Python connect to SharePoint via Graph API with Delegated Permissions

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Below is the sample Python code to authenticate against Microsoft 365 as current user with MSA library and to call Microsoft Graph API – specifically get SharePoint Site, get Site lists with requests library.

But first, you have to have an App Registration in Azure (Entra ID) with delegated permissions consented and authentication configured.

Delegated Permissions

If your solution needs access to all SharePoint sites – consider Sites.FullControl.All or Sites.Manage.All or Sites.ReadWrite.All or Sites.Read.All depending on access level you need. Effective permissions would be a min from both – permissions configured for app registration and permissions current user have. Once consented at the app registration – these permissions will work right away.

If your solution needs access to one (or a few) SharePoint sites – consider Sites.Selected API permissions as it will scope down access to only sites that are required for your solution to work. Remember, Sites.Selected API permissions, even consented at the app registration, does require second step – SharePoint admin should provide (read or write or manage or fullcontrol) permissions for the app registration to a specific site or sites.

Authentication

You’d also need to configure authentication blade. How? It depends on the kind of application you are building etc. For example for native apps I do:
– add platform – “Mobile and Desktop app”
– select “https://login.microsoftonline.com/common/oauth2/nativeclient”
– select “msal096fd951-7285-4e4f-9c1f-23a393556b19://auth (MSAL only)”
– add custom Redirect URI: “http://localhost”

This config works for Python code below

Python Code

You’d need to install/import the libraries: json, configparser, msal, requests

Here is the code:

import json
import configparser
import msal
import requests

config = configparser.ConfigParser()
config.read('config.cfg')
client_id = config.get('delegated','clientId')
authority = config.get('delegated','authority')
scopes = config.get('delegated','scope').split()
siteId = config.get('delegated','siteId')
print( client_id)
print( authority)
print( scopes)
print( siteId)

global_token_cache = msal.TokenCache()
global_app = msal.PublicClientApplication(
    client_id,
    authority=authority,  # For Entra ID or External ID
    token_cache=global_token_cache,  
    )

def acquire_and_use_token():
    # The pattern to acquire a token looks like this.
    result = None
    result = global_app.acquire_token_interactive(scopes)

    if "access_token" in result:
        print("Token was obtained from:", result["token_source"])  # Since MSAL 1.25
        # print("Token acquisition result", json.dumps(result, indent=2))
        return result["access_token"]
    else:
        print("Token acquisition failed", result)  # Examine result["error_description"] etc. to diagnose error
        return None


token = acquire_and_use_token()


http_headers = {'Authorization': 'Bearer ' + token,
                'Accept': 'application/json',
                'Content-Type': 'application/json'}

graph_url = 'https://graph.microsoft.com/v1.0/sites/' + siteId + '?$select=id,webUrl,displayName'

siteResponse = requests.get(graph_url, headers=http_headers)
print(siteResponse.status_code)
site = json.loads(siteResponse.content)
# print("Site (raw) : ")
# print(site)
print("Site webUrl : ", site["webUrl"])
print("Site displayName : ", site["displayName"])

# Lists
graph_url = 'https://graph.microsoft.com/v1.0/sites/' + siteId + '/lists'
listsResponse = requests.get(graph_url, headers=http_headers)
print(listsResponse.status_code)
lists = json.loads(listsResponse.content)
# print("Site lists (raw):")
# print(lists)
print("Site lists:")
for list in lists["value"]:
    print("  Display Name:", list["displayName"])
    print("   Id:", list["id"])
    print("   Web Url:", list["webUrl"])
    print("   Created Date:", list["createdDateTime"])
    print("   Last Modified Date:", list["lastModifiedDateTime"])

Application permissions

If your scenario is to call Graph API from Python with application permissions (aka unattended or daemon app) – the main difference is authentication. It is described here. It also requires App registration configured like this.

Azure ACS retirement: Track down ACS apps

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Since Microsoft announced retirement of legacy Azure ACS – all SharePoint admins are working against the clock. ACS permissions were here for 10+ years and there are tons of videos and blogs guiding users how to get these permissions and use it in apps. And imagine how many ACS apps are still there accessing SharePoint sites. We do not want business screams “My critical process stopped working! Do something right now!”. So we would get the list of such apps that are still using ACS to access SharePoint, get apps owners, sites and sites owners. The ultimate goal is to communicate to right people and let them know that ACS is deprecated now and engage them to update their solutions to use only modern authentication.

