Which of the IEC 62443 security levels is identified by a hacktivist/terrorist target?

IEC 62443 defines multiple security levels (SLs) tailored to address different types of threats and attackers in industrial control systems.

Security Level 4 (SL4) is designed to protect against sophisticated attacks by adversaries such as hacktivists or terrorists. SL4 involves threats that are targeted with specific intent against the organization, using advanced skills and means.

This level assumes that the adversary is capable of sustained and focused efforts with significant resources, including state-level actors or well-funded groups, aiming at causing widespread disruption or damage.

References

IEC 62443-3-3: System security requirements and security levels.

"Industrial Network Security: Securing Critical Infrastructure Networks for Smart Grid, SCADA, and Other Industrial Control Systems," by Eric Knapp.