AppLocker allows you to enforce a security policy which can block specific programs or allow only programs on a whitelist to be executed.
Windows 7 Ultimate offers new application control policies with AppLocker, a flexible, easy-to-use mechanism that enables IT professionals to specify exactly what is allowed to run on user desktops. AppLocker restricts unauthorized software while allowing applications, installation programs, and scripts that users need. With this capability, IT professionals can realize the security, operational, and compliance benefits of application standardization.
AppLocker provides simple, powerful, rule-based structures for specifying which applications can run that are centrally managed using Group Policy. It introduces "publisher rules" that are based on an application's digital signature, making it possible to build strong rules that account for application updates. For example, an organization can create a rule to "allow all versions greater than 1.0 of an application to run if signed by the vendor." With correctly structured rules, IT professionals can safely deploy updates to allowed applications without having to build a new rule for each version update.
AppLocker allows to configure the programs in 3 ways: