Hackers infiltrated over 100 banks in several countries, stealing millions of dollars in possibly the largest bank theft the world has seen, according to a report published by the New York Times on Saturday.

The Times said it received an advance copy of an upcoming report by Moscow-based Kaspersky Lab that details how banks in Russia, Japan, the United States, and other countries fell victim to malware starting in late 2013 that allowed the hackers to watch video feeds, view daily operations, and impersonate bank officials.

The malware apparently allowed the hackers to transfer money from the banks to fake accounts. According to the Times, Kaspersky Lab said the total theft could be more than $300 million, although the cybersecurity firm has not nailed down an exact figure. Each transaction was limited to $10 million and some banks were hit more than once, according to the publication.

“This is likely the most sophisticated attack the world has seen to date in terms of the tactics and methods that cybercriminals have used to remain covert,” Chris Doggett, of Kaspersky's Boston office, told the Times.

Kaspersky Lab does not name the banks involved in the massive theft operation in its report, and no banks have revealed that they have been hacked, according to the Times.

The publication also noted that the White House and FBI have been notified of the report.

Kaspersky Lab did not immediately respond to Ars’ request for comment. We'll update this story as more information about the report becomes available.