MFA and Invalid Connection in Flow

[Bjarke]

Hi,

I have a tenant in which MFA has been activated for all users. I have created a user to run all my flows, but the flows breaks after a while and the only message i see is "Invalid connection". I assume this is because of MFA. Are there anyway to handle this or do i have to disable MFA for that specific user ?

[v-yamao-msft]

Hi @Bjarke,

I’m afraid that it might be caused by MFA authentication.

Please suggest your user try to refresh their connections to see if it will work.

There is a similar issue on this thread, Staff @TravisB has some suggestion on it. Please check it for more details:
https://powerusers.microsoft.com/t5/General-Flow-Discussion/Flow-Connections-error-due-to-Credential...

Best regards,
Mabel Mao

[PeterSelchDahl · Accepted solution]

This solution should work for customers that use Microsoft Flow and service accounts for running the flow: https://blog.peterdahl.net/2018/01/09/microsoft-flow-and-azure-conditional-access-azure-mfa/

I still need feedback from Microsoft around a solution that will work for end-users.

/Peter Selch Dahl

[dbogda]

Peter's answer was the fix we needed to bypass Azure Conditional Access(MFA) in order to keep Flows running. In case anyone needs the Flow IPs formatted for MFA exceptions, here is the US list formatted and sorted. This is for the Logic App Service IP List from Peter's Flow Limits and Configuration link.

13.91.252.184/32

13.92.98.111/32

40.114.82.191/32

40.117.99.79/32

40.117.100.228/32

40.118.241.243/32

40.118.244.241/32

40.121.91.41/32

52.160.90.237/32

52.160.92.112/32

137.135.106.54/32

138.91.188.137/32

- Dan

https://www.disruption.consulting

[PeterSelchDahl]

Great to hear that it resolved your issue. I know that Microsoft is aware of the issue and that this solution is not the best in the world. I gets the job done for now 🙂

[helsby]

Only works if you have Azure AD premium though, otherwise you can't add a policy.

Another solution would be to support app passwords?

[Lucas-Rojo]

Hi all,

Is this issue still current? If so, do we know if Microsoft is planning to solve this issue?

Thanks in advance for any insights.

KR,

Lucas

[gtsmith]

Hi Peter - thanks for this post. Are you aware of any negative security consequences that could arise from bypassing MFA in this fashion?

[Anonymous]

I'd take a guess that generally speaking it's never good practice to "bypass" security. So this is not a great workaround. Understandable if absolutely required to continue using Flows that are running key business processes/applications etc.

[helsby]

Hi Lucas - I would say the problem is still current unless you pay up for the expanded Azure rights so allow conditional access.

I reduced the issue on my end by increasing the reprompt issue from 2 days to the maximum allowed. Not an ideal sitation by any means.

[PeterSelchDahl]

Yes. This is in no way best practice from a security point of view. The workaround would allow potential hackers to execute code or task using Microsoft Flow without requiring to prove their identity using two factor authentication. I would also recommend using this solution as a last resort. I hope that Microsoft will find a solution for this issue. Many other Microsoft services are also strungling with delegated credentials / doing stuff on behalf of users as most of these require passive authentication flows. 

/Peter

[TomDegler]

Thank you!

It helped me to solve my problem!

Addresses for EU:

13.69.227.208/28
13.69.64.208/28
52.174.88.118/32
52.178.150.68/32
137.117.161.181/32

[PaulMathasaran]

Hi,

Just a quick follow up, is this issue resolved with Microsoft?

What is the solution?

[StevieLamb]

Hi Peter,

Isn't it possible to run a Flow using the OAuth2 "client credentials flow" by providing a tenant id, client ID and secret (or certificate, this option maybe not so useful in Power Automate)?

I'm less experienced with Automate so uncertain of the limitations here.

Thanks,

Stevie

[StevieLamb]

Your observations on the security risks are spot on IMHO, and I'm a penetration tester so I look for opportunities like this.

Aside from my suggestion of using OAuth2 "client credentials flow", another choice might be to combine the given workaround with a Conditional Access policy which enforces restrictions on where the Power Automate workload can be accessed from.

(I have not tested this, nor observed any limitations which might exist).