Knowing When Sharing Happens
A natural question flowing from the discussion about implementing the SharePoint Online expiring access policy for external users is how administrators know if people use the feature. Equally naturally, the first place to look is the Office 365 or “unified” audit log to see if SharePoint Online generates any helpful events when users extend sharing links.
Unhappily, although SharePoint Online captures a UserExpirationChanged audit event when someone extends a sharing link close to its expiration, the information stored in the event is not enough to easily identify the content the sharing link grants access to. If you look at the sample audit event shown below, the SiteUrl property tells us that this event relates to sharing some OneDrive for Business content. Apart from that, we can see:
- The user principal name of the user who extends the validity of the sharing link (Jane.Sixsmith@office365itpros.com).
- The user principal name of the target user being granted access (Jsmith_yandex.com#ext#@office365itpros.onmicrosoft.com). The form tells us that this is a guest account (JSmith@yandex.com).
It would be nice if the name of the actual folder or document being shared was captured, but that’s not the case.
RecordType : SharePointSharingOperation
CreationDate : 15/11/2021 13:17:04
UserIds : Jane.Sixsmith@office365itpros.com
Operations : UserExpirationChanged
AuditData : {
"AppAccessContext": {
"AADSessionId": "bfe559aa-a811-488b-828d-a1fa90062133",
"CorrelationId": "b45e03a0-50df-3000-73a8-a6b7cbd31cc0"},
"CreationTime": "2021-11-15T13:17:04",
"Id": "5ee7b4d0-97ca-476d-c7ef-08d9a83a37aa",
"Operation": "UserExpirationChanged",
"OrganizationId": "a562313f-14fc-43a2-9a7a-d2e27f4f3478",
"RecordType": "SharePointSharingOperation",
"UserKey": "i:0h.f|membership|1003bffd805c87b0@live.com",
"UserType": "Regular",
"Version": 1,
"Workload": "OneDrive",
"ClientIP": "51.171.212.129",
"ObjectId": "https://office365itpros-my.sharepoint.com/personal/jane_sixsmith_office365itpros_com",
"UserId": "jane.sixsmith@office365itpros.com",
"CorrelationId": "b45e03a0-50df-3000-73a8-a6b7cbd31cc0",
"EventSource": "SharePoint",
"ItemType": "Web",
"Site": "cc191cff-670a-4740-8458-e6067537c747",
"UserAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36 Edg/95.0.1020.44",
"WebId": "551065f1-04a6-4979-8b19-2c8a0c16319f",
"TargetUserOrGroupType": "Guest",
"SiteUrl": "https://office365itpros-my.sharepoint.com/personal/jane_sixsmith_office365itpros_com",
"TargetUserOrGroupName": Jsmith_yandex.com#ext#@office365itpros.onmicrosoft.com
Investigating SharePoint Sharing Events
To see if it was possible to find some other information that would allow me to link the UserExpirationChanged events back to other sharing events, I wrote a script to extract the events from the audit log and parse their content. The results are not what I hoped. You can track the progress of sharing an item through:
- SharingSet: A user shares an item.
- SecureLinkCreated: A sharing link is created for the item. This is what is sent to the recipient.
- UserExpirationChanged: The expiration date for the sharing link is adjusted in line with policy.
- SecureLinkUsed: The recipient uses the sharing link to access the shared content.
The audit records for the first three events often have the same date and time because they occur close together (within milliseconds). For this reason, they can appear in a different order when viewing the report (Figure 1).
In due course, if the sharing link validity is extended further, SharePoint logs another UserExpirationChanged event. The cycle continues until the sharing link expires.
Download the Script
The script isn’t all that interesting. It finds the relevant audit events, extracts information, and reports its findings (you can download the script from GitHub). Unless you focus on UserExpirationChanged events which happen outside the initial creation of sharing links, I don’t think it helps much in terms of understanding the extent of sharing link extensions. However, someone who is smarter than I might be able to tweak the script to derive better results.
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