Hackers blackmail Greek banks demanding bitcoin ransom

© Kacper Pempel
At least three Greek banks have been hit by cyber-attacks from a group of hackers demanding a bitcoin ransom. The group called Armada Collective threatened to disrupt the banks’ electronic transactions unless each paid a 20,000 bitcoin ($7 million) ransom.

The Armada Collective attacked the systems of three Greek banks (including the central bank) which interrupted transactions for a few minutes followed by the ransom demand.

"No bank responded to this extortion, so the same hackers tried again at the weekend and today," a police official was cited as saying on Monday by the Financial Times. "But we had strengthened our defense in the meantime, so no disruptions took place."

He added that cyber-experts from the Greek central bank and the police electronic crime unit were monitoring the banks' computer systems.

In June, the Greek government introduced capital controls to back up the country’s financial system and avoid the possibility of a Greece leaving the euro. Since then Greece has seen a rapid growth in internet banking. More than 200,000 new internet bank accounts have been registered allowing customers to make domestic transactions.

A senior Greek banker told the FT that the latest attacks were extremely serious but the country managed to “boost security and add capacity with the help of local internet service providers.”

Criminal cyber- attacks on global financial institutions have been on the rise. Hacker groups often demand huge bitcoin ransoms to prevent future attacks.

While bitcoin and other digital currencies have been initially regarded as "intangible assets," that attitude has recently changed. Some countries and financial institutions suggested treating bitcoin on par with standard money.

READ MORE: Australia pushes to recognize bitcoin as regular currency

Bitcoin detractors claim that bitcoin is a volatile and vulnerable currency, as well as a tool for money laundering and tax evasion. Bitcoin supporters point out that any currency can be used in illegal activities.