What kind of apps we are talking about, specifically? I can see the following options:

  1. Apps that were registered in SharePoint via AppRegNew.aspx (aka SharePoint app-only service principals) and provided with permissions in SharePoint via AppInv.aspx
  2. Apps that were registered in Azure (Entra Id) and provided with permissions in SharePoint via AppInv.aspx

Techniques we can use to get data:

  • analyze audit log to get events where apps are accessing sites
  • analyze audit log to get events where ACS permissions were provided to sites
  • get data from system that tracks request for new ACS permissions
  • use reports from admin center
  • use the PnP Microsoft 365 Assessment Tool 
  • get report on apps owners and permissions from from Entra Id

Let us deep dive into each data source to see if it is actually helps us to get ACS apps in use…

Audit log: apps accessing sites

Microsoft 365 audit log is supposed to save all events happening in Microsoft 365. It is available for admins via GUI, PowerShell Exchange Module and Graph API. GUI Search m365 audit log now lives under Microsoft Purview – Solutions – Audit.

GUI search Audit Log under Purview

Unfortunately, when an App registered in Azure and provided with ACS access (via appinv) is accessing SharePoint sites – no events are saved in m365 audit log.

SharePoint app-only principals (apps registered in SharePoint via appregnew) are tracked in m365 audit log. Events would have a UserId “app@sharepoint” (yes, single user id for all apps). Other event details would include activity/operation (PageViewed, FileModified etc.), Item (full Url of a document or page etc.), AppAccessContext (includes ClientAppid, ClientAppName), ApplicationId (yes, this is how we know what app access what url on the site), and many other details

Get Audit Log via Microsoft Graph API

The following reports are available in preview only (under beta):

Service principal sign-in activity

This report is available through the servicePrincipalSignInActivity resource type and details the sign-in activity for a service principal in your tenant. The sign-in activity can be delegated or application-only scenarios. For application-only scenarios, the application credential activity provides additional information on the credential usage.

Service principal sign-in activity report provides the following details for every service principal:

  • id,
  • appId,
  • lastSignInActivity,
  • delegatedClientSignInActivity,
  • delegatedResourceSignInActivity,
  • applicationAuthenticationClientSignInActivity,
  • applicationAuthenticationResourceSignInActivity

More on Service principal sign-in activity

Application credential sign-in activity

This report is available through the appCredentialSignInActivity resource type and details the usage of an app credential (secret, certificate, or federated identity credential) in your tenant.

Application credential sign-in activity report provides the following details for every service principal credential:

  • id, keyId, keyType, keyUsage,
  • appId, appObjectId, servicePrincipalObjectId,
  • resourceId,
  • credentialOrigin,
  • createdDateTime,
  • expirationDateTime,
  • signInActivity

More on Application credential sign-in activity

Application sign-in

Evaluate the usage of application sign-ins in your tenant using either a summary report or a report that provides details of sign-ins, such as the number of sign-ins and whether any errors occurred during sign-in.

Application sign-in report provides the following details for every service principal:
aggregatedEventDateTime, appDisplayName, appId, id, signInCount, status

More on Application sign-in

Audit log ACS permissions provided events

This is relatively easy. There are just 3 kinds of events that might help us to understand ACS usage in tenant:

SharePointAppPermissionOperation

Pull audit logs with record type is SharePointAppPermissionOperation so you’d get events where permissions were provided to apps. Operation type (activity) would be like AppPermissionGrant.

