Understanding Windows 7 AppLocker

Our guest blogger is Daniel Nerenberg. He is an MCT,MCSA,MCSE,MCTS,MVP, STEP Member and an independent consultant based in Montreal. He is also the President of the Montreal IT pro user group. Daniel has written and consulted on the topics of Windows deployment, application virtualization, and Windows infrastructure. Window 7 RTM has been available for just a few weeks now, but already IT Pros everywhere are diving into great new features. One of the more exciting features introduced in Windows 7 is AppLocker. Many of you know about Software Restriction Policies, they allow you to block the execution of a program by file name or hash calculation. You probably also know how it was a race to block applications in our network with these methods. Users could change the name of the file, or applications updates so frequently that you would constantly need to generate new hash files. AppLocker works under the premise that its easier to allow the applications you want, and block the rest. If youre running a Windows 7 machine you can see AppLocker by typing gpedit.msc into your search bar and pressing enter. You can define policies based on executables, Windows installers, and scripts. Creating a new policy is simple. Right-click on any of the 3 categories and click Create New Rule. You can create a policy to allow or deny an executable. You can also select which groups the rule will apply to. You can choose to create a rule based on a publisher (the program needs to be signed), a program path, or a file hash (usually a good choice if the program isnt signed). For this example I chose publisher. The Rule Wizard uses the information stored application signing certificate to learn about the application. You can adjust what level of information youll allow for an application. In the above example the policy will only allow Internet Explorer 8.0.0.0 and above to run on the computer. You can use the same steps to create exceptions for specific applications. One of the more convenient features is the ability to automatically generate rules. If you right click on any of the 3 categories and click Automatically Generate Rules you can quickly generate a list of rules based on applications that are already install on the computer (saving you a lot of work to get going with AppLocker!). In this example, we scan your applications in the Program Files directory and create rules for those programs to run. Perfect for creating a baseline set of rules for applications on a gold image or group policy quickly. So to summarize, AppLocker allows you from a high level (Publisher) to a granular level (Version) to choose what applications you would like to allow users to run (white listing) rather than creating long lists of what applications they cannot use (black listing).