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Consistent with the least privilege and separation of duties concepts discussed previously, your organization should restrict access to and usage of removable media to specifically authorized staff members who need it for their daily duties, based on their specific roles.

To do this, there must be an element of physical protection and storage that is commensurate with the sensitivity and classification of the data on the media. Here are a few examples, illustrating different levels of protection:

 Backup copies of audit logs are kept in a locked desk drawer or cabinet, where the key is available only to administrators who may need to review the logs.

 Signed hard-copy health insurance forms are in a locked file cabinet in a room restricted to HR staff via proximity-badge access.

 An external hard drive with classified data on it is fully encrypted and is in a locked safe in a protected area, accessible only to users with appropriate security clearance and need to know. The encrypted files can be decrypted only on systems that are cleared for using information at that level and then only when being used by a user with matching privileges.

As you can see in the examples, different layers of both physical and logical access control can and should be provided to media to meet your information security needs. There are additional measures to consider, based on the sensitivity and criticality of your media. You may need to create redundant copies of critical media to mitigate accidental damage or loss. Suitable encryption and other techniques can protect the classified data while it is at rest (stored on the media) and in motion between the media and the systems that are processing it (and making it available to users). Remember, too, that all storage media and technologies suffer degradation over time, resulting in data loss. Your data integrity, availability, and retention needs may drive you to establish a media rotation strategy, which periodically moves the files (the in-use set and the backup copies) to new, fresh media. (Data centers have been doing this since the 1960s, as they discovered that reels of magnetic tape quite literally saw bits flaking off when they hung in storage for too long.) Finally, you should treat the collection of all of your sensitive, critical information and the media it is stored on as a library of assets and define formal processes for periodically verifying your inventory of media, for formally authorizing users to check media in and out of the media library, and for leaving an audit trail. These processes should be followed until the media is either sanitized and then downgraded for uncontrolled use (not recommended—it's a false economy!) or destroyed for disposal, using approved equipment and methods in either case.