How do I protect my server from backdoored addons in the first place?

The Backdoor Scanner catches known malicious patterns, but a few habits go a long way in preventing infection before you ever need to run it.

Only install addons from the Steam Workshop or a source you genuinely trust. Never install a "leaked" or cracked version of a paid addon; these are the single most common source of backdoors, almost by definition, since someone had to redistribute them outside the original author's control. Do not allow untrusted SFTP or file uploads from anyone you have not vetted. Run the Backdoor Scanner after every batch of new addon installs, not just when something feels wrong.

Before installing an unfamiliar addon: check how long it has been on the Workshop and its update history, be cautious of an addon with a high subscriber count but no reviews or discussion, and if you are unsure, test it on a separate/throwaway server first rather than your live community server.

If you do suspect an active backdoor: stop the server immediately, change your panel password and RCON password, rotate your database passwords, delete the suspect addon, and review the Activity Log for unusual file access. Treat any admin accounts as potentially compromised too; a backdoor can add rogue superadmins, so revoke and re-grant admin access from scratch afterwards rather than assuming the existing list is trustworthy.