### Context
The Lazarus Group initiated their attack on the NHS systems by exploiting a known SMB vulnerability. This vulnerability, identified as CVE-2017-0144, allowed the attackers to gain unauthorized access to the network.

### Insight
The affected systems were primarily those that had not received the necessary security patches. The EternalBlue exploit was used to take advantage of the unpatched systems, highlighting the critical need for timely updates and patches.

### Next Steps
Prepare for potential malware deployment as the attackers have successfully accessed the network.