Trying to stop someone opening a file you don’t want them to is relatively easy and putting some form of encryption on it can easily be done. It is a slightly different story if you actually want to stop somebody executing a specific program on a computer. There are ways to do similar things through restricted user accounts where each user can be setup individually. But some people I know use only one Admin account for the whole family which isn’t good for privacy or security.
What if you want to let someone else use your computer temporarily but don’t want them to perhaps run a specific program like an email program or browser while they’re on it? Or maybe a short term block is to be put in place on a youngster’s laptop browser or messaging application. Applying a short term restriction is a bit more tricky than a permanent one.
An interesting little utility called AppAdmin does this for you but not by using file encryption or third party methods to block the program. It does this through adding a Group Policy entry into the registry, which will then not allow the file to be executed. Knowledgeable people will point out the Group Policy Editor is not available on all versions of Windows, but AppAdmin also works on those systems where it is not present like XP Home and Windows 7 Home Premium.
The program is portable and comes in a zip archive. The included ini file can easily be edited to allow for adding non supported languages.
The interface is pretty simple and to block a program or file, drag it onto the window or select it through a requester by pressing the ‘Block’ button. As soon as it appears in the window, it is blocked and cannot be executed. Do note that selecting a shortcut to a program won’t work, the executable itself has to be added. Luckily, this is a program you are not going to add hundreds of files to as multiple selections or adding a folder and its contents in one go is not supported.
Internet Explorer blocked in XP Home
The same in Windows 7 Home Premium
AppAdmin uses the MD5 hash information of the file while applying the block so even renaming it will not mean it can be executed. Some files may need a restart of Explorer.exe to recognise they have been blocked and AppAdmin has a button to do this. To unblock anything and make it accessable again, put a tick into the box and click ‘Unblock selected’.
The ‘Password’ button does not password protect the files but the AppAdmin program itself which will ask for it when you launch the program to do any blocking or unblocking. To clear an already set password just type it in the ‘Old Pasword’ box.
While this does work for preventing executable files from being run, using it for data files is not really effective in the sense that although they are unable to run on this system, they will work fine on any other machine because the restriction policy is only for the PC you run AppAdmin on. I also found simply choosing to edit a data file through a context menu program like Notepad++ still allows you to edit the file, thus changing its MD5 hash and allowing it to be executed. This program is only really at its most effective on installed software or something that can’t easily be transferred to another system.
To quickly or temporarily block access to a few applications like browsers, system utilities, instant messengers or files from being executed, AppAdmin has its uses and is quite handy. But is not a substitute for protecting or encrypting data like documents especially those that can be easily transported to other systems.
Compatible with Windows 2000, XP, Vista and 7. Tested fine on XP Home and Win 7 64bit.