# How secure is OneDrive? Microsoft’s cloud security explained When you use OneDrive, you store, organise, and share data through Microsoft’s cloud service. How well that data is protected depends not only on technical security measures, but also on the legal and organisational framework behind the service. ## A brief summary of OneDrive security Microsoft protects OneDrive data with several layers of security. Files are encrypted during transfer using [TLS](https://www.ionos.com/en-ie/digitalguide/server/security/tls-transport-layer-security/) and protected at rest with multilayered encryption methods, including AES-256. However, standard OneDrive storage does not provide traditional end-to-end encryption where only users control the encryption keys. Additional features such as two-factor authentication and access controls provide further protection. Overall, OneDrive offers a high level of technical security for personal use and many business scenarios. From a privacy perspective, OneDrive requires a more nuanced assessment. As a U.S.-based provider, Microsoft may be subject to legal access obligations, including under the CLOUD Act. At the same time, Microsoft has expanded data processing within Europe for many enterprise customers through measures such as the **EU Data Boundary**. Whether OneDrive can be used in line with GDPR requirements therefore depends on the specific use case, contractual setup, configuration, and type of data processed. ## What is OneDrive? With OneDrive, you can store and organise your files in Microsoft’s cloud. The service is available on common Windows systems and requires a **Microsoft account**. OneDrive is also included in many Microsoft 365 packages. You can **sync OneDrive files across devices** or limit syncing to selected apps and devices. OneDrive also lets you create automatic backups and use sharing features to collaborate with others on files. ## What encryption does OneDrive use? Detailed information about Microsoft’s OneDrive security measures is available on the [Microsoft support page](https://support.microsoft.com/en-ie/office/how-onedrive-safeguards-your-data-in-the-cloud-23c6ea94-3608-48d7-8bf0-80e142edd1e1 "Microsoft support page"). It is important to distinguish between encryption in transit and encryption at rest. When data is transferred between your device and Microsoft’s servers, OneDrive uses TLS encryption methods. Stored data is also protected at rest. Microsoft uses several methods for this, including drive-level encryption, for example with BitLocker, and file-level encryption based on AES-256. Even with a supercomputer, cracking this type of encryption would take many years. This multilayered security architecture therefore provides a high level of protection against unauthorised access and brute-force attacks. ## Access rights for data in OneDrive Similar to Google Drive, files and folders in OneDrive can be shared with selected people **for viewing, opening, and editing**. You can: - specify whether content can only be viewed or also edited. - share files with specific email addresses or via generated links. - set time limits or add further restrictions, depending on the account or admin configuration. Existing permissions can be adjusted or revoked at any time, helping you stay in control of your data. Microsoft states that **Zero Standing Access (ZSA)** applies to Microsoft’s access rights to your data. This means Microsoft employees do not have permanent access to stored data. Access is only granted in clearly defined exceptional cases, must be justified and approved, and is subject to strict security and control mechanisms. However, an exception applies to U.S. government authorities. Microsoft must comply with valid requests for information from U.S. authorities and grant access to OneDrive data, including under the CLOUD Act. For companies, this means that OneDrive use depends not only on technical access controls, but also on the data protection assessment of possible third-country and government access. ## OneDrive and the CLOUD Act The U.S. CLOUD Act is a law passed in 2018 that significantly expands the access powers of U.S. authorities. U.S. companies such as Microsoft may be required to provide data to U.S. authorities **even if the data is stored on servers outside the United States**. Microsoft must therefore respond to lawful government requests and provide the relevant data. The issue gained additional momentum after the Schrems II ruling by the Court of Justice of the European Union on July 16, 2020, which invalidated the EU-U.S. Privacy Shield. That ruling focused primarily on U.S. intelligence surveillance laws — in particular FISA Section 702 — rather than the CLOUD Act itself. The CLOUD Act governs law enforcement access to data for criminal investigations, while FISA and Executive Order 12333 address national security surveillance. Both represent distinct legal risks for companies storing data with U.S.-based providers, and both should be considered separately when assessing GDPR compliance. Despite this new legal framework and certification, the use of Microsoft services such as OneDrive still requires an individual risk assessment. Companies should review which data is processed, which contractual terms apply, and whether additional technical and organisational measures are needed to ensure an appropriate level of data protection. ## How secure is OneDrive against cyberattacks? In general, Microsoft offers solid and reliable security for Cloud storage, similar to Google and Apple. This is especially true if you use OneDrive **for personal purposes or to back up data that is not business-critical**. OneDrive security measures against cyberattacks and unauthorised access include: - account protection with strong passwords - two-factor authentication (MFA) for additional access security - TLS encryption during data transfer - multilayer encryption for stored data, including AES-256 - controlled access processes based on the Zero Standing Access principle - network isolation, firewalls and physical security in data centres - malware scanning for uploaded files in Microsoft 365 environments - ransomware detection and recovery features, depending on the package - version history and file recovery - Personal Vault for especially sensitive files in personal accounts - granular sharing options for files and folders, such as access restrictions for links - notifications for suspicious sign-in attempts - account recovery using stored security information - access logging and monitoring, especially in business contexts ## Where are OneDrive servers located? Where OneDrive data is stored and processed depends on the specific usage scenario and Microsoft service. Microsoft operates data centres worldwide, including in the U.S., Europe, and Asia. Microsoft completed the EU Data Boundary in February 2025. The initiative was announced in 2021 and has been rolling out in phases since January 2023. This allows customer data and certain personal data from core cloud services to be stored and processed within the EU and EFTA regions. This significantly improves data residency and transparency. From a GDPR perspective, companies should still carefully review which data categories are affected, which Microsoft services are actually used, and whether international aspects may still be relevant in specific support, diagnostic, or legal access scenarios. Tip If the location of your data is especially important to you, it is worth choosing cloud providers with clearly defined server locations within the EU. Services with transparent data processing, European data centres, and clear data protection concepts make it easier to comply with the GDPR and reduce risks related to international data transfers. ## Is OneDrive compliant with the GDPR and EU data protection rules? Whether OneDrive can be used in a GDPR-compliant way **cannot be answered with a blanket yes or no**. Microsoft provides extensive contractual and technical foundations for OneDrive and Microsoft 365, including a Data Processing Addendum, Standard Contractual Clauses, and detailed information on security and compliance. At the same time, OneDrive remains sensitive from a data protection perspective because it is provided by a U.S. company. Under certain conditions, Microsoft may be required to respond to lawful requests from authorities. For companies, this means that they need to consider not only technical security, but also the legal assessment of possible third-country access. Microsoft has improved its data processing practices in recent years. With the EU Data Boundary, data from many European business customers is primarily processed within the EU and EFTA. However, actual data processing still depends on the specific service, configuration, and usage scenario. For GDPR-compliant use, companies must therefore **implement suitable technical and organisational measures**. These include a data processing agreement, clear authorisation concepts, multi-factor authentication, and transparent information for data subjects. ## Is OneDrive secure for business and compliance? For businesses, OneDrive needs to be assessed carefully from a data protection and compliance perspective. Microsoft provides security and compliance features as well as contractual foundations such as the Data Processing Addendum and Standard Contractual Clauses. However, responsibility for using OneDrive in compliance with data protection requirements remains with each company. As a U.S.-based provider, Microsoft is subject to legal access obligations under the CLOUD Act. This means it cannot be completely ruled out that U.S. authorities may access data under certain conditions, even when the data is stored in the EU. Organisations in Ireland and other EU countries should take this into account as part of their GDPR compliance and data protection assessments. European regulators have repeatedly raised concerns about the use of Microsoft 365 in sensitive environments, particularly regarding international data transfers and third-country access to personal data. Companies that use OneDrive should pay particular attention to the following points: - concluding a data processing agreement or Microsoft’s Data Processing Addendum - clarifying the legal basis for processing personal data - providing transparent information in the privacy policy about the type, scope, and purpose of data processing - reviewing third-country transfers and the safeguards used - implementing technical and organisational measures such as multi-factor authentication and access control concepts Under Article 28 GDPR, companies must conclude a **data processing agreement with Microsoft** if personal data is stored in OneDrive for business purposes. This agreement should define: - which personal data Microsoft receives - why the data is shared with Microsoft - how long Microsoft stores the data - which rights, obligations, and liability limitations apply If you want to **use OneDrive in compliance with the GDPR**, follow these steps: - assess the risks of third-country transfers, for example as part of a Transfer Impact Assessment - review Microsoft’s current contractual documents and compliance documentation - define internal policies for data classification and access - implement logging, monitoring, and access control concepts ## What are some alternatives to OneDrive? If you have doubts about Microsoft’s data protection measures and are still wondering whether OneDrive is secure enough for your needs, it is worth comparing different cloud providers. This gives you an overview of the features and security levels offered by available OneDrive alternatives. European and [German cloud providers](https://www.ionos.com/en-ie/digitalguide/server/tools/irish-cloud-providers/) are popular alternatives to OneDrive. They often offer stricter data residency options and can make it easier to meet European data protection requirements. Providers with a high level of data protection and server locations designed to support GDPR compliance include IONOS HiDrive and Secure Cloud, among others. This is a markdown version of: [https://www.ionos.com/en-ie/digitalguide/server/tools/how-secure-is-onedrive/](https://www.ionos.com/en-ie/digitalguide/server/tools/how-secure-is-onedrive/) for AI/LLM consumption.