Microsoft started logging this record type not long ago and there is no documentation found (as of Feb 2025). So the only I noticed that might help is:

  • if user id is “app@sharepoint” – that indicates Sites.Selected permissions were provided to the app
    (e.g. via Grant-PnPAzureADAppSitePermission )
    under “AppId” you’d have an app (client) id of the client app (permissions provided to) in the form of
    “i:0i.t|ms.sp.ext|<appId>@<tenantId>”
    under “ApplicationId” and “AppAccessContext – ClientAppId” – you’d have an app (client) id of the admin app (permissions provided via)
    ApplicationDisplayName would contain the display name of the admin app
    Other fields: RecordType 205, UserType 5, AuthenticationType OAuth
  • if user id is one of your actual user’s account in tenant – that indicates ACS permissions were provided to the app (e.g. via appinv.aspx page at SharePoint site)
    under “AppId” you’d have an app (client) id of the client app (permissions provided to) in the form of
    “i:0i.t|ms.sp.ext|<appId>@<tenantId>”
    there would be no “ApplicationId” field and under “AppAccessContext” no ClientAppId
    ApplicationDisplayName Unknown
    Other fields: RecordType 205, UserType 0, AuthenticationType FormsCookieAuth

Appregnew.aspx and appinv.aspx

You can pull audit logs with record type is SharePoint and activity type (operation) is PageViewed and keyword for free search is appregnew. You’d get events when there was an attempt to register a new SharePoint app-only service principal.

The same but with appinv as a search keyword – to get events when there was an attempt to provide ACS permissions for a SharePoint app-only service principal or for an Azure App registration.

In both cases we know that there was an intention to have a principal with an ACS access. We can reach these people to inform that ACS is deprecated and so and so. Worst scenario – we notify somebody who already know that.

Some time ago (around mid – 2023) Microsoft by default disabled ability for site owners registering apps and providing permissions in SharePoint via Appregnew.aspx and appinv.aspx. So since then only SharePoint service admins could provide ACS permissions to apps. In this case you’d check with your request tracking system – to whom ACS were provided.

System that tracks request for new ACS permissions

In case you have a process of providing ACS permissions… Process might include tickets to service desk or similar kind of system… Anyway – check if you can get data from that system – like who requested for what app to what site etc…

Reports available at admin center

So far the only report that might help is in development (see Microsoft 365 Roadmap – feature Id 417481) and scheduled to be available in March 2025.

“Enterprise Application Insights is a powerful report which helps SharePoint Administrators to discover all the SharePoint sites that are allowed access by third-party applications registered in your tenant. The report also provides details on the application’s permission and requests count to help admins take further action to strengthen the security of the site. It is part of SharePoint Advanced Management capabilities.”

The feature is already documented here: Generate App insights reports and is seems like the report will not be available for all tenants – but just for tenants with Microsoft SharePoint Premium (SharePoint Advanced Management) or Copilot license assigned.

PnP Microsoft 365 Assessment Tool 

Microsoft 365 Assessment Tool is an utility designed by PnP team a while ago and since then serves SharePoint admins very well. In particular, it helps helps us identify and evaluate the Azure ACS usage for tenant by providing the usage data of ACS principals, and even generating a Power BI reports.

If you run this tool specifying AddInsACS mode, it provides you with:

  • classicacsprincipals report that includes apps with Allow AppOnly permissions.
    Details are: App Ids, if the app has Tenant or Site Collection Scoped Permissions, RedirectUri, AppDomains and ValidUntil
    If the ValidUntil field contains specific date – that means the app was registered via appregnew
    If the ValidUntil field contains “01/01/0001 00:00:00” date – that means the app was registered in EntraId
  • classicacsprincipalsites – sites these apps have access to
    Details are: AppIdentifier, ServerRelativeUrl
  • classicacsprincipalsitescopedpermissions – list of apps permissions to sites
    Details: AppIdentifier, ServerRelativeUrl, SiteId, WebId, ListId, Right (Read/Write/FullControl/Guest etc.)
    If the WebId field equals zeros, that means rights were provided to entire site collection
  • some other details

Unfortunately, this tool does not provide when the app was last time authenticated or when the app accessed the site

I use the following PowerShell to start the tool, get status and export reports:

$tenantDomain = "" # "contoso.sharepoint.com"
$clientid = "" # 
$certThumbprint = ""
$certPath = "My|CurrentUser|" + $certThumbprint

./microsoft365-assessment.exe start --mode AddInsACS --authmode application --tenant $tenantDomain --applicationid $clientid --certpath $certPath

./microsoft365-assessment.exe status

./microsoft365-assessment.exe report --id <report id> --mode CsvOnly --path ".\ACS-reports"

