Tag Archives: Security

Sensitivity labels in Microsoft Teams, Microsoft 365 groups, and SharePoint sites

Note: When you follow instructions provided by Microsoft, beware that “Connect-AzureAD” works only in Windows .net framework – i.e. PowerShell 5.1.
if you try to run it in PowerShell 7 – you can get “Connect-AzureAD: One or more errors occurred. (Could not load type ‘System.Security.Cryptography.SHA256Cng’ from assembly ‘System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’.)” Error.
(check Connect-AzureAD Could not load type ‘System.Security.Cryptography.SHA256Cng’ from assembly)

Configuring Sensitivity Labels

Sensitivity labels are configured under Microsoft Purview (Compliance Center), Solutions, Information Protection. You’d need a global admin or “Compliance Administrator” or “Azure Information Protection Administrator” (?) role:

Since we are talking sensitivity labels for SharePoint Sites (not documents), we define label scope as “Groups and Sites”: “Configure privacy, access control, and other settings to protect labeled Teams, Microsoft 365 Groups, and SharePoint sites.”

Then we define which protection settings for groups and sites we should configure on the next steps:
– Privacy and external user access settings – Control the level of access that internal and external users will have to labeled teams and Microsoft 365 Groups.
– External sharing and conditional access settings – Control external sharing and configure Conditional Access settings to protect labeled SharePoint sites.

If we selected previously “Privacy and external user access settings” – now we need to select group/team privacy (These options apply to all Microsoft 365 Groups and teams, but not standalone sites). When applied, these settings will replace any existing privacy settings for the team or group. If the label is removed, users can change privacy settings again. You can also allow external user access – if group owner will be able to add guests:

Next step – define external sharing and conditional access settings. Specifically, if the content of the SharePoint site can be shared with Anyone (anonymously) or with authenticated users (new or existing) or no external sharing is allowed:

And you can either control the level of access users have from unmanaged devices or select an existing authentication context to enforce restrictions:

Configuring sensitivity labels policies

Sensitivity label policy is basically which label should be available to apply for what users and some other settings like
– do users need to provide justification before removing a label or replacing it with one that has a lower-order number or
– will users be required to apply labels and optionall the default label

View existing sensitivity labels

“Global reader” role allows view existing sensitivity labels configuration:

Wording would be a little different, but all aspects of the label configuration will be mentioned. E.g. when editing GUI says label scope is “Groups & sites”, read-only label summary defines Scope as “Site, UnifiedGroup”.

Gotchas

Site sensitivity label is applied to site collection only and cannot be applied to subsite (web object).

Applying sensitivity labels programmatically

To apply a label to a m365 group or Teams site with a group behind: MS Graph API support only Delegated permissions.

Set-PnPSiteSensitivityLabel” works in the current site context.
Description says “If the site does not have a Microsoft 365 Group behind it, it will set the label on the SharePoint Online site and will not require Microsoft Graph permissions and will work with both delegate as well as app only logins.”
In fact (7/22/2022) app permissions are not working. This cmdlet can assign label to a standalone or a group-based site only with delegated permissions.

Set-PnPTenantSite” allows you to remove or apply site sensitivity label to both standalone and group-based sites with app permissions. Furthermore, group and team settings respect this. I.e. if you apply label to a group-based site – group will pick this up.

Channel sites should inherit sensitivity label from root site.
I’m not sure if it’s a bug but
– when you create a team and select sensitivity label as part of team creation process – all the channel sites you create after (Private or Shared) will inherit sensitivity label immediately
– when you apply sensitivity label to an existing team – with existing channel sites – in this case Private channel sites inherit team sensitivity label immediately, but with Shared channel sites it’s strange: GUI shows sensitivity label assigned, but site object model does not.

References

Search Unified Audit Log Daemon Job

How to run “Search-UnifiedAuditLog” in unattended way, i.e. non-interactive.
What are the minimal permissions required?

