According to Mr Krebs, a large successful Minecraft web server with more than 1,000 players logging on each day can earn up to $50,000 (£40,600) per month, mainly from players renting space to build their Minecraft worlds.
"The first clues to Anna Senpai's identity didn't become clear until I understood that Mirai was just the latest incarnation of an IoT [internet of things] botnet family that has been in development and relatively broad use for nearly three years," he writes.
The code for these earlier versions was often used to knock over web servers used to host Minecraft, he claims.
ProxyPipe - owned by Mr Coelho - had plenty of Minecraft servers as clients and in mid-2015 was hit by a massive attack, launched from a botnet made up of IoT devices such as web cameras.
Mr Coelho told the BBC that he had his suspicions about who was behind the attack: "Minecraft is a tight knit community. We know who is talking to who."
He alleged that the attack came from a competing security firm, which also offered DDoS protection to Minecraft clients.
He claimed that the founder of the security firm had previously run a Minecraft web server and was one of his clients.
He also claims that the Mirai author - Anna Senpai - contacted him via Skype at the end of September, partly to explain that the attack on his firm was "not personal" but also to brag that he had been paid by the owners of a large Minecraft server to launch an attack on a rival server.