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MANILA — Arvic Ramos, an overseas Filipino worker in Kuwait, was cooking dinner one evening when he was notified by his BDO online bank account that it had "successfully" changed passwords.

Alarmed about the activity, Ramos immediately contacted his relatives in the Philippines to get in touch with BDO.

During the call, he also received notifications that P50,000 had been transferred from his account twice into other accounts that were not his.

"Ang hirap-hirap kitain ng pera. Parang nakakapanlumo lang ba," Ramos said, expressing frustration over the unauthorized transactions.

The overseas worker, who denied that other people were aware of his account details, is still in contact with BDO over developments surrounding the incident.

Ramos is one of many Filipinos who, over the weekend, took to social media to reveal that their bank accounts had been hacked.

Manila Bulletin technology editor and cybersecurity advocate Art Samaniego said he initially thought the unauthorized transactions were due to smishing, under which scammers send text messages purported to be from companies in order to trick people into revealing personal information.

But the victims that Samaniego interviewed said they did not click any link from fraudulent text messages.

"May ibang ginawang paraan 'yong mga cybercriminal para manakaw 'yong credential ng mga kababayan natin dito," he told ABS-CBN's Teleradyo.

(The cybercriminals used another way to steal the victims' credentials.)

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Samaniego said the cybercriminals transferred the BDO clients' funds to Unionbank accounts, which were then used to buy Bitcoin from the cryptocurrency market.

On Sunday, the Bangko Sentral ng Pilipinas (BSP) said it was monitoring the surge of hacking complaints, adding that it was already coordinating with BDO and Unionbank to resolve the issue.

• BSP says coordinating with BDO, UnionBank on alleged hacking complaints

"We are in close coordination with BDO as well as [Unionbank of the Philippines] on this incident to ensure that remedial measures are being undertaken, including reimbursement of affected consumers," the central bank said in a statement.

BDO, in a separate statement, said it was already taking "additional security controls" to protect bank credentials and that it would reimburse the losses of affected clients.

Unionbank President Edwin Bautista said the bank had frozen less than 10 accounts that received funds from BDO, adding that legal steps would be taken against those who use their accounts for criminal activities.

— With a report from Reuters