Category Archives: Security

Ownerless Microsoft 365 groups, teams and sites Q&As

(WIP)

Any team in Microsoft Teams or a Microsoft 365 group or a SharePoint site must have an owner. Otherwise to whom we communicate on site/group/team retention policy, content classification etc. Who will be responsible for team/site/group content and configuration and who will provide access to this site for other users.

MS: A team in Microsoft Teams or a Microsoft 365 group and its related services can become ownerless if an owner’s account is deleted or disabled in Microsoft 365. Groups and teams require an owner to add or remove members and change group settings.

Recently Microsoft implemented a new feature: a policy that automatically asks the most active members of an ownerless group or team if they’ll accept ownership. Very important feature. TY Microsoft!

But still we have some questions.

Q: I support a large Microsoft 365 environment and we already have hundreds of ownerless groups. I’m concerned how users might react, if support teams are ready for new type of tickets etc. Implementing the policy in test/stage environment does not make much sense, since there are no really active users etc. So, can I pilot or test this policy in production within a small amount of users or ownerless groups before applying to all groups in the environment.

A: Yes, you can do a test or pilot implementation in production limiting the impacted users or groups.
– if you need lo limit users who will be getting notifications – during Step 1 “Notification Options” under “Specify who can receive ownership notifications” you can select “Allow only certain active members” and under “Specify security groups to ‎allow members‎” you can select a security group – so only members from the specified security group will be sent ownership request.

Q: I know the policy is applied to Microsoft 365 groups only. But I have many standalone sites with no owners (no site collection administrators). How do I deal with ownerless SharePoint sites?

A: You have at least two options:
1) Promote site “Full Control” users to site administrators
2) Convert standalone sites to Microsoft 365 group based sites

References

Testing Sites.Selected SharePoint and MS Graph API

Sites.Selected MS Graph API permissions were introduced by Microsoft in March 2021. One year later, in 2022 they added SharePoint Sites.Selected API permissions.

Azure registered app with SharePoint and MS Graph API Sites.Selected permissions

Why is this so important? Because MS Graph API for SharePoint is still limited and cannot cover all possible needs. I’d estimate: 90% of applications use SharePoint CSOM, so developers have to use AppInv.aspx to provide permissions for their applications to SharePoint API.

But from this moment – having SharePoint API permissions in MS Graph – in theory – we can fully rely on permissions provided in Azure and – in theory – this should allow us disable SharePoint-Apps only principal:

Set-SPOTenant -DisableCustomAppAuthentication $true

My math professor taught me: “before trying to find a solution – ensure the solution exists.” So let us test:

Are we really able to work with a specific SharePoint site using MS Graph and SharePoint API Sites.Selected permissions provided via Microsoft Azure?

What will happen with our new/legacy applications if we disable SharePoint app-only SPNs (DisableCustomAppAuthentication)?

I’m getting controversial test results… maybe PnP.PowerShell 1.10 is not fully support SharePoint Sites.Selected API.

Tech Wizard (Sukhija Vikas) on March 20, 2022 in the article “SharePoint and Graph API APP only permissions for Selected Sites” suggests using pre-release (AllowPrerelease).

So please ignore the following for a while.

Meantime I’ll test providing SharePoint Sites.Selected API permissions via Graph API call.

(wip) Test set #1: Certificate vs Secret

DisableCustomAppAuthentication: $false (SP-app-only spns are enabled).
All applications have “write” access provided to a specific site only.
Connecting with Connect-PnPOnline and then test access with Get-PnPSite

App / Get-PnPSiteSecretCertificate
ACS based (Azure+AppInv)OKThe remote server returned an error: (401) Unauthorized.
MS Graph API Sites.SelectedThe remote server returned an error: (403) Forbidden.The remote server returned an error: (401) Unauthorized.
SharePoint API Sites.SelectedOKOK
MS Graph API + SharePoint API Sites.SelectedAccess is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))OK
App with no permissionsThe remote server returned an error: (403) ForbiddenThe remote server returned an error: (401) Unauthorized

