CSOM C# with Multi Factor Authentication

Question

CSOM C# with Multi Factor Authentication

Amit Singh Rawat 731

Hi,
I have an application (webservice c#) to communicate with SP Online Tenant to fetch all site collections. All was working fine until client enable multi factor authentication.

How we can fetch all site collection from tenant having multi factor authentication enabled.

2 answers

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Answer 1

MichaelHan-MSFT 18,126

Hi @Amit Singh Rawat ,

Using class SharePointOnlineCredentials with userName and password to authenticate in SharePoint does not support for MFA enviroment.

As a workaround, you could install the package SharePointPnPCoreOnline: https://www.nuget.org/packages/SharePointPnPCoreOnline. And use the below way to get clientcontex.

   string siteUrl = "https://<tenant-name>.sharepoint.com/sites/test";    
   var authManager = new OfficeDevPnP.Core.AuthenticationManager();    
   // This method calls a pop up window with the login page and it also prompts    
   // for the multi factor authentication code.    
   ClientContext ctx = authManager.GetWebLoginClientContext(siteUrl);

Another workaround is using App Only autentication: https://www.c-sharpcorner.com/article/connect-to-sharepoint-online-site-with-app-only-authentication/

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Amit Singh Rawat 731 Reputation points

2021-05-25T04:34:37.797+00:00

Hi,
OfficeDevPnP.Core is not available. Not able to add its reference. I am using webservice (Not .NET API) with VS 2019.
Artillis Prado 0 Reputation points

2024-07-17T18:05:31.5766667+00:00
using (CC = authManager.GetWebLoginClientContext(siteUrl)) { List list = CC.Web.Lists.GetByTitle("TT_002_Test"); CamlQuery oQuery = CamlQuery.CreateAllItemsQuery(); ListItemCollection oCollection = list.GetItems(oQuery); CC.Load(oCollection); CC.ExecuteQuery(); }

System.Net.WebException: 'The remote server returned an error: (403) FORBIDDEN.'
I am using .NET 8, and I've already tried with GetACSAppOnlyContext but it wouldn't work because I need to access more than 5 SharePoint sites simultaneously. There was an error in CC.ExecuteQuery();

Answer 2

MichaelHan-MSFT 18,126

Hi @Amit Singh Rawat ,

Then you could create app password for the account, use the app password to authenticate. Read this article for more: https://learn.microsoft.com/en-us/azure/active-directory/user-help/multi-factor-authentication-end-user-app-passwords

Amit Singh Rawat 731 Reputation points

2021-05-25T09:56:37.09+00:00

IF MFA is enabled than there is a very high possibility APP Password feature is also disabled by client. As it just bypass MFA. Option provided in below link is good but not functional:

https://www.c-sharpcorner.com/article/connect-to-sharepoint-online-site-with-app-only-authentication
MichaelHan-MSFT 18,126 Reputation points

2021-05-26T03:06:08.567+00:00

@Amit Singh Rawat ,

If so, use SharePoint App-Only or Azure AD App-Only to grant access is your option. However, both of them need to add the SharePoint PnP Sites Core library nuget package:https://www.nuget.org/packages/SharePointPnPCoreOnline

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CSOM C# with Multi Factor Authentication

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