Advice Request Port scanning alert in local network

[Frika]

Avira frequently reports a port scanner attack lately. Two computers are connected to our router. And the attacker's address is one of the two computers. So the "attack" is from inside. A comprehensive malware detection with various apps has brought no result. Is there an explanation why one computer scans the ports on the other? What can I do to find out which program is performing this port scanning action?
Thank you in advance

 

[Ink]

What do you use the 2 computers for? Browsing, media, gaming?

HTG Explains: What is Port Scanning?

A port scan is a bit like jiggling a bunch of doorknobs to see which doors are locked.

www.howtogeek.com

 

[Frika]

What do you use the 2 computers for? Browsing, media, gaming?

Yes, we use both of them for working, media, browsing - no gaming. This has been going on for about two weeks now. Is there any way to find out which application is doing this kind of port scanning? Or an advanced scanning option to find out if the attacker machine is infected?

 

[ForgottenSeer 103564]

Yes, we use both of them for working, media, browsing - no gaming. This has been going on for about two weeks now. Is there any way to find out which application is doing this kind of port scanning? Or an advanced scanning option to find out if the attacker machine is infected?

Going to assume this is a windows machine so will leave this link here. There are malware removal experts here that can assist you in checking your machine or advise you on the checking the network. One can not rely on the IP identified as port scanning as they can be spoofed on the same network even.

Windows Malware Removal Help & Support | MalwareTips

Windows malware removal help. Read pinned steps first; only authorized helpers may reply.

malwaretips.com

 

[Frika]

Going to assume this is a windows machine so will leave this link here. There are malware removal experts here that can assist you in checking your machine or advise you on the checking the network. One can not rely on the IP identified as port scanning as they can be spoofed on the same network even.

Windows Malware Removal Help & Support | MalwareTips

Windows malware removal help. Read pinned steps first; only authorized helpers may reply.

malwaretips.com

I forgot, yes both are Window 10 machines.