In this case, the patch was the problem.
Business Insights explains:
Here’s a salutary reminder for all businesses.
Just because a malware outbreak has begun to fade away from the newspaper headlines, doesn’t mean your troubles are over. Many firms can continue to suffer long afterwards.
In late June, a malware attack crippled businesses and critical infrastructure in Ukraine at astonishing speed.
Initially suspected of being a similar ransomware attack to the WannaCry outbreak seen the month before, the malware (variously named as Petya, NotPetya or GoldenEye by security vendors) appears to have been launched through a malicious automatic update to a popular Ukrainian accounting software tool called MeDoc.