In these two day, many Windows users affected by the malicious “WannaCrypt” software. Microsoft posted "Customer Guidance for WannaCrypt attacks", the steps to stay protected. Additionally, Microsoft are taking the highly unusual step of providing a security update for all customers to protect Windows platforms that are in custom support only, including Windows XP, Windows 8, and Windows Server 2003. Windows 10 were not targeted by the attack up to now.
Link ~ Microsoft TechNet - Customer Guidance for WannaCrypt attacks