Hackers targeted Ukraine's largest mobile-only bank, Monobank, with a massive denial of service (DDoS) attack on Aug. 16, according to Oleh Horokhovskyi, the company's co-founder and CEO.
DDoS attacks direct excessive amounts of traffic at a website in order to overload its servers, often causing disruptions to service.
Monobank received around one billion service requests in three hours, Horokhovskyi reported via Telegram on Aug. 16.
"We are fighting it off while drinking coffee and donuts ... We are keeping the situation under control," he said.
Monobank has previously been targeted in similar cyberattacks. A DDoS attack in January sent over 580 million service requests to the bank's website.
Horokhovskyi did not identify a culprit, though previous threats have been linked to Russian hackers. Russia has launched thousands of cyberattacks against Ukrainian organizations since the start of its full-scale invasion.
Ukrainian hackers in turn have fought back against Russian cyberwarfare by launching attacks of their own. Ukraine's IT Army, a volunteer hacker group, claimed responsibility for a massive DDoS attack against Russian banks and Russia's Mir payment system in June.