TShock Security Escalation Exploit

Summary

### Impact An issue with the way OTAPI manages client connections results in stale UUIDs remaining on `RemoteClient` instances after a player disconnects. Because of this, if the following conditions are met a player may assume the login state of a previously connected player: 1. The server has UUID login enabled 2. An authenticated player disconnects 3. A subsequent player connects with a modified client that does not send the `ClientUUID#68` packet during connection 4. The server assigns the same `RemoteClient` object that belonged to the originally authenticated player to the newly connected player ### Patches TShock 5.2.1 hotfixes this issue. A more robust fix will be made to OTAPI itself. ### Workarounds Implement a RemoteClient reset event handler in a plugin like so: ```csharp public override void Initialize() { On.Terraria.RemoteClient.Reset += RemoteClient_Reset; } private static void RemoteClient_Reset(On.Terraria.RemoteClient.orig_Reset orig, RemoteClient client) { client.ClientUUID = null; orig(client); } ```