Category Archives: Security

Automating Sites.Selected permissions provisioning

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Scenario

You administer Microsoft 365 SharePoint Online. Part of your daily activities is providing Microsoft Graph and SharePoint Sites.Selected API permissions to other users (developers).

In Aug/Sep 2023 Microsoft pushed an update that prevents site collection admins to create or update an Azure Access Control (ACS) principal (that was the way most of developers used to get Client Id and Client secret to access SharePoint site). So your users are probably getting something like Your SharePoint tenant admin doesn’t allow site collection admins to create or update an Azure Access Control (ACS) principal message attempting to create or update SharePoint App-only principal at AppRegNew.aspx or AppInv.aspx pages. Here are more details on the issue.

Microsoft and MVPs shared some technique how to provide Sites.Selected API permissions, but dealing with scripts manually, elevating individual permissions every time you need to run the script – it all takes time and not very efficient. More and more devs are reaching you on the app. So you want to automate this process.

Solution

Solution architecture

My way to automate it includes:

  • SharePoint list as a frontend
    here you can accept intake requests, organize approval workflow and display automation results
  • Azure Function App as a backend
    here will be your PowerShell script hosted that runs on scheduled basis and takes care of actual permissions provisioning

Solution details

High-level, getting application permissions to some specific SharePoint site is a two-step process:

  1. get application registration in Azure and properly configure it
  2. get permissions for this application to a specific SharePoint site

For the first step – check this and this articles. I’ll focus on the second step below.

You can provide Sites.Selected permissions for the app to a site with

I will be using second one one. Also PnP.PowerShell will be used to get access to SharePoint intake site and read/update requests from SharePoint list and so on.

Azure App Registration

I registered an admin Application in Azure – “SharePoint Automation App”, added Graph Sites.FullControl.All and SharePoint Sites.FullControl.All permissions, then added Microsoft Graph Directory.Read.All permissions and got tenant admin consent:

I generated a self-signed certificate and added it to the app:

This app will be used to call provide permissions, and to connect to the SharePoint front-end.

Users will register their applications in Azure, add Graph Sites.Selected and SharePoint Sites.Selected permissions, got tenant admin consent, then request permissions to the specific site by creating an intake request – new list item.

Front-End SharePoint Site

I created a SharePoint site for automation. This site will play a front-end role for users. I created a list “Sites.Selected” and updated list columns so I have the following fields:

  • Target Site Url
  • Application Id
  • Permissions (read/write)
  • Automation Output

In real-world (Prod) – You can (should) also implement approval workflow as you’d provide permissions for the application to the site only with this site owner approval. The PowerShell code behind should also validate site owner’s consent with app access to site. But for the sake of simplicity I’ll skip this in my demo.

Azure Function App

I created an Azure Function App with the following parameters:
– Runtime stack: PowerShell Core
– Version: 7.2.
– OS: Windows
– Hosting plan: Consumption

And then PowerShell timer-triggered function in Visual Studio Code.

Function requirements.psd1 (it takes a few hours for Azure to install modules; while modules are installing – you might see “[Warning] The first managed dependency download is in progress, function execution will continue when it’s done. Depending on the content of requirements.psd1, this can take a few minutes. Subsequent function executions will not block and updates will be performed in the background.”):

@{
    'Az' = '10.*'
    'PnP.PowerShell' = '2.*'
}

Azure Az module to access other Azure resources. PnP.PowerShell module will be used to access SharePoint.

I will keep my admin Azure registered app in a key vault, so need somehow to let the key vault know that this specific app can access this specific credentials. So I enabled system assigned managed Identity for the Function App:

MS: “This resource is registered with Azure Active Directory. The managed identity can be configured to allow access to other resources…”.
I’m going to use an object (principal) Id of this function to grant access to keyvault.

Azure key vault

Surely we do not hard-code app secrets. So we need a key vault o store app credentials.

I created a key vault under the same resource group in Azure and named it “SharePointAutomationDemo”. Then I added a roles assignment – “Key Vault Secret User” and “Key vault Reader” to the Function App via it’s managed identity:

I also assigned “Key Vault Administrator” role to the user (developer) who will add certificates/secrets to this key vault and develop Azure function code.

