Ransomware-as-a-service (RaaS) crews have grown exponentially over the years. There are now a group of attackers whose very names are synonymous with RaaS and strike fear in the hearts of the organizations. The newer crews hardly have any noteworthy accomplishments to date and neither do they run a blog of their attacks. Tier I: The Powerhouses are responsible for a large number of attacks. Tier 2: The Challengers to the Throne are linked to quite a few confirmed attacks and have managed to name and shame the victims who refuse to pay a ransom. Tier 3: The New Kid on the Block is the new kid on the block.”]
Source: https://gbhackers.com/ransomware-operators-and-hackers/