SECURING FIBRE CHANNEL FABRICS - Brocade

Information Disposal and SanitizationThere are several accepted methods to sanitize and destroy data. TheNIST Special Publication 800-88 provides some useful guidelines onsanitizing media. This publication proposes four basic types of datasanitization methods, described in the following sections.DisposalDiscarding media with no sanitization concerns is appropriate only fornon-confidential or non-sensitive information. Simply deleting files andemptying the recycle bin or reformatting a disk drive could meet thisrequirement.ClearingAcceptable for non-sensitive data, clearing protects confidentiality byclearing information using an accepted overwriting method to protectagainst attacks using data scavenging tools. Simple file deletion is notacceptable at this level of sanitization. However, overwriting does notwork on failed or defective media, making it inappropriate for certainenvironments. Data clearing is also referred to as data shredding, erasure,or wiping.The clearing method uses one of several techniques to overwrite dataon a functional disk drive. Clearing can be accomplished in a variety ofways and several standard algorithms have been developed to accomplishthis. Although this method is sufficient for moderately sensitivedata, it is usually not appropriate for highly sensitive data. The read/write mechanisms of disk drives are not precise enough to exactlyoverlay new data over old data. It is entirely possible to see smallbands of residual data underlying the new data using sophisticatedforensic equipment such as magnetic force microscopes. Clearly, suchforensic equipment is not available to the average hacker, but it certainlycould be used by a foreign government, for example, if anenemy's sensitive disk drive should fall into their hands.There has been controversy around this subject as a result of conflictingresearch data on the ability to recover overwritten data. Using specialmicroscopes, some researchers were able to demonstrate that overwrittendata could be recovered. More recent work has demonstrated thatmodern drives are more accurate and it is no longer possible to performsuch an attack. Nevertheless, it is entirely possible that even moderndrives could encounter calibration issues resulting from routine wearand tear, which could allow residual data to be observed.Securing Fibre Channel Fabrics 69