Guidance for end users

To learn more about preventing ransomware or other malware from affecting individual devices, read about preventing malware infection.

Guidance for enterprise administrators

Ransomware more than often attacks enterprises than individuals. Following these mitigation steps can help prevent ransomware attacks:

• Keep backups so you can recover data affected by ransomware and destructive attacks. Use controlled folder access to prevent unauthorized applications from modifying protected files.
• Harden internet-facing assets and ensure they have the latest security updates. Use threat and vulnerability management to audit these assets regularly for vulnerabilities, misconfigurations, and suspicious activity.
• Secure Remote Desktop Gateway using solutions like Azure Multi-Factor Authentication (MFA). If you don’t have an MFA gateway, enable network-level authentication (NLA).
• Monitor for brute-force attempts. Check excessive failed authentication attempts (Windows security event ID 4625).
• Turn on cloud-delivered protection and automatic sample submission on Microsoft Defender Antivirus. These capabilities use artificial intelligence and machine learning to quickly identify and stop new and unknown threats.
• Turn on attack surface reduction rules, including rules that block ransomware activity and other activities associated with human adversaries. To assess the impact of these rules, deploy them in audit mode.
• Utilize the Microsoft Defender Firewall and your network firewall to prevent RPC and SMB communication among endpoints whenever possible. This limits lateral movement as well as other attack activities.[NO3] 
• Turn on tamper protection features to prevent attackers from stopping security services.[NO4] 
• Use Office 365 ATP for enhanced [NO5] phishing protection and coverage against new threats and polymorphic variants. Office 365 ATP customers should ensure that Safe Links protection is enabled for users with Zero-hour Auto Purge (ZAP) to remove emails when a URL gets weaponized post-delivery.
• Educate end users about protecting personal and business information in social media, filtering unsolicited communication, identifying lures in spear-phishing email and watering holes, and reporting of reconnaissance attempts and other suspicious activity.