How to help clients identify insecure file shares in Microsoft 365. Is permission sprawl leaving your client data exposed to unauthorized users? Dealing with insecure file shares in Microsoft 365 is a persistent challenge, but you can lock them down by following a structured auditing framework. Before we begin, be sure to subscribe to NinjaOne's IT Video Hub and our YouTube channel for more tech content like this. Securing file sharing at the tenant level. Security starts at the tenant level. You must ensure your sharing settings align with your compliance policies. By navigating to the SharePoint admin center's sharing policies, you can restrict external sharing and define default link settings, such as forcing specific people access instead of anyone with a link. This creates a secure baseline for your entire M365 suite. Identifying unauthorized access and permission sprawl. You need clear visibility into your environment to pinpoint risks effectively. Follow these critical steps to pinpoint unauthorized access and reclaim control over your data. Audit SharePoint and OneDrive by running external sharing reports to detect guest users and externally shared files. Scan for non-corporate email domains, full read/write permissions, and unusual sharing patterns. Investigate anonymous links to ensure sensitive data remains protected. Proactive detection with PowerShell and automation. For deeper insights, leverage PowerShell to uncover hidden vulnerabilities and streamline your monitoring. Use the SharePoint Online Management Shell with commandlets like Get-SPOExternalUser for granular insights. Automate discovery by scheduling scripts in the Windows Task Scheduler to run every 30 days. Configure real-time alerts to immediately notify your team of unusual external sharing, mass deletions, or sensitive file access. Building a culture of compliance and ownership. Technical audits are only half the battle. They work best when integrated into your broader governance strategy. Engage department owners to confirm if external permissions remain business-critical. Maintain a centralized review register to track remediation steps and document findings. Use RMM platforms to automate stakeholder communications and simplify QBR preparation and reporting. Effective file share security is a continuous process of auditing, validating, and automating. When you combine tenant-level controls, PowerShell-driven reporting, and stakeholder engagement, you create a strong ecosystem that stops permission sprawl in its tracks. Proactively managing insecure file shares in Microsoft 365 is an effective way to strengthen your overall data privacy and support ongoing governance. For more information, check out our official blog post on how to help clients identify insecure file shares in Microsoft 365, linked in the description below.