Highly recommended: SharePoint Add-In and Azure ACS Assessment

Report on apps owners and permissions from from Entra Id

Using all the methods above – you’d get a list of active service principals that use legacy ACS authentication. But to whom we need communicate to regarding this service principals? Obviously, we need this service principals owners. There are multiple options how to get an app owner from Azure (Entra Id):

More Observations

Test scenario 1
DisableCustomAppAuthentication is true, i.e. ACS are not allowed in tenant.
SiteOwnerManageLegacyServicePrincipalEnabled -s false, i.e. site owners cannot register apps at sites or provide permissions to app on sites.
It is not possible for admin to go to appregnew.aspx and create an app (app-only spn).
I registered apps in Azure.
It is possible for admin to go to appinv.aspx and “provide” permissions to the azure app registrations.
An app is shown under appprincipals.aspx only in case if ACS access was provided to app but Sites.Selected access was not provided. The moment you provide Sites.Selected access for the app to the site – the app disappears from list of apps under appprincipals.aspx page. It does not help if you remove Sites.Selected permissions.
Connect-PnPOnline works with certificates or with secrets.
Get-PnPSite works only if connection was made with a Certificate (if connection was made with secret – it gives 401 unauthorized).

Test scenario 2
DisableCustomAppAuthentication is false, i.e. ACS are allowed in tenant.
SiteOwnerManageLegacyServicePrincipalEnabled -s false, i.e. site owners cannot register apps at sites or provide permissions to app on sites.
Connect-PnPOnline and Get-PnPSite works with certificates or secrets if ACS access was provided for an app to at least one site.
If there was no ACS permissions provided for the app – Get-PnPSite gives “Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))”

Error messages and possible fixes

“Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))” – happens if you try to access SharePoint API with an Entra Id app registration that have an API permissions but do not have legacy ACS permissions being authenticated with a secret.
Solution option 1: try authentication with a certificate.
Solution option 2: use Microsoft Graph API.

“The remote server returned an error: (401) Unauthorized.” – happens if you try to access SharePoint API being authenticated with a certificate with an app registration that do not have modern API permissions correctly provided.
Solution: ensure app registration is configured with SharePoint API permissions.

“(403) Forbidden” – happens if you try to access SharePoint API being authenticated with a secret with an app registration that do not have modern API permissions correctly provided.
Solution: ensure app registration is configured with Graph API permissions.

“AccessDenied”,”Either scp or roles claim need to be present in the token.” – happens if you try to access Graph API being authenticated with a secret with an app registration that do not have modern API permissions correctly provided.
Solution: ensure app registration is configured with Graph API permissions.



References

SelectedOperations.Selected permissions in SharePoint

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Microsoft says “Initially, Sites.Selected existed to restrict an application’s access to a single site collection. Now, lists, list items, folders, and files are also supported, and all Selected scopes now support delegated and application modes.”. This article deep-dives into providing and using SelectedOperations.Selected granular permissions to SharePoint:

Lists.SelectedOperations.SelectedProvides application access to a specific list
ListItems.SelectedOperations.SelectedProvides application access to one or more list items, files, or folders
Files.SelectedOperations.SelectedProvides application access to to one or more files or library folders

Set of SelectedOperations permissions is exactly what Microsoft promised a few years ago. And this is great, as we really need granular access to SharePoint sites. I’ve been supporting enterprise SharePoint for more than 10 years now, and I know that it was always a concern when application require access to a list/library or a folder or even document, but admins have to provide access to entire site.

Especially, I believe, this feature becomes more in demand because of Copilot for Microsoft 365. As for now – it’s mostly developers and data analytics who needs unattended application access to SharePoint, but what if regular users powered with m365 Copilot license start creating autonomous agents?

So below is my lab setup, PowerShell scripts and guides with screenshots on how to provide granular (not to entire site but to library/list or folder, or even just one document or list item) permissions to SharePoint and how to use provided permissions.

Admin App

First, we need an Admin App – an app we will use to provide permissions.

The only requirement – this app should have Microsoft.Graph Sites.FullControl.All API permissions consented:

Target Site and Dev Setup

For this lab/demo setup, I have created a team under Microsoft Teams (so it’s a group-based Teams-connected SharePoint site), then test list and test library:

There must be an App Registration for client application – application that will have access to Test-List-01 and Test-Lib-01 only. This app registration should have Microsoft Graph “Lists.SelectedOperations.Selected” API permissions consented:

and I will use Python to access SharePoint programmatically.

