It's business as usual for US military's social media sites despite the fact that hackers broke into the Pentagon's Twitter account.

Users in Brazil, Russia and Italy were most frequently attacked by financial malware, according to Kaspersky Lab’s latest monthly report on online threats in the banking sector.

In the reporting period from April 19 to May 19, 2014, Kaspersky Lab solutions blocked 126 600 attempts on computers to launch malware capable of stealing money from users of online banking accounts in these three countries – this was more than a third of the total number of users attacked by banking malware worldwide.

As a rule, cybercriminals try to steal users’ bank card details with the help of the specialised Trojan programmes. From mid-April to mid-May, Zeus (Trojan-Spy.Win32.Zbot) was once again the most widespread banking Trojan.

According to Kaspersky Lab’s research, the programme was involved in 198 200 malware attacks on online banking clients. About 82 300 people were attacked by Trojan-Banker.Win32.ChePro and Trojan-Banker.Win32.Lohmys – malicious programmes mainly spread via spam emails with the subject “Internet bank charges”.

Yet another method of stealing banking data is phishing attacks. During the reporting period, Kaspersky Lab solutions blocked 21.5 million of these attacks and almost 10 percent of them (about 2 million) targeted users’ bank card details.

The reporting period was marked by consequences of one particular event that seriously jeopardised the security of online payment systems, namely a vulnerability previously found in the popular encryption library OpenSSL.

The bug allows attackers to gain unauthorised access to the buffer memory of a vulnerable device, be it a smartphone, personal computer or server.

The Heartbleed vulnerability leaves no trace and it is still not known what data was stolen and in what volumes. However, most companies that performed online transactions using the vulnerable version of OpenSSL have recommended that their clients change their account passwords and closely monitor any unusual activity.

“The appearance of the Heartbleed vulnerability initiated a series of leaks of all kinds of data in various business fields. This was due to the fact that this vulnerability contained the cryptographic OpenSSL library which is used in different software including banking software,” commented Sergey Golovanov, Principal Security Researcher at Kaspersky Lab.

“The absence of an official library update for several hours after the vulnerability was detected and the slow reaction of IT security services at financial institutions in installing the update led, in some instances, to the leak of bank transaction data. That’s why, in the coming months, we can expect a surge of fraudulent transactions.”