Microsoft 365 ownerless group policy to send more than 10,000 notifications

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It is known that a single Microsoft Exchange account is not sending more than 10k emails per day.

It is also know that once activated – Microsoft 365 groups ownerless policy will be sending notifications for all groups in scope to specified number of group members within 24 hours.

The question is: what if there are more than 10,000 notifications to send (e.g. 4,000 ownerless groups and the policy is configured to send notification to 3 members per group – that gives us 12,000 notifications to send)? Would the policy send 10k notifications and the rest 2k notifications the next day?

I’m conducting an experiment. I created 10k groups in my lab tenant with one owner and 3 random members. Then I configured a policy that is sending notification to a 3 most active members (in this case – random members). And then I made all these groups ownerless by deleting the single owner Id from Azure AD (Microsoft Entra).

Here is what I got from users perspective:

useruser groups
number		got messages
day 1		got messages
day 2		got messages
total
1 Roger50121374
2 Dick50391349
3 Bob51083412
4 Bapu49081376
5 Stas49961437
6 David49591377
total10325

Here is what audit log says:

Events “OwnerlessGroupNotified” day 1: 4949
Events “OwnerlessGroupNotified” day 2: 95
Events “OwnerlessGroupNotified” total: 5044
Each event details says 3 members were notified.

It seems like groups are selected by policy in random order.

Massive E-mails sending was started 43 minutes after midnight UTC

“OwnerlessGroupNotified” were logged at the rate of
1925 events during 1-st hour,
2029 events during 2-nd hour,
785 events during 3-rd hour,
176 events during 4-th hour,
26 events during 5-24 th hour,
95 events during next 25-48 hours
so max rate was one event every 3 seconds in the beginning (or 1 e-mail per second) …

TBC…

Your SharePoint tenant admin doesn’t allow site collection admins…

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Scenario

You are trying to register an application at SharePoint site with appregnew.aspx page and you are getting an error or notification message “Your SharePoint tenant admin doesn’t allow site collection admins to create an Azure Access Control (ACS) principal“.

Your SharePoint tenant admin doesn't allow site collection admins to create an Azure Access Control (ACS) principal. Please contact your SharePoint tenant administrator

You are trying to provide ACS-based permissions for an application to SharePoint site with appinv.aspx page and you are getting “Your SharePoint tenant admin doesn’t allow site collection admins to update app permissions. Please contact your SharePoint administrator.”

Your SharePoint tenant admin doesn't allow site collection admins to update app permissions. Please contact your SharePoint tenant administrator

Reason

This is due to a security measures enhancement MC660075 in Microsoft 365 tenant governance recently implemented by Microsoft. According to the update, only tenant administrators can create or update ACS service principal by default.

The root cause for this is that the Microsoft is pushing developers to Azure-registered applications with Sites.Selected API permissions as they are more secure that legacy ACS-based service principals.

Key differences ASC vs Sites.Selected are:

ACS-based SharePoint app/permissionsApps registered in Azure with Sites.Selected API permissions
support authentication with client secret only, secret is valid for 1 year exactlysupport authentication with client secret and certificate, custom expiration time
support granular access to SharePoint at the site-level e.g. to site collection or web or a specific listsupport only access to entire site collection (but Microsoft is working on granular access)
support only classic SharePoint REST API and CSOMsupport both – classic SharePoint REST API and CSOM and Microsoft Graph API
app id (client id) is created via appregnew.aspx at a specific SharePoint site by site collection administratorapp id (client id) is created in Azure portal, API Sites.Selected permissions are configured via Azure portal and require tenant admin consent
permissions for the app to a site are provided at the site by site collection administrator via appinv.aspx pagepermissions for the App to to a specific SharePoint site are provided by SharePoint admin with PowerShell script or Graph API calls

Solution

  1. Register an application in Azure (via Azure portal GUI, PowerShell script or your company’s specific helpdesk/servicedesk request)
  2. Update the app so both – MS Graph API Sites.Selected and SharePoint Sites.Selected permissions are configured and
  3. API permissions must be consented – so you’d seek/request your tenant admin consent
  4. Obtain and upload client certificate (recommended) or generate client secret
  5. Request access for the app to a specific SharePoint site (your SharePoint service admin should be able to do that)
  6. Validate your app has access to the target SharePoint site with PowerShell
  7. Secure your certificate and/or secret

If you are hosting your application in Azure – consider using managed identity.