(wip) Test set #2: Sites.Selected SharePoint vs MS Graph (secret)

  • DisableCustomAppAuthentication = $false
    (SP-app-only spns are enabled).
  • All applications have “write” access provided to a specific site only.
  • Using Client Secret (not a certificate)
  • Using PnP.PowerShell
Action/ViaSharePoint + MS Graph
Sites.Selected
“secret”		SharePoint
Sites.Selected
“secret”		MS Graph
Sites.Selected
“secret”
Connect-PnPOnlineWARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.WARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.WARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.
Get-PnPSiteOKOKThe remote server returned an error: (403) Forbidden.
Get-PnPListOKOK
Get-PnPListItemOKOK
Set-PnPSiteAttempted to perform an unauthorized operation.
Set-PnPListAttempted to perform an unauthorized operation.
Set-PnPListItemOKOK
New-PnPListAccess is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
Add-PnPListItemOK

(wip) Test set #3: Read vs Write vs FullControl

DisableCustomAppAuthentication = $false
(SP-app-only spns are enabled).
All applications have Sites.Selected SharePoint and MS Graph API permissions.
Using Client Secret (not a certificate)
Using PnP.PowerShell

ReadWriteFullControl
Connect-PnPOnlineWARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.WARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.WARNING: Connecting with Client Secret uses legacy authentication and provides limited functionality. We can for instance not execute requests towards the Microsoft Graph, which limits cmdlets related to Microsoft Teams, Microsoft Planner, Microsoft Flow and Microsoft 365 Groups.
Get-PnPSiteAccess is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
Get-PnPListAccess is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
Get-PnPListItem
Set-PnPSite
Set-PnPList
Set-PnPListItem
New-PnPList
Add-PnPListItem

(wip) Test set #5: Certificate vs Secret

C#, SharePoint CSOM, PnP.Framework

Findings

PnP.PowerShell Get-, Grant-, Set- and Revoke-PnPAzureADAppSitePermission cmdlets require Azure App with MS Graph Sites.FullControl.All app permissions (otherwise it says “Access denied”) and authentication via certificate (otherwise it says “This cmdlet does not work with a ACS based connection towards SharePoint.”)

The same actions – managing permissions for the client app to the specific site collections – could be done via Microsoft Graph Sites Permissions API using just secret-based authentication.

If an azure app does not have Sites.Selected API permissions configured – “Grant-PnPAzureADAppSitePermission” works as expected – no error messages – the output is normal – as if Sites.Selected API permissions were configured in the app. The same for Get-, -Set and Revoke-. Permissions provided for the app to the site are not effective though: Connect-PnPOnline works well, but all other commands – starting from Get-PnPSite – returns “The remote server returned an error: (403) Forbidden.”

If an app have no permissions to SharePoint – “Connect-PnPOnline” works ok, but “Get-PnPSite” return an error: “The remote server returned an error: (403) Forbidden.”

Set-PnPAzureADAppSitePermission gives an error message “code”:”generalException”,”message”:”General exception while processing”
if the site is not specified.

AppInv is not working?

Error: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

References

Testing environment

  • Microsoft 365 E5 Dev environment
  • PowerShell 7.2.2
  • PnP.PowerShell 1.10
  • “write” permissions to the specific sites for client apps were assigned via PnP.PowerShell

Connecting to SharePoint Online programmatically: Secret vs Certificate

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.

Scenario

You have an application that needs access to Microsoft 365 SharePoint Online site/list/documents. Application is running without interaction with users – e.g. unattended, as daemon job.

There are two options you can authenticate to Microsoft 365 – with the secret or with the certificate. Authenticating with certificate is considered more secure.

Questions

  • What happens if SharePoint-Apps only principal is disabled
    (i.e. ‘set-spotenant -DisableCustomAppAuthentication $true’ )?
  • Why I’m getting 401 error when authenticating to SPO?
  • Why I’m getting 403 error when authenticating to SPO with secret?
  • What permissions to I need to work with SPO?

Findings

Note: we will use PowerShell 7.2 and PnP.PowerShell 1.9 to illustrate it.

