In this article I want to talk about Applocker rule priority and rule sorting. As you know, Applocker has one security level or default action — Disallowed all except explicity allowed. This is common misunderstanding point for some administrators.

When you create Path or Publisher rule, it cannot uniquely identify particular file. For example, when you create Path rule such C:\BusinessPrograms\*, it will allow to run anything within C:\BusinessPrograms folder and all subfolders. Or, for example, you create Publisher rule that will allow to run any file that is signed with ‘Microsoft Corporation’ digital certificate, regardless of actual file location. It is common scenario when you want continue to block some files that are located in this folder or subfolders (in Path rule case) or files that are signed with particular certificate subject (in our case this is ‘Microsoft Corporation’ certificate), however.