A new ransomware is making its rounds across the globe. Known as Petya, the attack started in Ukraine and has since spread to US and Europe.

It is reported that the malware has spread through large firms including advertiser WPP, food company Mondelez, legal firm DLA Piper and Danish shipping and transport firm Maersk.

Similar to Wannacry, the Petya ransomware takes over the computer and demands a $300 ransom paid in Bitcoin. The malware spreads across computers through the use of EternalBlue vulnerability in Microsoft Windows machines, or through two Windows administrative tools.

According to the Ukrainian Cyber Police, the attack appears to have been seeded through a software update mechanism built into an accounting program that companies working with the Ukrainian government need to use. Many Ukrainian organisations were affected, including government, banks, state power utilities and Kiev’s airport and metro system. The radiation monitoring system at Chernobyl was also taken offline, forcing employees to use hand-held counters to measure levels at the former nuclear plant’s exclusion zone.

As of now, it is unclear who is behind the attack, but researchers noted that the attack seems to carry a “deliberate, malicious, destructive attack or perhaps a test disguised as ransomware”, aimed at the Ukrainian government.