The PowerShell code:

$clientId = ""
$cPwd = ConvertTo-SecureString -String "" -AsPlainText -Force

$cPath = ""C:\Users\UserName\Certificates\Cert.pfx""
$organization = "contoso.onmicrosoft.com"

Connect-ExchangeOnline -CertificateFilePath $cPath -CertificatePassword $cPwd -AppID $clientId -Organization $organization

[DateTime]$start = [DateTime]::UtcNow.AddMinutes(-45)
[DateTime]$end = [DateTime]::UtcNow
$resultSize = 1000

$results = $null
$results = Search-UnifiedAuditLog -StartDate $start -EndDate $end -ResultSize $results.Count
$results | Select-Object RecordType, CreationDate, UserIds, Operations -First 3

Disconnect-ExchangeOnline -Confirm:$false

Troubleshooting

The error “The term ‘Search-UnifiedAuditLog’ is not recognized”:

Search-UnifiedAuditLog: C:\scripts\PowerShell.auth\Search-AuditLog-w-App.ps1:16:12
Line |
16 | $results = Search-UnifiedAuditLog -StartDate $start -EndDate $end -Re …
| ~~~~~~
| The term 'Search-UnifiedAuditLog' is not recognized as a name of a cmdlet, function, script file, or executable
| program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.

means a proper administrative role (e.g. “Exchange administrator”) is not assigned.

References

Track SharePoint App-only Service Principals in Microsoft 365

Update (May 2023):
You can use Get-PnPAzureACSPrincipal to returns the lists of all Azure ACS principals installed in your Tenant including subsites.

Scenario

Developers in the organization can use both – Azure Apps and SharePoint Apps to work with SharePoint sites in their “daemon” applications.

It is recommended to use Azure apps so, you want to know – what are SharePoint Apps registered and their owners, who registered SharePoint Apps. Eventually you would disable SharePoint Apps-only principal but before that you’d move Devs from SP-App-only to Azure App (see Disable Custom App Authentication).

(SharePoint App-only service principals aka SP-App-Only are SPN or App registered from within SharePoint using AppRegNew.aspx system page).

One of the approaches is to track Apps/Owners with Unified Audit Log

Use Unified Audit Logs

The following PowerShell code:

$operations = 'Add service principal.'
$recordType = 'AzureActiveDirectory'
Search-UnifiedAuditLog -StartDate $start -EndDate $end -ResultSize $resultSize -Formatted -Operations $operations -RecordType $recordType

returns events with operation = ‘Add service principal.’ Nice, but…
if an app was registered in Azure – event contains an UPN under UserIds property:

Unfortunately, in case with registering app in SharePoint, an audit log event will be like:

i.e. UserId registerd is “spo_service@support.onmicrosoft.com”, so we do not know who registered a SharePoint-only app

In theory – we could use events recorded immediately before and after “Add service principal” event to track a user and site who has registered a SharePoint-only app… But for me it seems like too complicated for automation.

Instead we can do simple search through audit log for events “AppRegNew.aspx page visited”. This gives us a good approximation of who registered SP-App-only principal. Worst scenario – we reach more people than we really need (including those who started registering sp-app-only but did not complete) but all of them would be definitely our target auditory.

Consider the following code:

$freeText = "appregnew"
$operations = 'PageViewed'
$recordType = 'SharePoint'

$results = Search-UnifiedAuditLog -StartDate $start -EndDate $end -ResultSize $resultSize -FreeText $freeText -Operations $operations -RecordType $recordType 

this would give you all users who loaded “/_layouts/15/appregnew.aspx” page

Update: Sites.Selected API MS Graph permissions was introduced by Microsoft in 2021. It was a good move towards site-level development, but still developers were limited with only what MS Graph API provides for SharePoint dev.
So devs had to use AppInv.aspx at site level to provide ACS permissions to their apps to be able to use SharePoint CSOM and REST APIs.
Recently Microsoft introduced Sites.Selected SharePoint API permissions for registered Azure Apps! So now devs should be fully happy without ACS-based permissions.