At this moment (we have a client app and secret, and “” API permissions, but did not provide for this app access to specific sites or libraries) – we should be able to authenticate to Microsoft 365, but not able to get any kind of data (we can get token, but other call to Graph API would return 403 error – Error: b'{“error”:{“code”:”accessDenied”,”message”:”Request Doesn\’t have the required Permission scopes to access a site.”,):

PowerShell script to provide selectedoperations.selected access for an app to a specific list would be as below. Here we use plain calls to MS Graph API. Full script for your refence is available at GitHub, but here is the essential part:

$apiUrl = "https://graph.microsoft.com/beta/sites/$targetSiteId/lists/$targetSiteListId/permissions"
$apiUrl 
$params = @{
	roles = @(
	    "read"
    )
    grantedTo = @{
        application = @{
            id = $clientAppClientId
        }
    }
}
$body = $params | ConvertTo-Json
$response = Invoke-RestMethod -Headers $Headers -Uri $apiUrl -Method Post -Body $body -ContentType "application/json"

Client Application

I use Python console app as a client application. Link to the code at the GitHub is shared below under References, but the core part of the Python code is (I do not use any Microsoft or other libraries here, just plain requests to Microsoft Graph for authentication and for data):

import requests
import json
from secrets import clientSc, clientId, tenantId, siteId, listId 

# specify client id, client secret and tenant id
# clientId = ""
# clientSc = "" 
# tenantId = "" 

apiUri = "https://login.microsoftonline.com/" + tenantId + "/oauth2/v2.0/token"

body = {
    "client_id"     : clientId,
    "client_secret" : clientSc,
    "scope"         : "https://graph.microsoft.com/.default",
    "grant_type"    : "client_credentials" 
}

try: 
    response = requests.post(apiUri, data=body)
    token = json.loads(response.content)["access_token"]
except:
    print("Error: ", json.loads(response.content)["error_description"])
    exit()

print("Got token: ", token[0:10], "...")
headers={'Authorization': 'Bearer {0}'.format(token)}

# Get specific site list
print("Geting specific site list")
# graph_url = 'https://graph.microsoft.com/v1.0/sites/' + siteId + '/lists/' + listId
graph_url = 'https://graph.microsoft.com/beta/sites/' + siteId + '/lists/' + listId
graphResponse = requests.get(   graph_url, headers=headers )
print(" Response status code: ", graphResponse.status_code)
if graphResponse.status_code == 200:
    list = json.loads(graphResponse.content)
    print(" List display name: ", list["displayName"])

Note.
I’m not sure if it’s a bug or my incorrect setup, but I noticed that if I provide access for the app to the list – app can read site.

TBC…

References

Securing Storage Account in Azure Function

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A storage account that is created as part of an Azure Function App out of the box has some configuration tradeoffs that can be considered vulnerabilities. Let’s look at what can be changed to improve the security of the storage account without affecting the functionality of the Azure Function App.

Public (anonymous) Access

Storage account blob anonymous (public ) access should be disallowed. Though having this Enabled does not allow anonymous access to blobs automatically, it is recommended to disable public access unless the scenario requires it. Storage account that support Azure Function App is not supposed to be shared anonymously.

Navigate to your Storage Account at Azure portal, Settings/Configuration, then
for “Allow Blob anonymous access” select “Disabled”:

MS: “When allow blob anonymous access is enabled, one is permitted to configure container ACLs to allow anonymous access to blobs within the storage account. When disabled, no anonymous access to blobs within the storage account is permitted, regardless of underlying ACL configurations. Learn more about allowing blob anonymous access“.

Storage account key access

This is also considered as vulnerability and it is recommended to disable Storage account key access.

NB: (Jan 2025) It is not possible to Set “Allow storage account key access” to Disabled if you are using Consumption or Elastic Premium plans on both Windows and Linux without breaking the function app. For other plans – it’s possible but requires some work.

Set “Allow storage account key access” to Disabled:

MS: “When Allow storage account key access is disabled, any requests to the account that are authorized with Shared Key, including shared access signatures (SAS), will be denied. Client applications that currently access the storage account using Shared Key will no longer work. Learn more about Allow storage account key access“

The problem is it seems like the function app ootb is configured to use key access, so just disabling storage account key access breaks the function app.

