How to Report Audit Events Generated for Sensitivity Labels

Understand How People Use Sensitivity Labels to Protect Office Documents

If you enable support for sensitivity labels in SharePoint Online and OneDrive for Business (and you should), most of the previous frustrations that organizations have experienced in dealing with protected go away. Protected (encrypted) content can be indexed and found by eDiscovery, co-authoring is supported (with Office Online), and so on. And very importantly, Office 365 captures audit events when people apply, remove, or change sensitivity labels with Office documents.

Originally, only sensitivity label actions performed by the Office Online apps were captured. This is fine, but most user interactions with Office documents occur through the desktop apps. The gap in coverage is closing and the latest versions of the Microsoft 365 apps for enterprise (aka Office click to run) now create audit records when they apply or remove labels from documents. I’m using version 2012 – current channel preview (build 13350.20316) as the basis for this article, but I can see that audit records have been generated since mid-December.

Although the latter part of December is a period of low work activity, the number of events captured since compared against previous months confirms the view that desktop apps are used more heavily to generate documents, spreadsheets, and presentations. At least, in my tenant.

Separate Audit Events

Nice as it is to have the additional insight into the use of sensitivity labels, it’s regrettable that Microsoft did not use the same operation names when generating audit records for the desktop apps as they do for the online apps. The operation is the name of an auditable action.

It’s possible that the logic here is that the actions originate in two different sources and the different operations mean that administrators can conduct precise audit searches to find records for either the desktop or online apps – or both.

The new operations are:

  • SensitivityLabelApplied: A sensitivity label is applied to an Office document. This operation is also used when capturing a record for the application of a label to a SharePoint site. The two can be distinguished by the record type, which will be either SensitivityLabeledFileAction (for Office) or SharePoint. Events are recorded when users apply sensitivity labels to Outlook messages, but not for messages protected by OME. OWA and Outlook mobile clients don’t currently generate audit events when users label messages.
  • SensitivityLabeledFileOpened: An Office document with a sensitivity label is opened by a desktop app.
  • SensitivityLabelRemoved: A sensitivity label is removed from an Office document.
  • SensitivityLabeledFileRenamed: An Office document with a sensitivity label is renamed to become a new file. This event is also logged when a labelled file stored on a local device (not a copy synchronized by OneDrive) is edited.

As in many cases with Office 365 audit log records, the new events need to be parsed out before they’re useful. This is reasonably easy to do with PowerShell, albeit at the need to examine and interpret the payload content of each type of event.

Reporting Audit Events

Seeing is believing and it’s always easier to understand how things work when you have a practical example. I’ve written a script to grab all the events for sensitivity labels for the last three months and create a report. Each of the event types is unpacked and interpreted to make it clear what the event means. The output is a CSV file which can be analyzed in whatever way you wish. Or you can examine the output on-screen through the Out-GridView cmdlet (Figure 1).

Reviewing audit information for actions involving sensitivity labels
Figure 1: Reviewing audit information for actions involving sensitivity labels

The script is available in GitHub. You’ll need to connect to the Exchange Online management module and the security and compliance endpoint to run the cmdlets in the script. The compliance endpoint is used to fetch the list of sensitivity labels defined in the organization and create a hash table of GUIDs/identifiers (the keys) and label names (values). Some audit events contain label names but it’s more typical to only find a label identifier recorded, so lookups against the hash table translate identifiers into label names.

As you can see from the output, in my tenant most audit records are recorded when an Office desktop app opens a protected file:

Job complete. 370 Sensitivity Label audit records found for the last 90 days

Labels applied to SharePoint sites:  51
Labels applied to new documents:     45
Labels updated on documents:         5
Labeled files renamed:               29
Labeled files opened (desktop):      200
Labels removed from documents:       40
Mismatches detected:                 0

Report file written to C:\temp\SensitivityLabelsAuditRecords.csv

In this case, no mismatches are noted between the label applied to a site (container management) and those assigned to documents stored in the site. My users might just be learning how to label documents properly!

We write tons of PowerShell scripts to check out how Office 365 really works and understand where any fault lines might be. Our GitHub repository is available to all. Even better, we explain how to use our scripts and other PowerShell commands to manage Office 365 in the Office 365 for IT Pros eBook.

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