It has been reported that BancoEstado, one of Chile’s three biggest banks, was forced to shut down all branches yesterday following a ransomware attack that took place over the weekend. “Our branches will not be operational and will remain closed today,” the bank said in a statement published on its Twitter account on Monday. Details about the attack have not been made public, but a source close to the investigation told ZDNet that the bank’s internal network was infected with the REvil (Sodinokibi) ransomware. The incident is currently being investigated as having originated from a malicious Office document received and opened by an employee. The malicious Office file is believed to have installed a backdoor on the bank’s network. Investigators believe that on the night between Friday and Saturday, hackers used this backdoor to access the bank’s network and install ransomware.