Three banks were on alert all weekend after hackers made attempts to intrude into their security systems. The National Intelligence Service, Cyber Crime Squad of Greece and Bank of Greece worked with bank officials all weekend in an attempt to stall off the hackers, who are believed to be coming from Russia, say sources. Over 30 people have been trying to get control of the banks for the last three 24-hour periods and are seeking bitcoin for ransom so as not to cause damages in banking transaction systems.