The ransomware is linked to a leaked vulnerability originally kept by the National Security Agency . Major corporations across the world have been hit Attack.Ransom by a wave of ransomware attacks Attack.Ransom that encrypt computers and then demand Attack.Ransom that users pay Attack.Ransom $ 300 to a bitcoin address to restore access . While countries across Europe — the United Kingdom , Ukraine , Spain and France , to name a few — were hit hardest by the outbreak , the virus has now spread to the United States . Today , one of the largest drug makers in the U.S. , Merck , reported being infected by the malware , as did the multinational law firm DLA Piper , which counts more than 20 offices in the U.S. Heritage Valley Health Systems , a health care network that runs two hospitals in Western Pennsylvania , also confirmed in a statement to Recode on Tuesday that it was a victim of the same ransomware attack Attack.Ransom that has spread around the globe . At least one surgery had to be postponed because of the hack , according to a woman interviewed by Pittsburgh Action News 4 . The malware , which has been dubbed NotPetya , has been confirmed by multiple security firms to resemble the WannaCry ransomware attack Attack.Ransom , which in May infected hundreds of thousands of computers by taking advantage of a National Security Agency hacking tool called Eternal Blue . That exploit was leaked last April by a hacker or group of hackers called ShadowBrokers . Eternal Blue takes advantage of a vulnerability in the Windows operating system , for which Microsoft issued Vulnerability-related.PatchVulnerability a patch earlier this year . Not all Windows users installed the update — hence one of the reasons WannaCry was able to spread . “ Our initial analysis found that the ransomware uses multiple techniques to spread , including one which was addressed Vulnerability-related.PatchVulnerability by a security update previously provided for all platforms from Windows XP to Windows 10 , ” Microsoft said in a statement to Recode . Microsoft further advised users to exercise caution when opening files in emails from unknown sources , since malware is often spread through email attachments . Microsoft also noted that its antivirus software is capable of detecting and removing the ransomware . Ukraine appears to have been the country most affected by today ’ s ransomware outbreak , according to a chart shared in a tweet by Costin Raiu , the director of a global research team with Kaspersky Lab .