What are memory cards and USB storage?
Small portable storage devices primarily using NAND flash include:
- SD / microSD cards(cameras, tablets and mobile devices)
- CF / CFast / CFexpress cards(professional photography and surveillance)
- USB flash drives(Type-A, Type-C and enterprise encrypted USB)
- External SSDs / HDDs(mobile enterprise work)
- Embedded eMMC(enterprise tablets, POS and IoT devices)
Characteristics:Very small, easily lost and often forgotten;、capacity is frequently underestimated(modern microSD cards can reach 1 TB).
Why is controlled destruction needed?
Enterprise USB drives and memory cards can create overlooked exposure:
- Departing employees' personal USB drives may contain company data.
- Surveillance cards may retain 6–12 months of images.
- Development/test SD cards may hold product prototypes.
- Similar-looking cards can be confused with personal devices.
- An encrypted USB remains exposed if usable keys are not addressed.
NIST SP 800-88 outcome levels
| Level | Method | Effect on memory cards |
|---|---|---|
| Clear | Single overwrite via a reader | Limited, as with SSDs: reserved or bad blocks may be inaccessible |
| Purge | Cryptographic Erase on supported enterprise encrypted USB | Effective subject to prerequisites |
| Destroy | Physical shredding | A conservative, verifiable principal method |
Key point: Most consumer cards do not support a dependable Secure Erase command. Suitable Physical Destruction is therefore a primary option.
DIN 66399 reference levels (E class)
Standards-version note: DIN lists DIN 66399:2012 as withdrawn and recommends ISO/IEC 21964. The levels and particle sizes below are retained from customer-supplied material for requirement discussions. Formal projects must confirm the adopted edition, equipment capability, contract and applicable law; this does not mean KYI is certified or a project is automatically compliant.
As with SSDs, the source reference proposes E-5 or above (≤ 10 mm²), subject to the adopted project criteria.
Treatment-method comparison
Method A | Physical Shredding
Use suitable equipment to treat cases, circuit boards and NAND chips to the approved particle criterion.
Benefit: A conservative, verifiable option with visible evidence.
Limitations: Prevents reuse and requires the applicable E-class particle outcome.
KYI project context: A primary option for most card and USB destruction projects.
Method B | Cryptographic Erase on supported encrypted devices
Enterprise hardware-encrypted USB devices, such as supported IronKey models, may allow key removal through their management interface.
Benefit: Fast and may preserve device reuse.
Limitations: Limited to suitable supported brands and models.
KYI project context: Standardized encrypted-USB estates with an established key-management system.
Method C | Overwrite as a supporting control
Reader-based overwrite is limited by wear leveling and reserved areas; it cannot by itself establish treatment of every physical location.
KYI project context: Treat as a supporting step rather than the assumed principal destruction method.
Common pitfalls and misconceptions
- Misconception 1: Formatting is enough As with SSDs, formatting does not establish treatment of every physical block.
- Misconception 2: Water destroys the data NAND content may remain recoverable after water exposure.
- Pitfall 3: USB drives in employee drawers Individually assigned USB drives are often omitted from retirement inventories.
- Pitfall 4: Surveillance SD cards Continuously operating surveillance systems can hold substantial video; include rotation and treatment in policy.
- Pitfall 5: Memory inside POS, printers and projectors Embedded devices may retain enterprise configuration and usage history.
- Pitfall 6: USB drives not returned at departure Include issued media in the employee-exit checklist.
KYI decision path
Start with three questions:
- Is it an enterprise encrypted device? → Assess qualified key erasure and the approved sample/physical-treatment plan; otherwise assess direct Physical Destruction.
- What is the quantity? → Large batches (100+ items): batch shredding. Small quantities may join another media project.
- Are there hidden storage locations? → Check surveillance, POS, printers and embedded equipment.
Verification and records
A project memory-card/USB destruction record may include:
- Count and format (SD/CF/USB/external)
- Originating department or device
- Treatment method and particle reference
- Imagery, if requested
Applicable industries
Enterprises generally, surveillance/security, photography, medical imaging and finance