ASD ISM 0133 Responding to data spills by restricting access
What it says
When a data spill occurs, data owners are advised and access to the data is restricted.
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What it means
In plain EnglishWhen a data spill occurs, notify the data owner and limit access to protect information.
Imagine one of your staff accidentally sends confidential customer details to the wrong email list. This is a data spill. It's crucial to act fast by telling the person in charge of that information and restricting who can see it. If you don't, more people might see the confidential data, which can lead to privacy breaches and loss of trust.
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Why it matters
If access isn't promptly restricted and data owners advised after a data spill, unauthorised disclosure may occur, increasing impact and undermining trust.
How to implement
Data Owners should be promptly notified: As soon as a data spill is detected, the person who manages the affected information should be informed immediately.
This can be done through a quick phone call or an email marked as urgent.
IT Team should restrict access: The IT staff need to limit who can access the spilled data to prevent further exposure.
They can do this by removing access privileges to the affected files or folders in the system as soon as possible.
Managers need to inform affected parties: The manager must notify any parties whose data might have been compromised.
This should be done transparently and swiftly, explaining what data was affected and what steps are being taken to address the situation.
HR should provide guidance: The HR department should offer support and guidance to the employee involved in the spill, ensuring they understand what went wrong and how to avoid similar incidents in the future.
Procurement should review third-party agreements: If the data spill involves information shared with outside partners, the procurement team should check existing agreements to ensure there's a clear protocol for handling such incidents, including any notification requirements.
Keep it running
On a data spill, immediately advise data owners and restrict access to affected data; review access logs and confirm restrictions remain until containment is complete.
Evidence and audit
- Check 1 of 5What an auditor asks for
Ask for
Incident response logs: Request a report detailing when the data spill was identified, who was notified, and what immediate actions were taken.
Look at
Timestamps and clear records of notifications.
Good evidence
Is a detailed log showing swift notification to all relevant parties.
- Check 2 of 5What an auditor asks for
Look at
Who had access before and whether it was limited after the incident.
Good evidence
Shows prompt and appropriate restriction of access to affected data.
- Check 3 of 5What an auditor asks for
Ask for
How the team handles data spills and verifies restricted access.
Look at
Clear, confident responses about their process.
Good evidence
Shows they understand protocol steps and can cite past incident handling.
- Check 4 of 5What an auditor asks for
Look at
Clarity and timeliness.
Good evidence
Includes prompt, transparent communication detailing the incident and impact.
- Check 5 of 5What an auditor asks for
Look at
Comprehensive terms covering notification requirements in case of breaches.
Good evidence
Contains clear procedural guidelines and vendor obligations.
Mappings
Closest match in ISO/IEC 27001: A.8.3, Restrict access to information and assets, which partially overlaps with this control.
ISO/IEC 27001: 1 mapping
This control partially overlaps A.8.3.
Annex A 8.3 requires organisations to restrict access to information and associated assets in accordance with an access control policy. ISM-0133 relates by requiring access to spilled data to be restricted as an incident response containment measure. The overlap is in restricting access, but ISM-0133 is event-driven (data spill response) whereas Annex A 8.3 is a standing policy-based control for normal operations.
ASD Essential Eight: 1 mapping
This control partially overlaps E8-RA-ML3.1.
ISM-0133 requires notifying the data owner and restricting access to data when a data spill occurs to contain further unauthorised exposure. ASD Essential Eight E8-RA-ML3.1 requires privileged access to systems, applications and data repositories to be limited to what is necessary for duties, which reduces who can access spilled data and can be tightened further during containment. E8-RA-ML3.1 is a standing least-privilege requirement, while ISM-0133 is an incident response action that applies to all relevant access (not just privileged) and includes data owner notification.
Mappings show how controls relate across frameworks. They do not imply full equivalence or certification.




