ISO 27001 Data Leakage Prevention
ISO 27001 Annex A 8.12 is about data leakage which means making sure that devices are protected to stop information being taken or read by people it should not be.
Table of contents
- ISO 27001 Data Leakage Prevention
- What is ISO 27001 Annex A 8.12?
- Why is data leakage prevention important?
- ISO 27001 Annex A 8.12 Explainer Video
- ISO 27001 Annex A 8.12 Podcast
- ISO 27001 Annex A 8.12 Free Training Video
- How to implement ISO 27001 Annex A 8.12
- How to comply
- How to pass an ISO 27001 Annex A 8.12 audit
- What will an auditor check?
- Top 3 ISO 27001 Annex A 8.12 mistakes and how to avoid them
- Related ISO 27001 Controls
- Further Reading
What is ISO 27001 Annex A 8.12?
ISO 27001 Annex A 8.12 Data Leakage Prevention is an ISO 27001 control that requires an organisation to stop data from being extracted or leaked from systems. This is usually done as a result of known weakness or having services and functionality enabled that is not needed and is easy to manipulate.
ISO 27001 Annex A 8.12 Purpose
ISO 27001 Annex A 8.12 is preventive control and a detective control that is to detect and prevent the unauthorised disclosure and extraction of information by individuals or systems.
ISO 27001 Annex A 8.12 Definition
The ISO 27001 standard defines ISO 27001 Annex A 8.12 as:
Data leakage prevention measures should be applied to systems, networks and any other devices that process, store or transmit sensitive information.
– ISO 27001:2022 Annex A 8.12 Data Leakage Prevention.
Why is data leakage prevention important?
Data leakage is a common way for people to gain access to information that they should not. Rather than rely on hacking or technical exploits it usually relies on the mis use of genuine product features. By applying policy, procedure and control based on an understanding of risk and business requirement can reduce the likelihood of information falling into the wrong hands.
ISO 27001 Annex A 8.12 Explainer Video
In this beginner’s guide to ISO 27001 Annex A 8.12 Data Leakage Prevention, ISO 27001 Lead Auditor Stuart Barker and his team talk you through what it is, how to implement in and how to pass the audit. Free ISO 27001 training.
ISO 27001 Annex A 8.12 Podcast
In this episode: Lead Auditor Stuart Barker and team do a deep dive into the ISO 27001:2022 Annex A 8.12 Data Leakage Prevention. The podcast explores what it is, why it is important and the path to compliance.
ISO 27001 Annex A 8.12 Free Training Video
In the video ISO 27001 Data Leakage Prevention Explained – ISO27001:2022 Annex A 8.12 I show you how to implement it and how to pass the audit.
How to implement ISO 27001 Annex A 8.12
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You are going to have to ensure that you:
- Identify the information that you want to protect
- Classify the information that you want to protect
- Implement controls to protect the information based on risk, classification and business need
- keep records
- Test the controls that you have to make sure they are working
There are several approaches to data leakage prevention and the most common is to implement a data leakage prevention tool.
Data Leakage Prevention Tool
A Data Leakage Prevention Tool (DLP) is a specific tool that has been designed to track, detect and protect information based on rules using technology.
These tools can often be applied to structured and unstructured data. They can detect and / or prevent the disclosure of sensitive data for example sending information to, or from, personal and cloud emails, and sending information to cloud storage devices.
The more traditional examples of data leakage prevention are the locking down, or preventing the use of, attached media such as external hard drives and USB devices. Also the restricting of printing.
Implementing a DLP tool will take some planning. It can be easy to implement a tool that prevents people from being able to carry out their role. Spending time to understand what people need to do and then implementing proportionate controls is the key.
A good approach to implementing a DLP tool would be to first implement it in monitoring mode and to analyse the results before turning on more restrictive controls. The ability to request access or appeal a blocked control will help maintain the smooth operation of the business.
It is also important to consult with your legal team and ensure that what ever you do it is within the bounds of all laws and regulations. To do their job correctly, DLP tools will have access to all data and often the personal data of employees and customers.
