Please help me identify that flows

[diardnic]

I spent some times on fortianalyzer NOC view. Then i noticed some internal users have a lot of blocked udp outgoing connections. So far nothing looks suspicious on workstations. Whatsoever, i'd really like to understand what is going on.

So if you have any ideas.

ty

Sample

[andrewbailey · Accepted solution]

Hi diardnic, What are the clients may I ask? I traced a similar issue a year or two back to Windows 10 machines. There is a setting that allows windows 10 to pull updates via other Windows 10 machines (even outside your network). Originally the behaviour was to allow peering to any other Windows 10 machine and the results look a bit like what you are seeing. Lots of connections to random consumer IP addresses. I think The behaviour has now been changed and by default it now only uses machines on the local subnet. But it is still a setting that can be changed. Even by end users if not locked down. Let me know if that sounds plausible and I’ll try and find a screenshot or link for you. Kind Regards, Andy.

[Yurisk]

I'd suggest to track the connection(s) at the source - end PC, take for example TCPView from Sysinternals by Mark Russinovich (download from the Microsoft site) and it will show in real time process for each connection.

E.g:

[diardnic]

Yes Yuri, ty. But know that we have our hands on that laptop, no udp connection occurs, (at least not for now).

Shawn gave a good explanation. I believe he is right. I'm just trying to reproduce what i saw. 

[ShawnZA]

Asked our server guys to remove the the GPO policies from my PC, then switched the MS updates on to also download from pc's on the internet... plenty of UDP connections in the logs...

[diardnic]

Hi Shawn,

TY, this is very close to what i can see here in our logs.

While we dont have any TCP/7680 packets, and WUDO setting is enabled but on local netwok only.