Short answer
The security of a Microsoft 365 Copilot rollout depends on your tenant configuration, permissions and the way staff use it. Existing oversharing needs particular attention because Copilot can make accessible information easier to find.
What Copilot does with your data
This guide is about Microsoft 365 Copilot: the licensed version your organisation buys, used by staff signed in with their work (Microsoft Entra ID) account.
For Microsoft 365 Copilot, Microsoft states that it operates under Enterprise Data Protection: your prompts and Copilot’s responses are not used to train the underlying AI models, and your business data is not shared with other customers or made public. Copilot also respects your existing Microsoft 365 permissions and sensitivity labels: it can only use content the signed-in user is already allowed to open.
Make sure staff are using the right Copilot
There is more than one thing called Copilot, and they do not all handle data the same way. Microsoft’s consumer Copilot privacy FAQ is clear that the free, consumer version behaves differently: by default it can use conversations to help train Microsoft’s AI models (users can opt out), and it stores conversation history. The protections above apply to Microsoft 365 Copilot used with a work account, not to the consumer app signed in with a personal account.
In practice, safe adoption includes making sure staff use the licensed Microsoft 365 Copilot signed in with their work account, and understand they should not paste confidential material into a personal or consumer AI tool. This is where it connects to wider AI governance .
Review existing oversharing before enabling Copilot
Review the information users can already access before enabling Copilot.
Older Microsoft 365 environments may contain files shared with “everyone”, SharePoint sites with broad access and Teams or mailboxes whose membership has not been reviewed. Copilot can make this information easier to locate and summarise, including material that was shared more widely than intended.
A rollout should therefore include a review of access permissions and information governance.
What to check before you turn it on
A sensible Copilot readiness review usually looks at:
- where files, sites and Teams are shared more broadly than intended
- “anyone with the link” and sharing across the organisation that is no longer needed
- whether sensitivity labels are used for confidential material
- administrator accounts and accounts with excessive permissions
- guest and former staff access that was never removed
These checks also support the wider security of your Microsoft 365 environment.
A sensible way to roll it out
Start with a small pilot group rather than switching it on for everyone. Before that, review and tighten broad sharing and label sensitive material. Watch how Copilot is used during the pilot, and widen access once you are confident that what people can reach is actually what they should reach. Pair it with brief guidance for staff on what they should and should not put into any AI tool.
Where this fits with your wider security
Access controls, data ownership and Microsoft 365 configuration all need attention before a Copilot rollout. Reviewing them also improves the wider security of your tenant. If you are already preparing for Cyber Essentials or have had a Microsoft 365 security review , much of the groundwork will overlap. Our review guide explains the areas a Microsoft 365 security assessment should examine .
How Be Secure Cyber can help
We can review your Microsoft 365 access and configuration before a Copilot rollout, either as a one-off Microsoft 365 security review or as part of ongoing vCISO support . We identify access and sharing settings that need attention before staff begin using Copilot.
Speak to us about a Copilot readiness review.