Finnish bank OP is continuing to fight off a cascading series of distributed denial of service (DDoS) attacks that began on New Year's Eve.
OP was forced to restrict access to its services from outside the Nordic country as a result of the attack.
The motive for the attack, much less the perpetrators' identity, remain unclear. Unusually the attack is taking place over a time-span of days, rather than hours.
A previously unknown group is using social media to demand payment of a ransom in Bitcoins to call off the attack. CoreSecRUS's claims remain unverified.
The bank has set up a helpline for customers unable to access services online.
OP said that it had got on top of the attack on Sunday...
The denial-of-services attacks seem to be over now. We are paying close attention to the situation. We thank you for your patience. 2/2— OP (@OP_Ryhma) January 4, 2015
... before a fresh flood of junk traffic once again rendered its services unavailable.
Denial-of services attacs seem to continue. Customers abroad may still have difficulties in logging in to OP's online services. 1/2— OP (@OP_Ryhma) January 4, 2015
The above tweet was followed with contact details for customers affected by the outage.
Finnish police are investigating the attack, according to local reports. ®