A major cyber attack by a ransomware virus which started in Ukraine and Russia has unfolded across the world, targeting giant organizations, firms and infrastructure in several countries.
The Tuesday cyber attack initially hit IT networks in Ukraine and Russia and then spread to Denmark, France, Britain and the US.
Some of the victims of the cyber attacks said their computers were blocked and received a message which demanded $300 worth of the Bitcoin to restore access to their files.
"If you see this text, then your files are no longer accessible, because they have been encrypted. Perhaps you are busy looking for a way to recover your files, but do not waste your time. Nobody can recover your files without our decryption service," the message said.
According to IT security experts, the virus is a modified version of the so-called Petya ransomware, similar to WannaCry virus, which targeted 200,000 computers in more than 150 countries in May and demanded to receive money from victims in exchange for their data.
The malware makes computers inoperable by encrypting their hard drives and demands ransoms in exchange for a digital key to restore access.
The cyber attack first hit computer networks of Ukraine’s central bank and several other financial institutions, the state energy distributor and Kiev's main airport on Tuesday.
The Ukrainian government described the incident as the worst cyber attack in the history of the country, with the secretary of Ukraine’s National Security Council alluding to signs of Russian involvement in the attack.
However, Russia turned out to be another victim of the attacks with the country’s biggest oil company, Rosneft, and metal maker firm Evraz being targeted.
Moscow-based cyber security firm Group IB said hackers had used code developed by the US National Security Agency (NSA) which was leaked and then used in the global cyber attack by WannaCry ransomware in May.
Later in the day, Danish sea transport company Maersk, British advertising giant WPP and several hospitals across the UK, French industrial group Saint-Gobain and US pharmaceutical giant Merck reported similar attacks against their networks.
IT experts expect more countries to be affected by the new cyber attack.