AutoRun

Autorun refers to a capability in computer systems to automatically execute a program or script when a removable device or media is accessed, or when software is installed from a package. It is most closely associated with removable media such as CDs, DVDs, and USB drives, and is often implemented via a small configuration file that instructs the system what to run.

In Windows, autorun became widely known through the Autorun and Autoplay features. A drive can contain a file named autorun.inf at its root. The [Autorun] section may specify an action description, a drive icon, or the executable to run via the shell\open\command entry. A typical setup would indicate an open command to launch a setup program or an application automatically when the media is inserted. While this facilitated convenient installation from media, it also created security risks.

Modern Windows versions have restricted autorun behavior, especially for USB drives. Autorun from removable drives is largely disabled by default to reduce malware propagation; autoplay prompts the user with options instead of silently executing. For CD/DVD media, certain actions may still be permitted with user confirmation, and the exact behavior can vary by version and policy.

Outside Windows, autorun is less commonly supported as a universal feature. Linux and macOS typically require manual mounting and user initiation to execute programs from external media. Security-focused environments discourage silent execution of unknown software from external sources.

Security considerations and best practices emphasize disabling or limiting automatic execution from removable media, keeping systems updated, and educating users to avoid running untrusted programs. Autorun remains a historical and security-conscious fixture in the evolution of operating system design and media handling.