Microsoft 365 Copilot does not create new permissions. It can only use content that the person submitting the prompt is already authorised to access. The risk is that many Microsoft 365 environments contain old SharePoint sites, broad sharing links and inherited permissions that give employees technical access to information they no longer need.
Copilot can surface that content far faster than a traditional search. A salary spreadsheet or confidential planning document may therefore appear in a response even though nobody intentionally shared it with that employee. Microsoft’s 2026 Data Security Index found that 32% of surveyed organisations’ data security incidents involved generative AI tools, showing that both approved and unapproved AI use now require active governance.
What Microsoft Purview Can Control
Microsoft Purview provides data security, information protection, audit and compliance controls across Microsoft 365 and supported AI applications.
| Purview capability | How it helps |
|---|---|
| Data Loss Prevention for Copilot | Can prevent Copilot from processing files and emails carrying selected sensitivity labels |
| Data Security Posture Management | Highlights AI activity, sensitive-data risks and potentially overshared SharePoint content |
| Sensitivity labels and encryption | Classifies information and can restrict who may view or extract protected content |
| Audit | Records supported Copilot prompts, responses and references to files, emails, sites or other resources |
| Insider Risk Management | Helps authorised teams investigate unusual or risky data access and sharing patterns |
DLP for Microsoft 365 Copilot and Copilot Chat can exclude labelled files and emails from response generation. However, applying a “Confidential” label alone does not automatically block Copilot. The organisation must define the label correctly and configure the relevant DLP or encryption controls.
Clean Up Access Before Expanding Copilot
The most important work happens before a large Copilot rollout. Start by identifying sites shared with “Everyone except external users”, organisation-wide groups, anonymous links or former employees. SharePoint data access governance reports and site access reviews can help locate potentially overshared content.
Then:
- Remove unnecessary memberships and sharing links.
- Assign accountable owners to every active site.
- Restrict access to business-critical locations.
- Apply a consistent sensitivity-label structure.
- Test DLP policies before enforcing them broadly.
- Review audit records and high-risk AI activity regularly.
Reading what a Microsoft 365 assessment involves can help define the scope. A Microsoft 365 support company should review licensing as well as configuration because advanced Purview controls may require Microsoft 365 E5, the Microsoft Purview Suite, other add-ons or pay-as-you-go services.
A dark web security monitoring company can identify exposed credentials, while a cloud backup solutions company can strengthen recovery. Neither service replaces access governance inside Microsoft 365.
Do Not Ignore Shadow AI
Copilot is only one part of the problem. Employees may paste work content into consumer versions of ChatGPT, Gemini, DeepSeek or other tools. Purview can monitor or restrict some third-party AI interactions through Endpoint DLP, managed devices, Edge for Business, browser controls and network data security. Coverage depends on the application, device, browser, licensing and policy configuration.
Clear rules and staff education are still necessary. Anti-phishing services should be supported by practical training on prompts, confidential information and approved AI tools. A business platform migration services provider should also include permissions, labels, retention and AI governance in any Microsoft 365 migration.
Businesses already using Microsoft Copilot should review governance alongside the key features of Microsoft 365 Copilot for business, not after deployment. Organisations relying on IT services across Europe should apply consistent controls while assessing the legal requirements relevant to each operation.
Frequently Asked Questions
Can Purview prevent every accidental disclosure?
No. Purview reduces risk, but permissions, labels, policies, devices and staff behaviour must all be managed correctly.
Does Purview automatically fix SharePoint oversharing?
No. It can identify risks and recommend action, but administrators and site owners must review and remediate access.
Can it control personal AI tools?
In supported scenarios, Purview can monitor or block sensitive data shared with unmanaged AI services. It is not universal coverage, so policy and training remain essential.
Get in touch with Northern Star for a practical Microsoft 365 and Copilot governance review before existing access problems become AI-powered data exposures.
