Traffic on udp/3478 (STUN) is been classified as 'unknown-udp' for MS-Teams app

[Andreikin]

Hello,

Most of our users are running Teams in a Office 365 on Windows laptops, from a network perspective it is just a connection on different ports to random hosts within 52.0.0.0/8 subnet. 

The problem we have is with udp/3478 port, some portion of it is STUN, some been identified as MS-TEAMS-AUDIO-VIDEO with latest app-ids. As mentioned in 'subject' of this very thread, about 5-10% of it daily was identified as 'unknown-udp'. Given that we have default policy to drop unknown traffic, we did a temporary workaround for this type of traffic and allowed it based on destination ports (service) and not application, thus loosing L7 inspection capabilities. Of course we want to fix signatures and that's why we are working with Palo to fix it for half of year already. Recently we had a progress here and new signatures rollout fixed significant volume of misidentified traffic, but some of those are still there. It happens on different platforms with different software version (9.1.x, 10.1.x), even Prisma Access-enabled GlobalProtect. 

Does anyone using Teams in enterprise also see same pattern? I can't believe that's only our issue given how wide Teams application is spread. Maybe someone with better insight into MS world know how to fix it or at least to properly reproduce so we can share captures with Palo? 

Right now it seems hard to predict where this issue might occur.

[reaper]

I've setup a whitelist for teams using the 'optimize required' subnets by microsoft: https://docs.microsoft.com/en-us/microsoft-365/enterprise/urls-and-ip-address-ranges?view=o365-world...

To those subnets i pretty much allow all applications (while still scanning everything)

[Andreikin]

@reaper Thanks. Does it mean you have 'ANY' in Application field for MSTEAMS rule? Given that Palo might fail to identify what application is used, can it properly scan 'unknown-udp' marked traffic? 

In our environment I believe security department won't agree with us to allow everything. 

Could you check in logs that you also have 'unknown-udp' for udp/3478 traffic?

Thanks.