Category: Productivity
Secure Microsoft 365 browsing
Secure Microsoft 365 browsing means protecting Outlook, SharePoint, and OneDrive sessions from phishing, malicious downloads, and token theft—without slowing teams down.
Quick answer
Legba can isolate browser sessions while your team uses Microsoft 365.
These tools are full of shared links and external content. Isolation helps reduce exposure when users open unfamiliar destinations and downloads that start from Microsoft 365.
This page does not imply an official integration with Microsoft 365—it’s a guide to securing browser workflows around the app.
When you need this
- Your team uses Microsoft 365 in a browser every day.
- You want to reduce phishing, malicious downloads, and session theft without slowing users down.
- You need role-based policies for employees, admins, and contractors.
Last updated
2026-01-29
Common browser risks
- Outlook-delivered phishing that leads to fake Microsoft sign-in pages or consent prompts.
- Malicious SharePoint/OneDrive links used to deliver malware or harvest credentials.
- Token theft and session replay after MFA via proxy-style phishing kits.
- OAuth consent abuse that grants access to mailboxes and files via third-party apps.
- Data leakage from copying sensitive content into untrusted web apps or AI tools in adjacent tabs.
- Risky extension installs that can read and modify web pages and exfiltrate data.
Typical sensitive data in Microsoft 365
- Email content, attachments, and contact directories.
- SharePoint sites and documents.
- OneDrive files and shared folders.
- Teams/Outlook calendar and meeting metadata.
- User identities and session tokens for M365 apps.
- Admin center settings and audit logs (for admins).
Recommended policies by role
IT Admins
- Use separate browser profiles for admin center access vs daily browsing.
- Isolate unknown external links opened from Outlook and SharePoint, especially in high-target teams.
- Restrict download flows from untrusted shares; require scanning and explicit approval to release files to endpoints.
- Lock down extensions and browser permissions via enterprise policy.
Security
- Monitor OAuth grants and suspicious mailbox rules; prioritize alerts that indicate persistence.
- Use isolation for investigating suspicious links and file shares.
- Enforce phishing-resistant MFA for privileged roles and apply strong session controls.
Finance
- Isolate links and attachments from external senders by default.
- Use step-up verification for payment changes and vendor bank detail updates performed via web workflows.
- Restrict downloads from unknown sources; prefer managed file transfer channels.
FAQs
Why are Microsoft 365 users heavily targeted?
Compromising an M365 account often provides access to email, files, and identity signals across the organization—high leverage for attackers.
Does MFA prevent token theft?
It helps, but token theft can occur after MFA in some phishing models. Isolation reduces exposure by changing where untrusted web content runs.
Can isolation break SharePoint workflows?
Most web workflows work, but you should pilot download/upload policies and tune exceptions for business-critical sites and file types.
What’s a simple rollout strategy?
Start by isolating unknown external links and risky file share destinations, then expand as policies stabilize.
References
- Microsoft Learn: Microsoft 365 security documentation — Microsoft
- Cloudflare: Browser Isolation — Cloudflare
- Chrome Enterprise: Policies — Google