Three Greek banks have become the targets for a DDoS extortion campaign by a group of hackers who have threatened to disable their Websites unless they pay a $21 million ransom demand.
The hacking group, known as the Armada Collective, fired its first salvo at the banks last week, flooding their Websites with multiple requests and disrupting electronic transactions for a short period of time.
Following the attacks, the hackers contacted each bank and claimed a ransom of 20,000 bitcoin ($7 million) from each, threating to take them offline permanently unless their demands were met.
The banks have not acceded to the blackmail, instead strengthening their DDoS defences and working with Greek police and the central bank to track down the extortionists.
A central bank official says further attempts to disrupt the banks' business were made over the weekend, but failed to penetrate the upgraded defensive shields.