Spanish Police and European Union law enforcement agency Europol on Wednesday arrested a cybercrime gang comprising Russians and Ukrainians that allegedly stole over one billion euros from financial institutions across the world during the last five years.

The alleged mastermind of the gang, a Ukranian identified as Denis K, was nabbed from Alicante, a coastal city located 350 kilometres capital Madrid, a statement issued by the Spanish authorities said.

The police also arrested other suspected members of the gang, whose activities were monitored by the law enforcement agencies for several months.

During the raid in Alicante, the police seized two luxery cars and jewels worth 500,000 euros.

Authorities said the search for other members of the gang is underway.

The gang targeted more than 100 financial institutions in over 40 countries using malware like Carbanak and Cobalt, primarily in Russia, where almost all of the mainstream banks were attacked and half of them lost money.

The gang also carried out large-scale cyber attacks in Belarus, Kazakhstan, Azerbaijan, Taiwan and Ukraine.

The gang targeted more than 100 financial institutions in over 40 countries using malware like Carbanak and Cobalt, primarily in Russia, where almost all of the mainstream banks were attacked and half of them lost money

According to Europol, the gang used to send phishing emails containing a malicious attachment to the bank employees to get remote access to internet banking network and servers controlling ATMs.

ATMs were instructed to dispense cash, which was collected by organized groups of the gang.

“They’re unusual in how slow and methodical they are and how organized they are,” said Ross Rustici, a senior director at Boston-based digital security firm Cybereason.

.“Other groups use similar techniques in isolation, but nobody before them had strung all those things together on such a scale,” he added.

Police said that the gang converted ihe cash into bitcoin, which were then used for purchasing houses, vehicles and other property in Spain and other countries.

“That’s usually what happens with these who are very good on the network side, they make mistakes on the money side,” Rustici said. “You can’t buy a nice villa on the Mediterranean with cryptocurrency. Or at least not yet.”