References

How to Find Content Shared with Everyone in SharePoint and Teams

There is a known problem in SharePoint – complicated permissions system. Site owners/administrators provide access, site contributors upload documents and nobody knows – who has access to their sites. As a result – sometimes sensitive documents become overshared (over-exposed).

The biggest concern is sites content shared with “Everyone”. How do we find sites shared with “Everyone” in a large Microsoft 365 environment?

NB. When I say “shared with Everyone” – I actually mean 3 possible “everyone” logins:

  • Everyone
  • Everyone except external users
  • All users

Approach #1 (Brute force)

We can get full permissions report at tenant level (or permissions provided only to “Everyone”). There are 3-rd party tools (e.g. ShareGate, SysKit, AvePoint, Metalogix etc.), or you can run PowerShell script…

Sounds easy? Well, if you have less than 1000 sites – probably it will work. But if your environment is 10K+ sites – it will take forever. Permission report might run hours for an average site with site/subsite, list/library and list item details level. So the approach will not work for large enterprise environments.

One might say – we can limit report with root web permissions only to get it faster. But this would not be accurate. And what is not accurate in the IT security – lead to even bigger risks. So, we need report detailed up to every item level deep, as even one file with sensitive info shared with everyone can cause security issue. (3-rd party tools usually by default limit it to libraries level.)

Ok, if this approach is not really working – what’s working?

Clever idea: why do we need to iterate through all the tenant documents/items if all the content is already crawled by search? Search is also respect permissions. Can we just use search to get files shared with Everyone? Let us see.

What if we use some dummy user account with no specific permissions provided and no group membership and try to search content on behalf of that account. The idea is if this user can see data – it means that data is open for everyone.

Check this and this articles. Can we get results programmatically (e.g. with PowerShell)? Can we use Microsoft Graph search API? Sure.
Check this article “How to search against SharePoint Online Content with Microsoft Graph search API with PowerShell”.

But! We have some problems here.

Search Problem #1. Again, for small environments or if there are not much “Open” sites – it would work. But for large enterprise environments the problem is the same as in “brute force”. Search returns too many results – it’ll take weeks to get all of them. (There are team sites “legally” shared with everyone, public Office 365 group based sites, communication sites… ).

Search Problem #2. Even if we get all search results – we do not know – at what level permissions are provided to everyone. So we will need to build list of sites based on the search results – ant then still need to run permissions report against these sites.

Search Problem #3. We are getting results with paging. But recently Microsoft started limiting number of returning results. E.g. your search request result might say like “there are 3659735 total hits” but after result number 1000 it just stops returning anything, even with paging.

Approach # 3 Hybrid

The idea: why do we need to get all search results if even one result from a site would be enough to add the site to the list of sites require permissions review. In other words, we do not need all results from site, we only need one to know the site is open.

So, consider (imho, the best) approach (Solution):

  1. You get list of all sites in tenant.
  2. You run search request against each site in the loop
    (e.g. consider KQL option “Site: https://yourTenant.SharePoint.com/sites/YourSite”.
    If at least something found in the site – add the site to the “Open Sites” list.
    With this approach you will get list of sites shared with “Everyone…” in a couple of minutes.
  3. Run permissions report against this shortlist

Note: consider there are resources like “Styles Library” shared with everyone by default.

Note: You can refine the list you get at step 1 – e.g., excluding sites connected to public teams or known communication sites…

Note: consider implementing sensitivity labels. At least you can start with high-sensitive sites. Site owners/member will know – what kind of site they are working on.

Pros and cons of the Approach # 3 Hybrid

Pro: the only fast and accurate enough to rely on

Con 1 : crawling and indexing takes time, so search-based reports can miss recent changes in data and permissions

Con 2: this approach cannot be automated (since we need an interactive authentication).

How to communicate to site owners

The Next step would be “How to let site owners know that there are resources shared with Everyone… on their sites”.

References