Anonymous has launched a 30-day attack against "all central banks" and major financial institutions, the activist-hacking group warned this week, after recent strikes on several major banks around the world by different hackers.
Anonymous claimed responsibility for a cyberattack on the National Bank of Greece on Tuesday, just a week after Qatar National Bank suffered a major data breach attributed by the media to a Turkish group called Bozkurt Hackers.
In March, the Bangladesh Central Bank reported $100 million stolen from its account at the Federal Bank of New York after a weekend break, according to media reports. The Bangladesh Central Bank said hackers had transferred the money to bank accounts in the Philippines and Sri Lanka.
An unnamed official from Greece's central bank told Reuters on Wednesday that the bank's website had suffered a denial-of service attack on Tuesday. This came after Anonymous announced the start of a "30-day campaign against central banks around the world," in a You Tube video.
30-day campaign
"Operation Icarus has moved into the next stage, for today, we have continually taken down the website of the Bank of Greece. This marks the start of a 30-day campaign against central banks around the world," the group, which adopts the so-called Guy Fawkes mask as its symbol for hacking, said on Tuesday.
In a later video, Anonymous extended its intended targets to include "MasterCard and Visa, Bank for International Settlements, all central banks, the IMF and the London Stock Exchange and every major banking system."
"Our message is clear. We will not let the banks win. We will be attacking the banks with one of the most massive attacks ever seen in the history of Anonymous," the group said.
Large-scale power disruption
In a different twist, hundreds of thousands of homes in Ukraine were left without electricity in December after an alleged malware attack on the power system. The attack was the first known example of hackers bringing down a major power network and attacks on major utility companies are an increasing concern for governments and corporates.
Plus, a U.S. cybersecurity expert claims to have discovered more than 272 million hacked email accounts, in what would be one of the biggest-ever data breaches. Alex Holden, who has previously uncovered other huge data breaches, said the accounts were offered to him for next to nothing by a Russian hacker. The news circulated in the media this week, after Holden announced it on the website of his company, Hold Security.
Some governments have launched expensive security programs in the wake of the threat. In February, President Barack Obama proposed a U.S. cybersecurity budget of $19 billion for the fiscal year 2017, a more than 35 percent increase from 2016.
In November, the U.K. government said it planned to almost double its investment in cybersecurity to £1.9 billion ($2.8 billion) over five years.
Meanwhile, the hackers who struck the Qatar National Bank have attacked a second bank and plan to leak more data, according toGulf News, which cited a cybersecurity expert.
"The attackers announced that they are going to make the data public for the second attack, in the next few days. This data could be used for ransom," Mohammad Amin Hasbini, a senior security researcher at Kaspersky Lab, said, according to Gulf News.
Follow CNBC International on Twitter and Facebook.