For now, the threat actor is just claiming that they hacked BT. No prove whatsoever. Groups usually post a sample of the data when they claim a victim, but that is not the case, for now.
If you are asking if the main attack vector was phishing, they are not clear on that:
According to statements released by Brain Cipher, they have exploited critical weaknesses within Deloitte UK’s cybersecurity infrastructure.
Welcome! I dont know you background, but I would suggest get into selfhosting. There are several projects related to cybersecurity, fun and useful. Ex: MISP, Pihole, The Hive.
That's why I don't use Kaspersky :)
In my opinion, you will always be at the mercy of a government in this context: US, China, Russia. In the end it's a matter of choosing which one. FOSS maybe a little less, but in the end it's almost the same. That's my view, of course. That doesn't mean you can't give them a hard time ;)
This one does not spark joy.
Update: Israel Planted Explosives in Pagers Sold to Hezbollah, Officials Say (https://www.nytimes.com/2024/09/17/world/middleeast/israel-hezbollah-pagers-explosives.html)
Take that with a grain of salt.
Original research: https://www.jamf.com/blog/tcc-bypass-steals-data-from-icloud/