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Find SharePoint Documents to Decrypt Before Tenant Divestiture
A reader wanted to know the best way to find a bunch of files protected by a sensitivity label. The scenario is that the organization had divested an operating division. Sites used by that division had protected files that needed to be decrypted before they moved to a new tenant. If this failed to happen, the protected files would be inaccessible in the new tenant because the users signing into that tenant didn’t have the right to access their content. The question therefore is what’s the best way to find SharePoint documents protected by sensitivity labels so that administrators can remove the labels before the divestiture.
Office documents store label information in their file attributes, so the basic task is to search those attributes to find files protected with one or more specific labels. You could try and do the job with PowerShell and the Graph API. For instance, I have a script to report the files in a SharePoint document library, including the labels assigned to files. Another script uses the Unlock-SPOSensitivityLabelEncryptedFile cmdlet from the SharePoint Online management module to remove labels from documents. The two could be combined to find and remove labels from protected files.
The PowerShell approach is viable if the exercise spans several thousand documents in a few sites. Things become more problematic as the numbers scale up. For instance, sites with document libraries configured to apply default sensitivity labels to new documents (requires Office 365 E5 licenses) could accumulate thousands of protected documents in each library.
Using eDiscovery Searches to Find SharePoint Documents Protected by Sensitivity Labels
eDiscovery searches could solve the problem. Microsoft Purview eDiscovery (Premium) supports finding protected content. The documentation says that files “located on a SharePoint or OneDrive account are searchable and decrypted when the search results are prepared for preview, added to a review set in eDiscovery (Premium), and exported.” Figure 1 shows search preview displaying a protected document found by eDiscovery (Premium).
eDiscovery Premium can’t process documents protected by sensitivity labels with user-defined permissions (permissions assigned by the document author when they apply the label to the document) or when user access granted by the sensitivity label has an expiration date. In addition, eDiscovery Premium can’t decrypt files protected by the Azure Information Protection unified labeling client that are subsequently uploaded to SharePoint Online or OneDrive for Business.
Purview eDiscovery (Standard) and content searches can also find items protected with sensitivity labels. However, these solutions do not decrypt the content unless an unprotected document is an attachment for a protected email. That’s OK, because if you find and export the protected files, an Azure Information Protection (AIP) super-user can remove labels from files using the Set-AIPFileLabel cmdlet from the Azure Information Protection module. Although this is feasible, if you’re contemplating processing thousands of documents, I would buy some Office 365 E5 licenses and use Purview eDiscovery (Premium).
Configuring Content Searches to Find SharePoint Documents with Sensitivity Labels
To search for SharePoint files through Microsoft Search or a Purview content search, you use sensitivity label identifiers (GUIDs). The SharePoint Online search schema includes a managed property called InformationProtectionLabelId, which holds the GUID (identifier) for the sensitivity label assigned to a document. You can use this property to search for documents with a specific sensitivity label in SharePoint search or content searches by using the form InformationProtectionLabelId:GUID. For example, InformationProtectionLabelId:2fe7f66d-096a-469e-835f-595532b63560. The search results are trimmed and only display documents whoever performs the search can access.
An alternative approach is to remap the Sensitivity property, which stores the local language value of the label, to one of the 200 customizable RedefinableString managed properties available in SharePoint Online. This approach allows users to search using label names like “Public” and “Confidential,” but the downside is that it’s possible to assign multiple local language values for sensitivity label display names. If this happens, the searches would need to look for all defined values. By comparison, the identifier is unique and immutable, so using label identifiers is a better choice for search criteria.
To find the label identifiers, connect a PowerShell session to the compliance endpoint and run this command:
Get-Label | Format-Table ImmutableId, DisplayName ImmutableId DisplayName ----------- ----------- 2fe7f66d-096a-469e-835f-595532b63560 Public 8b652c9a-a8b7-40ec-bb1a-c5334b1b7fef No Encryption a49e1277-93db-4a2f-8105-43c5196b4fef Non-business use fb0975b2-1ea1-4c3c-850c-e859e690d282 Partner-Accessible Content e42fd42e-7240-4df0-9d8f-d14658bcf7ce General Access
Now create a content search and input the label identifier into the search conditions, prefixed with InformationProtectionLabelId, just like shown in Figure 2:
To search for documents with different sensitivity labels, separate the label identifiers with OR. For example, here’s the Keyword Query Language (KQL) query to find documents with either of two labels created between 19 May 2023 and 23 June 2023:
InformationProtectionLabelId:1b070e6f-4b3c-4534-95c4-08335a5ca610 OR InformationProtectionLabelId:2fe7f66d-096a-469e-835f-595532b63560(c:c)(date=2023-05-19..2023-06-23)
Dealing with Protected Content
Searching for protected files isn’t difficult. The real question is what you do with the files that the search uncovers. Having a bunch of encrypted files (with or without the new and improved encryption cipher) isn’t much good unless you can decrypt them. That’s where most of the problems lie, which is why Microsoft might have included the feature in Purview eDiscovery (premium).
Learn about using sensitivity labels, eDiscovery, and the rest of Office 365 by subscribing to the Office 365 for IT Pros eBook. Use our experience to understand what’s important and how best to protect your tenant.