For the function app to adopt this new setting, you’d need:

  • provide access for the function app to the storage account
  • reconfigure the function app for authorization via Microsoft Entra credentials

Here is the separate article “Function app to access Storage via Microsoft Entra credentials” with the detailed research and step-by-step guide, so here I just summirise it:

Function App Hosting PlanAllow Storage Account Key Access
Flex ConsumptionPossible to disable Storage Account Key Access
Consumption, PremiumNot Possible to disable Storage Account Key Access
DedicatedPossible to disable Storage Account Key Access
Containertbc

References

Azure Key Vault Purge Protection

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Azure key vault is something where you can store keys, secrets, certificates that you’d need to access services (e.g. call Graph API).

What if somebody malicious get access to key vault (that is not what we want but we should consider this as possible risk)? Surely leaked secrets is a serious issue (separate topic), but imagine if that somebody also deletes key vault content – if so, we will simply lose this data, which will break the functionality of the solution and our existing systems will stop working.

So enabling purge protection on key vaults is a critical security measure to prevent permanent data loss. This feature enforces a mandatory retention period for soft-deleted key vault contents (e.g. secrets), making them immune to purging during the retention period.

In a nutshell, you’d just select “Enable purge protection” under the key vault Settings/Properties (notice, that once enabled, this option cannot be disabled):

For details, please refer to the following articles:

References

Automating SharePoint operations with Azure Functions

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There are many scenarios for SharePoint or Teams automations, and in most cases you need to run some code on scheduled basis (e.g. every 5 minutes or every 24 hours etc.). This is where timer-triggered Azure Functions might help. In this article I will provide use cases, overview of the whole scenario and technical setup, and provide links to the detailed step-by-step guides for configuring different parts of the entire solution.

Possible scenarios

Possible scenarios (end-user-oriented):

  • Create site upon user request
  • Convert site to a HUB site upon user request
  • Set site search scope upon user request
  • Setup site metadata (site custom properties)
  • Request usage reports/analytics

Possible scenarios (admin-oriented):

  • Provide temporary access to the site (e.g. during troubleshooting)
  • Provide Sites.Selected permissions for the App to the Site
  • Disable custom scripts or ensure custom scripts are disabled
  • Enable custom scripts (e.g. during site migration)
  • Monitor licenses – available, running out etc.

Typical setup

Front-end

SharePoint site works as a front-end. You do not need to develop a separate web application, as It’s already there, with reach functionality, secured and free.

The site can have:
– one or more lists to accept intake requests
– Power Apps to customize forms
– Power Automate to implement (e.g. approval) workflows, send notifications etc.
– site pages as a solution documentation
– libraries to store documents provided as response to requests

You can provide org-wide access to the site if your intention is to allow all users to submit requests or secure the site if you want to accept requests only from a specific limited group of people.

Back-end

Timer-triggered Azure Function works as a back-end. The function can be scheduled to run based on job specific requirements (e.g. every 5 or 10 minutes, or daily or weekly etc.). The function can be written in PowerShell, C#, Python etc.

The function’s logic is to

  • read SharePoint list, iterate through items to get intake requests
  • validate request eligibility
  • perform action
  • share results (e.g. update intake form, send e-mail, save document to library etc.)

Configuration

There should not be an issue to setup a front-end. You’d just need a solid SharePoint and Power Platform skills.

For the back-end the solution stack would include the following tools/skills:
– Azure subscription to host solution
– Registered Apps to configure credentials and API access permissions
– Azure Function App to actually run the code
– Azure Key Vault to securely save credentials
– programming skills in language/platform of choice
– SharePoint API, Microsoft Graph API

Please refer to the separate article Configuring Azure Function App and Key Vault to work with Microsoft 365 SharePoint via Graph API for the basic setup.

Secure

Having basic setup in place, we’d improve solution security. Specifically, we’d address the following:

  • Azure Function network security
  • Key Vault network security
  • Storage Account network security
  • Key Vault purge protection
  • tbc…

TBC…

References

Azure Function app to access Storage via Microsoft Entra credentials

1 Reply

There is a known problem with Azure Function App security configuration. Ootb function app access to storage is configured using shared keys. This is considered as potential vulnerability. Disabling storage account key access breaks the app. This article tells how to reconfigure the app to use Microsoft Entra credentials vs shared keys.

