Professional Windows® PowerShell

Chapter 16. Security

If you have worked through earlier chapters of this book, you will have begun to understand the huge potential that Windows PowerShell has for inspecting and manipulating Windows computers. Any software that allows you to discover what is happening on a system and modify that system and what is stored in its files has enormous power. That gives you power to do good. But with power also comes risk.

The designers of Windows PowerShell have spent significant time to analyze those risks. As a result, Windows PowerShell has an execution policy that, by default, prevents you running any PowerShell scripts. This is part of an approach that Microsoft calls Secure by Default. When you install the product, it is intended to be secure. This means that you need to take active steps to enable features that you want. In PowerShell executing scripts is a prominent example.

What is the reason for the Secure by Default approach? Imagine the scenario where you have just installed PowerShell and downloaded a script from the Internet or are sent a script by an acquaintance. With your possibly limited understanding of PowerShell, the risk of your running a malicious script has to be there. That script could remove files from your hard drive or run other scripts, and those scripts, in turn, could be malicious. The potential for damage is obvious. The security policies for Windows PowerShell are designed to allow you to configure security intelligently once you understand the implications ...