Windows 7 security primer, part three

AppLocker wards off Trojan attacks by preventing users from launching forbidden files and apps

Malicious Trojans continue to plague end-users' desktops, yet most machines aren't exploited due to missing patches (although this is the second biggest cause), unpatched zero days (almost never a factor), drive-by downloads, or misconfigurations. Nope, most systems are infected because users are duped into intentionally installing programs that Web sites say they need. These socially engineered Trojans come in the guise of anti-virus scanners, needed codecs for a media player, fake patches, and just about any other bait the bad guys can concoct to lure end-users into installing their Trojan file.

The most effective means of thwarting these types of threats in an enterprise environment is preventing end-users from installing unapproved programs. If you leave the decision up to end-users, they will almost always make the wrong choice. If they didn't, malware wouldn't be nearly as popular as it is today.

[ InfoWorld's Roger Grimes explains how to stop data leaks in an enlightening 30-minute webcast, Data Loss Prevention, which covers the tools and techniques used by experienced security pros. ]

Microsoft's most sophisticated solution to the problem is AppLocker, an application-control feature included in Windows 7 (Ultimate and Enterprise versions) and Windows Server 2008 R2. This week, in part three of my ongoing series about Windows 7 security improvements, I'll discuss AppLocker. (You can read my part one, an overview of some of the security changes, and part two, covering XP Mode. Also, for the sake of full disclosure, I'm a full-time employee at Microsoft.)

Opening up AppLocker
AppLocker is an improvement on the Software Restriction Policies (SRP) introduced with Windows XP Professional. AppLocker allows you to define application execution rules and exceptions based on file attributes such as path, publisher, product name, file name, file version, and so on. You can then assign policies to computers, users, security groups, and organizational units via Active Directory.

[ Check out the InfoWorld Test Center's roundup of other application-control programs. ]

You can configure AppLocker locally using the Local Computer Policy object (gpedit.msc) or via Active Directory and Group Policy Objects (GPOs). AppLocker relies on the built-in Application Identity service, which is normally set to manual startup type by default. Administrators should configure the service to start automatically.

Within the local or group policy object, AppLocker is enabled and configured under the \Computer Configuration\Windows Settings\Security Settings\Application Control Policies container.

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