SketchUp has Extension policies you can select which will affect what extensions can and cannot be loaded when SketchUp starts. Registered Extension Developers can claim their software by signing it digitally, saying "I made this", but in a secure coded format. Everyone should download the most recent version of any extension they use from the Extension Warehouse, the author, or the original trusted download source. You might contact the author of any extensions that are not digitally signed and ask them to look into this new feature.
There are three extension policy modes: "Identified Extensions Only", "Approve Unidentified Extensions", and "Unrestricted". To access these settings, select Window > Extension Manager > Gear icon () > More Info icon ().
Policy Modes
Identified Extensions OnlyWhile in this mode, only extensions that have been digitally signed by a registered SketchUp Developer will be loaded by SketchUp.
Approve Unidentified ExtensionsThis mode lets you choose which extensions load each time SketchUp starts – you see a list of found extensions and ruby files in the Load Unidentified Extensions? dialog box. Select which of these you want to allow to load. SketchUp will remember which extensions you have approved. You will see the approval dialog box each time you start SketchUp so you can change your approvals before any extensions are loaded.
This is the least secure mode to select. All extensions and ruby files will load when SketchUp starts and the Load Unidentified Extensions? dialog box won’t open. This mode should only be used if you trust all the extensions that you have installed.
"Unrestricted" is the default Extension Loading Policy.
Switching Between Policy Modes
You can switch between modes at any time when SketchUp is running, but a restart is required to unload extensions that SketchUp already loaded.