Major firms were left reeling from yet another cyber-attack as a ransomware virus spread across the world.
Among the major corporate names known to have been targeted were oil and gas giant Rosneft, Danish shipping firm Maersk, advertising agency WPP, pharmaceutical company Merck and confectionary group Mondelez.
It is thought to be similar in nature to last month´s Wannacry malware virus attack, which caused widespread disruption to organisations around the world.
The latest ransomware virus is thought to use the same flaw in the Windows operating system as was exploited by Wannacry.
In an echo of the Wannacry attack, the ransomware locks computers and delivers an onscreen message, demanding users pay $300 in Bitcoins to regain access to their files.
It´s thought that as many as 80 companies based in the Ukraine and Russia were infected in the first wave of the latest attack, though it wasn´t long before firms in other locations across the world felt its impact.
Ukraine´s Chernobyl nuclear power plant was reported to be monitoring radiation levels manually as its Windows-based sensors had been turned off.
ExPetr or Petya?
Security firm Kaspersky Lab dubbed the ransomware “ExPetr”, claiming it was a new ransomware. However, security experts at Symantec said they believed the latest malware to be a variant of known-ransomware Petya.
In common, with Wannacry, the latest malware attack is understood to exploit the so-called EternalBlue flaw in Microsoft Windows.
The initial share price impact on those companies affected appeared muted. WPP shares were little changed, down by just 0.55% in early trading on Wednesday. Rosneft was -0.82% lower.