The hackers, who have targeted the banks for a third time in five days, are demanding a ransom of 20,000 bitcoin (€7m) from each lender, The Financial Times reported.
According to media sources, the hackers threatened to crash the banks’ websites if they refused to pay the demanded ransom.
The hackers blocked the banks’ internet banking activity for few hours last week. However, they did not gain access to confidential client data or accounts, Reuters reported.
They initially staged attacks in the form of a distributed denial of service by sending several requests so that the strained websites collapse.
A special unit of Greece’s National Intelligence Service (EYP) has launched a probe to locate the hackers.
Reuters quoted a banker as saying: "We informed the police and the country’s secret services are involved.
"It’s an easy to handle situation. There is no need for bank clients to worry."
The banks’ computer systems are under the surveillance of cyber experts from the Greek central bank and the police electronic crime unit.
Image: The hackers blocked the banks’ internet banking activity for few hours last week. Photo: courtesy of Stuart Miles / FreeDigitalPhotos.net.