Disabled SharePoint-Apps only principal

If SharePoint-Apps only principal is disabled in your tenant
(i.e. ‘Get-PnPTenant | select DisableCustomAppAuthentication’ returns $true ), then the only way you work with SPO from code is:

  • an App registered in Azure
  • API permissions provided via Azure (MS Graph, SharePoint)
  • Certificate is used

In all other cases (even your Connect-PnPOnline command complete successfully) – you will be getting error 401 (unauthorized) when trying Get-PnPTenant or Get-PnPTenantSite or Get-PnPSite

Enabled SharePoint-Apps only principal

If SharePoint-Apps only principals are enabled in your tenant
(i.e. ‘Get-PnPTenant | select DisableCustomAppAuthentication’ returns $false ), then you have two options to work with SPO from code:

  • Azure App with a secret (Client Id + Client Secret) and permissions to SharePoint provided via SharePoint ( AppInv.aspx )
  • Azure App with a certificate (Client Id + Certificate) and permissions provided via Azure (Microsoft Graph and/or SharePoint)

Error 401 while accessing SharePoint Online with PnP

(Get-PnPTenant, Get-PnPTenantSite)

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 to the app.

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

Connect-PnPOnline with a certificate stored in Azure Key Vault

Scenario

You run some PnP PowerShell code unattended e.g. daemon/service app, background job – under application permissions – with no user interaction.
Your app needs to connect to SharePoint and/or Microsoft Graph API. Your organization require authentication with a certificate (no secrets). You want certificate stored securely in Azure Key Vault.

Solution (Step-by-step process)

  1. Obtain a certificate (create a self-signed or request trusted)
  2. In Azure where you have Microsoft 365 SharePoint tenant
    1. Create a new Registered App in Azure; save App (client) id, Directory (Tenant) Id
    2. Configure App: add MS Graph and SharePoint API application (not delegated) permissions
    3. Upload the certificate to the app under “Certificates & secrets”
  3. In Azure where you have paid subscription (could be same or different)
    1. Create an Azure Key Vault
    2. Upload certificate to the Key Vault manually (with GUI)
  4. While you develop/debug your custom daemon application at your local machine
    1. Provide permissions to the Key Vault via Access Control and Access Policies to your personal account
    2. Connect to Azure (the one where your Key Vault is) running Connect-AzAccount
      – so your app can get a Certificate to authenticate to SharePoint Online
  5. For your application deployed to Azure (e.g. Azure Function App )
    1. Turn On managed identity (Your Function App -> Identity -> Status:On) and Save; notice an Object (Principal) Id just created
    2. Provide for your managed identity principal Id permissions to the Key Vault via Key Vault Access Policies, so when your daemon app is running in the cloud – it could go to the key Vault and retrieve Certificate

Here is the sample PowerShell code to get certificate from Azure Key Vault and Connect to SharePoint with PnP (Connect-PnPOnline):

# ensure you use PowerShell 7
$PSVersionTable

# connect to your Azure subscription
Connect-AzAccount -Subscription "<subscription id>" -Tenant "<tenant id>"
Get-AzSubscription | fl
Get-AzContext

# Specify Key Vault Name and Certificate Name
$VaultName = "<azure key vault name>"
$certName = "certificate name as it stored in key vault"

# Get certificate stored in KeyVault (Yes, get it as SECRET)
$secret = Get-AzKeyVaultSecret -VaultName $vaultName -Name $certName
$secretValueText = ($secret.SecretValue | ConvertFrom-SecureString -AsPlainText )

# connect to PnP
$tenant = "contoso.onmicrosoft.com" # or tenant Id
$siteUrl = "https://contoso.sharepoint.com"
$clientID = "<App (client) Id>" # Azure Registered App with the same certificate and API permissions configured
Connect-PnPOnline -Url $siteUrl -ClientId $clientID -Tenant $tenant -CertificateBase64Encoded $secretValueText

Get-PnPSite

The same PowerShell code in GitHub: Connect-PnPOnline-with-certificate.ps1

References: