Media sanitization

Media sanitisation is the deliberate removal of data from storage media so that it cannot practically be recovered. NIST SP 800-88 Rev. 2 (2025), Guidelines for Media Sanitization, describes it as rendering access to target data infeasible for a given level of effort, and groups the methods into three categories. Clearing uses logical techniques, such as overwriting user-addressable storage, against simple non-invasive recovery. Purging uses physical or logical techniques, such as the device’s own sanitize commands, cryptographic erase or, for suitable magnetic media, degaussing, against state-of-the-art laboratory recovery. Physical destruction also defeats laboratory recovery and leaves the media unusable.

The method is chosen from the sensitivity of the information, whether the media will be reused, and whether it will leave the organisation’s control. Media type matters as much: degaussing does nothing to flash storage, and wear levelling can defeat host-based overwriting on solid-state drives. Sanitisation deals with data remanence, which logical deletion and formatting leave behind. The guideline frames sanitisation as an organisational programme: it calls for checking that each operation actually worked (sanitisation assurance) and for documenting it, for example with a certificate of sanitisation or a certificate of destruction.

Exam relevance: a scenario is likely to give a media type, a sensitivity and a destination, then ask for the appropriate method. Candidates are expected to weigh all three, rather than defaulting to the strongest option or to one that fails on that media.