SharePoint Sites Lookup

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That’s a very common problem in SharePoint world. You are looking for a site owner but there is no tool available for regular user to find who owns the site.

Scenarios.

You get a link to some SharePoint site, but you do not have access to it. You requested access but nobody has responded. You need to find who is the site owner.

(To be continued)

Microsoft Form Blocked due to Potential Phishing

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You are seeing messages “This form can’t be distributed as it is asking for personal or sensitive information. Contact your admin for assistance. Terms of use”

This form can’t be distributed as it is asking for personal or sensitive information. Contact your admin for assistance. Terms of use

or

Form can no longer be accessed. This form has been flagged for potential phishing. Technical details

“Form can no longer be accessed. This form has been flagged for potential phishing. Technical details”

Cause

The reason is: Microsoft enabled automated machine reviews to proactively detect the malicious collection of sensitive data in forms and temporary block those forms from collecting responses. More about it.

Solution

Ask your tenant global or security admin to go to the Microsoft Security Administration (Defender) Alerts:

Microsoft Defender Alert Phishing Form

If your list of alerts is too big – use filter by Policy: “Form blocked due to potential phishing attempt”.

Microsoft Purview - Compliance-Alerts-Filter-By-Policy

To unblock the form or confirm it is phishing – admin should open the alert:

Microsoft Defender Alert Phishing Review this Form

And then click “Review this form“.
“Review the form” opens the page “https://forms.office.com/Pages/AdminPhishingReviewPage.aspx?id=”
where is the form Id.

Then global/security admin can review the form and unblock it or confirm it is phishing:

m365 global/security admin can review the form and unblock it or confirm it is phishing

References

Adaptive scopes Retention Policies Data Lifecycle Purview

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Microsoft recently implemented “Adaptive” retention policies. At step 2 of “Create retention policy” you’ll be asked “Choose the type of retention policy to create”: “A policy can be adaptive or static. Advantage of an adaptive policy will automatically update where it’s applied based on attributes or properties you’ll define. A static policy is applied to content in a fixed set of locations and must be manually updated if those locations change.”

And if you selected “Adaptive” – on the next step you will need to provide the adaptive scope (so at this moment you should already have created your adaptive scopes):

So, let us create your adaptive scopes.
What type of scope do you want to create? SharePoint sites…

And then you’ll have nothing more then set of conditions:

where you can use objects: “Site Url”, “Site Name” and “Refinable String 0″..”Refinable String 99”. Conditions would be “is equal to”, “is not equal to”, “starts with” and “not starts with”. Or you can select “Advanced query builder” and enter KQL query.

Advanced query builder for SharePoint Adaptive Scope

Microsoft 365 Retention Policies SharePoint Adaptive Scopes Advanced Query

External Access Guest Access Microsoft 365 SharePoint Teams

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I will be saving my personal gotchas on Microsoft 365 External Access and Guest Access in SharePoint and Teams

We configure external/guest access in AAD, m365 Admin Center, Teams Admin Center, SharePoint Admin Center, specific Group, Team or SharePoint site.

We can configure external guest access directly, or can configure sensitivity labels and policies in Purview (Compliance Admin Center). Configuring sensitivity labels for sites/groups we configure external guest access settings. Configuring sensitivity labels policies we apply labels.

External access via “All Users” group

Be careful with “All users” group created as part of the process.
Microsoft: “The dedicated All Users group includes all users in the directory, including guests and external users.” And indeed, “All Users” group by default include external users.

So here is the scenario: we have a site where external sharing is enabled, and someone is sharing a specific file1 or folder1 with some external users. The other site/group member is sharing another file2/folder2 with “All Users” assuming All Users means all this group member. This gives external users access to file2/folder2.

Remediation

Option 0: remove “All Users” group

Option 1: exclude External users or Guest users from “All Users” group:

(user.userPrincipalName -notContains "#EXT#@")
or 
(user.userType -ne "Guest")

(explained here).

Option 2: schedule a job that removes “All Users” from all sites UIL. Optionally inform site owners not to use “All Users” but use “Everyone except external users”.