The following are links to Cybersecurity related News and Threat Intelligence regarding APT’s and other threat actors.

http://www.newsnow.co.uk/h/Technology/Security (Excellent news aggregation site)
https://docs.google.com/spreadsheets/d/1H9_xaxQHpWaa4O_Son4Gx0YOIzlcBWMsdvePFX68EKU/edit#gid=1864660085 (Excellent Google Doc that lists APT Groups, operations, tools, and objectives)
https://github.com/CyberMonitor/APT_CyberCriminal_Campagin_Collections
https://darknetdiaries.com
https://www.symantec.com/content/dam/symantec/docs/security-center/white-papers/istr-living-off-the-land-and-fileless-attack-techniques-en.pdf
https://en.wikipedia.org/wiki/Advanced_persistent_threat (The APT Attack Cycle diagram is here)
https://attack.mitre.org/ (The MITRE ATT&CK™ framework is excellent) 
https://attack.mitre.org/software/
https://attack.mitre.org/wiki/Groups
https://attackevals.mitre.org/
https://infosec-conferences.com/ (Cybersecurity Conferences listed here)
\https://thehackernews.com/
https://www.theregister.co.uk/security/
The Security Podcast Network
https://krebsonsecurity.com/ https://www.peerlyst.com/ https://www.schneier.com/ https://www.thecipherbrief.com/ https://www.social-engineer.org/blog/ https://taosecurity.blogspot.com/ https://www.troyhunt.com/ https://blog.talosintelligence.com/ https://www.fireeye.com/blog.html https://googleprojectzero.blogspot.com/ https://nakedsecurity.sophos.com/ https://www.sans.org/security-awareness-training/blog
Threatpost | The first stop for security news
https://www.reddit.com/r/netsec/ https://www.wired.com/category/threatlevel/ http://www.zdnet.com/blog/security/ https://arstechnica.com/ https://www.darkreading.com/ https://techcrunch.com/ https://securityaffairs.co/wordpress/
https://www.wired.com/ https://www.ethicalhacker.net/