About this question
In my SIEM tool, I got multiple alerts for communication with malware sites from Palo Alto firewall. I have seen many outbound communications from internal IPs toward IP: 74.217.31.51 having host name: match.basebanner.com which has many blacklisted domains to which internal hosts are communicating.
Reference:
https://www.virustotal.com/en/domain/match.basebanner.com/information/https://www.virustotal.com/en/ip-address/74.217.31.51/information/
Now I need to find out why these machines are communicating to these IPs. How to trace them and what proper remediation should I recommend to my client to handle them?