Some things cannot be covered directly in a DLP tool. Taking screen shots, the use of cameras, video streaming of screens should be addressed in terms and conditions of employment, policies, training, education and physical controls such as not allowing cameras or phones into the work environment.
Backups can be a source of data leakage so having a strong backup policy that requires backups to be encrypted should be considered.
How to comply
To comply with ISO 27001 Annex A 8.12 you are going to implement the ‘how’ to the ‘what’ the control is expecting.
In short measure you are going to:
- Understand and record the legal, regulatory and contractual requirements you have for data
- Conduct a risk assessment
- Based on the legal, regulatory, contractual requirements and the risk assessment you will implement an
information classification scheme - Implement and communicate your topic specific policy on access control
- Document and implement your processes and technical implementations for data leakage prevention
- Check that the controls are working by conducting internal audits
How to pass an ISO 27001 Annex A 8.12 audit
To pass an audit of ISO 27001 Annex A 8.12 Data leakage prevention you are going to make sure that you have followed the steps above in how to comply.
You are going to do that by first conducting an internal audit, following the How to Conduct an ISO 27001 Internal Audit Guide.
What will an auditor check?
The audit is going to check a number of areas. Lets go through the main ones
1. That you have documentation
What this means is that you need to show that you have documented your legal, regulatory and contractual requirements
for data leakage prevention. Where data protection laws exist that you have documented what those laws are and what those
requirements are. That you have an information classification scheme and a topic specific policy for access control and
that you have documented your data leakage prevention techniques.
2. That you have have implemented data leakage prevention appropriately
They will look at systems to seek evidence of data leakage prevention. They will review endpoints to see that it is installed. System generated reports and logs will be reviewed. Process documents will be read and processes observed to ensure the documents are being followed. Examples of where the DLP has caught and handled something will be sought.
3. That you have conducted internal audits
The audit will want to see that you have tested the controls and evidenced that they are operating. This is usually in the form of the required internal audits. They will check the records and outputs of those internal audits.
Top 3 ISO 27001 Annex A 8.12 mistakes and how to avoid them
In my experience, the top 3 mistakes people make for ISO 27001 Annex A 8.12 Data leakage prevention are
1. You block everything
This is a common mistake we see. That the teams in charge of the data leakage prevention tool become a bit over zealous and lock everything down causing annoyance, irritation and preventing the business from operating. Be sure to implement proportionately.
2. You don’t know your legal obligations
This is a massive mistake that we see, where people assume ISO 27001 is just information security and forget that it also checks that appropriate laws are being followed, and in particular data protection laws. Cost saving by not having a data protection expert or ignoring data protection law entirely is a common mistake we see people make when cutting corners and saving costs.
3. Your document and version control is wrong
Keeping your document version control up to date, making sure that version numbers match where used, having a review evidenced in the last 12 months, having documents that have no comments in are all good practices.
Related ISO 27001 Controls
ISO 27001 Clause 7.3 Awareness
ISO 27001 Annex A 8.15 Logging
ISO 27001 Annex A 8.16 Monitoring Activities
Further Reading
ISO 27001 Information Security Policy Beginner’s Guide
ISO 27001 Data Protection Policy Template
About the author
Stuart Barker is a veteran practitioner with over 30 years of experience in systems security and risk management.
Holding an MSc in Software and Systems Security, Stuart combines academic rigor with extensive operational experience. His background includes over a decade leading Data Governance for General Electric (GE) across Europe, as well as founding and exiting a successful cyber security consultancy.
As a qualified ISO 27001 Lead Auditor and Lead Implementer, Stuart possesses distinct insight into the specific evidence standards required by certification bodies. He has successfully guided hundreds of organizations – from high-growth technology startups to enterprise financial institutions – through the audit lifecycle.
His toolkits represents the distillation of that field experience into a standardised framework. They move beyond theoretical compliance, providing a pragmatic, auditor-verified methodology designed to satisfy ISO/IEC 27001:2022 while minimising operational friction.