MOSCOW, October 15. /TASS/. Russian-speaking hackers earned an estimated $2.5 billion between mid-2013 and mid-2014 using criminal tactics to attack Russian banks.

According to security researchers from Russian cybercrime investigations firm Group-IB, about 4% of financial institutions in the country were hit by cyber attacks over 12 months.

In 70% of cases, banks learnt about these incidents from external specialists, said Dmitry Volkov, head of Group-IB's investigation department. And only in 3% of cases had IT experts detected a hacker attack in time to take immediate action.

Even companies demonstrating a high level of information security control did not always manage to avoid problems, Volkov said.

As the threat of security breaches continues to grow, the types of attacks are becoming more diverse and complex. Traditional distributed denial-of-service (DDoS) attacks are now giving way to more sophisticated methods.

An increasing number of cyber attacks are targeting bank cash machines. Cybercriminals install malicious software onto the machine using the ATM's CD drive. Once the malware is installed on the machine, the cybercriminal can enter a special code to unlock the machine and dispense the cash.