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Cyber security incidents
ASD ISMISM-0133

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.

Quoted as published. Everything else on this page is written by Control Stack.

What it means

In plain English

When 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.

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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  1. 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.

  2. 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.

  3. 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.

  4. Check 4 of 5What an auditor asks for

    Look at

    Clarity and timeliness.

    Good evidence

    Includes prompt, transparent communication detailing the incident and impact.

  5. 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 27001

ISO/IEC 27001: 1 mapping

Essential Eight

ASD Essential Eight: 1 mapping

Mappings show how controls relate across frameworks. They do not imply full equivalence or certification.