Crypto.com CEO Kris Marszalek told Bloomberg on Wednesday that the attack earlier this week hit 400 users.
For what Marszalek said was a period of 13 to 14 hours, Crypto.com paused its users' ability to withdraw funds and subsequently asked its users to reset two-factor authentication.
The company informed its users they would need to sign back into their accounts and reset their two-factor authentication.
Marszalek said Crypto.com's 200 security professionals had created a "very robust" infrastructure and stated it had defence-in-depth.
"There are multiple layers, and in this particular incident, some of these layers were breached," he said.
"Which resulted in about 400 accounts having unauthorised transactions."
Marszalek added the impacted users had their funds fully reimbursed on the same day, and while he would not be drawn to put a figure on the amount of funds taken, he said the company was working on a postmortem that would appear on its blog in the next few days.
"In any case, one has to remember that given the scale of the business, these numbers are not particularly material."
While Marszalek did not put a number on it, PeckShield did, claiming around $15 million was being washed through a coin tumbler.
The CEO also said in other sections of the interview that he expected increasing use cases, such as blockchain gaming, to increase the number of cryptocurrency users to over one billion this year. He added the company was looking at potentially purchasing blockchain gaming companies.