CYB-20 · Cyber security
Ransomware resilience — network segmentation and lateral movement controls in place
Ransomware achieves maximum damage through lateral movement across flat networks. Key controls: network segmentation separating client-data systems from general corporate IT, disabled SMBv1, blocked lateral movement at firewall, and application whitelisting or equivalent on servers holding client data.
Trigger
When this rule fires
Flat network with no segmentation; SMBv1 enabled on any network device; no firewall rules restricting lateral movement; client data accessible from all network segments
Applicability gate
Confirm the entity's role before treating this as a duty
This is a readiness rule mapped to JS2 themes. Its presence in the library does not establish that JS2 applies directly to the firm.
- Insurance Broker: Most independent non-life Category I brokers are not directly in JS2's defined scope. A broker may be directly in scope if it separately meets a listed category, and may face contract or oversight requirements from an in-scope institution. Third-party provisions impose duties on the in-scope financial institution. They do not themselves make every supplier or intermediary directly subject to JS2.
- Uma Binder Holder: UMA or binder-holder status is not itself listed in JS2's definition. Direct scope depends on another listed capacity; insurer contracts and oversight may create evidence requirements. JS2 paragraph 3.3 concerns juristic persons structured under an insurer or designated insurance group; it is not a blanket rule for every independent UMA or intermediary.
- Insurer: An insurer as defined in the Insurance Act is directly in scope of JS2 from 1 June 2025. Apply proportionality and distinguish the insurer's own duty from requirements it places on third parties.
Citation
Mapped source
This control maps to the public instruments below. The mapping does not establish entity applicability.
- Section
- Joint Standard 2 of 2024 / NIST CSF / ISO 27001 A.13
- Legislation
-
- Joint Standard 2 of 2024
Remediation
How to close the gap
Implement network segmentation separating client-facing systems from internal corporate IT. Disable SMBv1 on all devices. Restrict lateral movement at firewall layer. Consider microsegmentation for systems holding PII.
Evidence required
Evidence to prepare if this control applies
- Network architecture diagram showing segmentation
- Firewall rule configuration extract
- SMBv1 disabled verification
- Penetration test confirming lateral movement is blocked