These updates were automatically delivered to all Microsoft free antimalware products, including Windows Defender Antivirus and Microsoft Security Essentials.
You can download the latest version of these files manually at the Malware Protection Center.
Based on our investigation, this new ransomware shares similar codes and is a new variant of Ransom: Win32/Petya.(Note: We have published a follow-up blog entry on this ransomware attack.We have new findings from our continued investigation, as well as platform mitigation and protection information: Windows 10 platform resilience against the Petya ransomware attack.) On June 27, 2017 reports of a ransomware infection began spreading across Europe.Vulnerabilities are weaknesses in software that enable an attacker to compromise the integrity, availability, or confidentiality of the software or the data that it processes.Some of the worst vulnerabilities allow attackers to exploit the compromised system by causing it to run malicious code without the user’s knowledge.