When the function app is created – a Storage Account is created to support function app. By default, storage account has shared keys enabled and function app is configured for shared keys. So we’d need:

  1. Enable function app managed identity
  2. Provide access for the function app managed identity to the storage account
  3. Configure function app to use managed identity

Enabling function app managed identity

It’s done via Azure portal -> function app -> Settings -> Identity:

Providing access for the function app’s managed identity to the storage account

First, you’d navigate to the Azure portal -> Storage Account -> Access Control (IAM)
and Add new role assignment.

then you’d select “Storage Blob Data Owner” role, “Managed identity” your app identity

Configure function app to use managed identity

Responsible app settings are (you can find them under your app Settings -> Environment Variables -> “App settings”:

You can remove “AzureWebJobsStorage” and replace it with “AzureWebJobsStorage__accountName” as per here.

For the WEBSITE_CONTENTAZUREFILECONNECTIONSTRING, unfortunately, it says that this env variable is required for Consumption and Elastic Premium plan apps running on both Windows and Linux… Changing or removing this setting can cause your function app to not start… Azure Files doesn’t support using managed identity when accessing the file share…

Possible error messages

If you have a Function app with Consumption or Elastic Premium plans and completed steps above to disable function storage account key access – your function app will not work. There will be no new invocations. Personally, I was able to observe the following error messages:

“We were not able to load some functions in the list due to errors. Refresh the page to try again. See details” :

We were not able to load some functions in the list due to errors. Refresh the page to try again. See details


Function App with Dedicated Plan

If you have a function app created based on dedicated plan (App Service):

then under function “Environment variables” you’ll see:

e.g. there is a AzureWebJobsStorage (that can be updated) and no WEBSITE_CONTENTAZUREFILECONNECTIONSTRING (than is required).

So, for the function app created with dedicated plan (App Service) – if you followed steps above (provide a role to managed identity, created AzureWebJobsStorage__accountName, removed AzureWebJobsStorage and disabled key access – the function should work.

Function App with Flex Consumption plan

Flex Consumption plan is a new linux-based plan (GA announced Nov 2024), and it looks promising – it’s still consumption, but supports virtual networks and allows fast start (and some more nice features).

What I do not like is it does not support installing dependencies via requirements.ps1 – you have to go with custom modules here (it says: Failure Exception: Failed to install function app dependencies. Error: ‘Managed Dependencies is not supported in Linux Consumption on Legion. Please remove all module references from requirements.psd1 and include the function app dependencies with the function app content).

For our specific needs – disabling storage key access and using function identity to access it’s own storage – I found the following promising: “By default, deployments use the same storage account (AzureWebJobsStorage) and connection string value used by the Functions runtime to maintain your app. The connection string is stored in the DEPLOYMENT_STORAGE_CONNECTION_STRING application setting. However, you can instead designate a blob container in a separate storage account as the deployment source for your code. You can also change the authentication method used to access the container.”

Let us create a function with a hosting option “Flex Consumption plan” (all the other settings are by default) via Azure Portal:

and right away we can see that app is using storage keys by default via environment variables: AzureWebJobsStorage (we know how to deal with) and DEPLOYMENT_STORAGE_CONNECTION_STRING (no description found).

Let us try to create a function app different way (customized as per this). First, we’d create a storage account. When creating a function app – we’d select an existing storage. I did not find any options to select function managed identity and configure the function to use managed identity to access storage account during function app creation wizard.

Let us try to reconfigure the existing app

After this – a system identity was created and the role “Storage Blob Data Contributor” was assigned to this identity to the storage account. Environment variables did not go. Let us disable access keys under storage account – and… and function app stopped working.

Since environment variables are still here – let us blame “AzureWebJobsStorage” and let us do the trick with it – create a new “AzureWebJobsStorage__accountName”, put our storage account name as a value, remove “AzureWebJobsStorage” and restart the app… Drumroll, please! And hooray! The function has started working again!

“Container app environment” – to be tested

tbc…

References