.
These files matter because malware that can read a developer’s device may copy them and attempt to access linked accounts or services. In real-world attacks, information stealers search for authentication files alongside browser data, cloud credentials, and other secrets. Defenders should limit file permissions, avoid storing long-lived credentials where possible, and treat a suspected infection as a credential exposure: investigate activity and revoke or rotate potentially affected access.