Everyone seems too focused on source IP address which any solid IT person can tell you can be hijacked. Even the phone home IPs can be obfuscated but it seems awfully suspicious they all belong to net blocks going to NK if I'm understanding things.
It's a bit like saying "the attackers used malware which made DNS queries via the IP address 8.8.8.8, which has been used by NK in the past" - if anyone were really building a case on that key evidence, they should prepare to be laughed at.