US-CERT has received multiple reports of Petya ransomware infections occurring in networks in many countries around the world. Ransomware is a type of malicious software that infects a computer and restricts users’ access to the infected machine until a ransom is paid to unlock it. Individuals and organizations are discouraged from paying the ransom, as this does not guarantee that access will be restored. Using unpatched and unsupported software may increase the risk of proliferation of cybersecurity threats, such as ransomware.
Petya ransomware encrypts the master boot records of infected Windows computers, making affected machines unusable. Open-source reports indicate that the ransomware exploits vulnerabilities in Server Message Block (SMB). US-CERT encourages users and administrators to review the US-CERT article on the Microsoft SMBv1 Vulnerability and the Microsoft Security Bulletin MS17-010 (link is external). For general advice on how to best protect against ransomware infections, review US-CERT Alert TA16-091A. Please report any ransomware incidents to the Internet Crime Complaint Center (IC3).
