Brex briefly looked at Abnormal but decided not to implement it, Hillick said.
"I don't believe in black box as a philosophy," he said. "It reduces visibility, so I can't see how Brex is going to be attacked. I can't see what tactics or techniques are being used. With Sublime, I can do that."
Abnormal's software is fully autonomous, its co-founder and CEO, Evan Reiser, said in a statement.
But Reiser said "it is still highly transparent when it comes to explaining the techniques attackers are using."