ASD ISM 0836 Overwriting EEPROM for complete data sanitisation
What it says
Non-volatile EEPROM media is sanitised by overwriting it at least once in its entirety with a random pattern followed by a read back for verification.
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What it means
In plain EnglishErase EEPROM data by overwriting it with random data and checking it to ensure it's properly wiped.
This control is about making sure any data stored in EEPROM (a type of computer memory) is completely erased when it's no longer needed. EEPROM holds onto information even when powered off, so if it's not properly wiped, sensitive data could fall into the wrong hands. By overwriting it with random patterns, we ensure that whatever was there before can't be recovered, protecting against data leaks and privacy breaches.
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Why it matters
Failing to properly sanitise EEPROM increases the risk of sensitive data being retrieved after disposal, potentially leading to data breaches.
How to implement
The IT team should be responsible for creating a procedure to overwrite EEPROM memory.
They can do this by using software designed for this purpose, which writes random patterns of data over the existing information on the EEPROM. This needs to be done routinely to prevent data recovery.
Managers should make sure their teams understand the importance of data sanitisation.
They can achieve this by organising training sessions that explain why encryption and data wiping are crucial for protecting sensitive information stored on EEPROM.
Procurement officers must ensure that all equipment purchased has the capability to overwrite EEPROM as per the required security standards.
This means checking product specifications and, if necessary, consulting with vendors about the device's ability to securely erase data.
Systems administrators should regularly audit the data sanitisation processes for EEPROM.
They can do this by scheduling periodic checks to verify that the overwrite functions are correctly implemented and documented.
Security officers should draft a policy that mandates the sanitisation of any EEPROM-containing devices before disposal or reuse.
This policy should outline the steps for ensuring data has been overwritten and specify who is responsible for verifying the process.
Keep it running
Overwrite the entire EEPROM at least once with a random pattern, then read back the full device to verify the overwrite succeeded.
Evidence and audit
- Check 1 of 5What an auditor asks for
Ask for
The written data sanitisation procedures for EEPROM: Request the document that details the steps taken to overwrite data on EEPROM.
Look at
Whether the procedure includes using random patterns for overwriting and a verification step.
Good evidence
Procedure will have these elements clearly documented and assigned to specific staff roles.
- Check 2 of 5What an auditor asks for
Ask for
To see a log of past EEPROM sanitisations.
Look at
Entries that show when each sanitisation occurred and who performed it.
Good evidence
Log will show regular intervals consistent with the policy and have entries signed off by an IT professional.
- Check 3 of 5What an auditor asks for
Ask for
A demonstration of the EEPROM overwrite process: Request the team to walkthrough the overwrite procedure on a test EEPROM.
Look at
Their use of approved software to perform the task.
Good evidence
Demonstration will result in a properly wiped test memory that is verified immediately.
- Check 4 of 5What an auditor asks for
Ask for
Training records related to EEPROM sanitisation: Request records showing that team members have been trained on this process.
Look at
Details such as dates of training and names of attendees. Good training records should show that all relevant staff are informed about the necessity and execution of this process.
- Check 5 of 5What an auditor asks for
Ask for
Documentation of any issues found during EEPROM sanitisation: Request records of any anomalies or problems encountered.
Look at
Follow-up actions taken to address these issues. A well-handled issue will have clear documentation and subsequent changes to the process if required.
Mappings
Closest match in ISO/IEC 27001: A.7.10, Secure management of storage media, which this control partially meets.
ISO/IEC 27001: 2 mappings
This control partially meets A.7.10.
ISM-0836 requires sanitising EEPROM by fully overwriting it with a random pattern and verifying the overwrite via read back. This relates to ISO/IEC 27001:2022 Annex A 7.10 because sanitisation and secure handling at end-of-life are part of managing storage media through its lifecycle in accordance with classification and handling requirements. Annex A 7.10 is broader lifecycle governance including acquisition, use, transport, and disposal, whereas ISM-0836 is a specific technical sanitisation technique for one non-volatile media type.
This control partially meets A.7.14.
Annex A 7.14 requires ensuring sensitive data is removed or securely overwritten from storage media before equipment disposal or re-use. ISM-0836 provides a specific sanitisation method for non-volatile EEPROM (overwrite with random pattern and verify by read-back) that implements Annex A 7.14 for that media type. ISM-0836 does not cover other media types, procedural verification for all equipment, or licensed software removal explicitly mentioned in Annex A 7.14.
Mappings show how controls relate across frameworks. They do not imply full equivalence or certification.