According to the IEC 62443 standard, your security level is 4 .

According to the OT Security 7.6 Architect study guide regarding IEC 62443 Security Levels :

Security Level 4 (SL 4) Definition : This level provides " Protection against intentional violation using sophisticated means with extended resources, specific skills, and high motivation " .

Real-World Application : The study guide specifically notes: " If you are facing a syndicate of cyber extortionists with extensive resources and capabilities, then you should strive for security level 4 " .

Comparison to other levels :

SL 1 : Protection against " casual or unintentional system violation " .

SL 2 : Protection against " intentional violation using simple means with low resources " .

SL 3 : Protection against " intentional violation using sophisticated means with moderate resources " .