Entry and propagation
Exploitation of SMBv1 flaws addressed by MS17-010; network propagation does not require user interaction.
Targets
Unpatched Windows systems opportunistically, rather than one specific sector.
Impact
More than 200,000 devices across over 100 countries; thousands of UK health appointments and procedures were cancelled.
Defense
Patch SMB, disable SMBv1, segment networks and maintain isolated, tested backups.