The Windows Encrypted File System (EFS) safety measure is a double-edged sword when it comes to security. This feature in Windows XP Professional and Windows Servers lets users easily encrypt files and folders to protect them from snoopers.
The other side of the "edge" is that it's too easy. While EFS can be an important component of a well-designed storage security program, you don't need any kind of security program to use it. In fact, you don't even need administrative permission in the default configuration.
In the default configuration, any user can activate EFS and merrily start encrypting away without any provision for recovery or key management. If something goes wrong, all those files and folders can be just as lost as they would be if the disk had been corrupted by a virus.
Windows EFS provides a fairly sophisticated key management system that includes assigning a recovery authority for each user who creates EFS files. Microsoft recommends that anyone using EFS have at least two recovery authorities for each user of EFS and that the keys be managed in a safe and secure manner. However, because EFS is so easy to implement, users may jump the gun and start using EFS without the necessary protections in place. What's worse, organizations sometimes decide to use EFS without making proper allowances for managing and securing encrypted files.
Until your organization has an effective EFS policy in place, the best move is to deactivate EFS. This can be done with the local Group Policy (for individual computers) or the Domain Group Policy for domains.
Anyone thinking of using EFS in their organization should read Microsoft's tech note, "Best Practices for the Encrypting File System."
Rick Cook has been writing about mass storage since the days when the term meant an 80 K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last 20 years he has been a freelance writer specializing in storage and other computer issues.
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