Practical Guide to Cloud Network Separation Exceptions under the 2026 Electronic Financial Supervisory Regulations

Practical Guide to Cloud Network Separation Exceptions under the 2026 Electronic Financial Supervisory Regulations

"We want to use the cloud, but network separation won't let us." That is the line you hear most often in the field at financial institutions and fintechs. In practice, though, the real problem is not that you cannot use the cloud—it is that you do not know which conditions to meet, what to submit, and when. This article follows the Electronic Financial Supervisory Regulations in force since 2026-07-15 (FSC Notice No. 2026-29; National Law Information Center, checked 2026-10-04). This article goes beyond parsing the regulation text and lays out checklists and CSP implementation architectures that practitioners can put to work immediately.

Re-reading the network separation provisions from a cloud perspective

Read abstractly, the network-separation obligations in the Electronic Financial Supervisory Regulations sound like "block everything." Breaking the issues down from a cloud-adoption perspective makes decisions much easier.

The regulation keeps separation as the rule and lists specific exceptions. To use one, you must be able to demonstrate that its conditions are met.

How far do the current exceptions go?

These are the exceptions written into the current provisions. This is not an across-the-board loosening—each is an exception with conditions and approvals attached. Check FSC and FSS announcements separately for relaxations outside the regulation text (such as regulatory sandboxes).

Practitioner tip: The starting point for applying an exception is data classification that first defines whether the system is critical work. If classification is ambiguous, that is the first thing that will trip you up at the supervisory stage.

Filing and reporting procedure checklist

Signing a usage contract with a CSP is not the end. Missing a reporting deadline is itself a finding.

• Before use: Perform a criticality assessment and business impact analysis
• Before use: Assess the CSP's soundness and security (do it yourself or use the assessment by an incident response institution under Art. 37-6(1), Art. 14-2(3)); for non-critical work, only the mandatory items in Annex 2-2
• Before use: Have the information security committee review and resolve on the assessment results, business continuity plan and security measures (Art. 14-2(2))
• Report: Report to the FSS Governor within 3 months of signing a new usage contract or starting new work under an existing contract, and keep the documents up to date (Art. 14-2(4))
• Documents to submit: The report form and attachments are set by the FSS Governor (Art. 14-2(5)); check the FSS forms
• Documents to submit: Network separation architecture diagram and evidence of logical separation controls
• After the fact: Also report within 3 months on material CSP changes (merger, split, re-outsourcing, etc.), failure to meet key contract terms, or material changes to assessments or security measures (Art. 14-2(4) items 2–4); retain periodic inspection results internally
• Linkage: Prepare a mapping table between the Annex 2-2 assessment items and internal controls

The four stages and who does what

Grouped in order, the checklist above comes down to four stages. Deciding up front who owns each stage reduces bottlenecks such as slow collection of CSP materials.

How the procedure changed: Before the amendment of 2022-11-23 (in force 2023-01-01), using the cloud for critical business required prior reporting 7 business days before use. The amendment replaced this with after-the-fact reporting within 3 months of signing a new service contract or a material change to one, and simplified the required documents (FSC press release). A later amendment on 2025-02-05 added processing new work under an existing service contract as a reporting trigger (Art. 14-2(4)1). Older material that assumes prior reporting or "submission before use" does not match the current regulation.

Logical network separation architecture by CSP

There are three core design principles: (1) logically separate the business network and internet network with VPCs/subnets; (2) control a single entry point with Bastion + PAM; (3) Zero Trust that verifies every access.

[Admin] → [PAM/Bastion(MFA)] → [Private Subnet: business servers]
                                       │
                          [NAT GW] → Restricted outbound only
[Internet-network VPC] ──(transfer control & approval)── [Business-network VPC]
        Log all traffic → SIEM integration

The control concepts are the same regardless of CSP. You only need to map the service names.

The key is not to attach an internet gateway to the business-network subnet, and if external communication is needed, whitelist only approved paths (NAT, Endpoint).

Top 5 frequently cited findings and how to respond

The findings that come up repeatedly in actual inspections are well known.

1. Insufficient access-control logs → Integrate Flow Logs and Bastion session records into SIEM; comply with minimum retention periods
2. No control over inter-network data transfer → Apply an approval workflow and DLP to VPC Peering and transfer paths
3. Inadequate privilege management → IAM least privilege, periodic privilege recertification, and removal of shared accounts
4. Unclear ownership of encryption key management → The financial institution retains KMS key ownership and revocation rights (consider BYOK)
5. Missed usage-reporting deadlines → Register a reporting calendar as soon as the contract is signed; automate change-report triggers

Technically Verifying a Logical Network Separation Setup

Regulatory inspections and internal audits look at whether actual settings match the documents, not just the design. In the cloud a single console action can change a path, so you need a routine that queries settings and keeps them as evidence.

Common causes of drift

• An internet gateway route (0.0.0.0/0) is added to a route table of a subnet designated as the internal business network
• An allow-all (0.0.0.0/0) inbound rule added during an incident is never removed
• VPC peering or sharing between dev and production accounts appears in a form not in the documents

Checks (AWS example)

# route tables with a default route to an internet gateway
aws ec2 describe-route-tables \
  --query "RouteTables[?Routes[?GatewayId!=null && starts_with(GatewayId,'igw-') && DestinationCidrBlock=='0.0.0.0/0']].{id:RouteTableId,subnets:Associations[].SubnetId}"
# security groups with allow-all inbound
aws ec2 describe-security-groups \
  --filters Name=ip-permission.cidr,Values=0.0.0.0/0 \
  --query "SecurityGroups[].{id:GroupId,name:GroupName}"
# VPC peering
aws ec2 describe-vpc-peering-connections --query "VpcPeeringConnections[].{id:VpcPeeringConnectionId,status:Status.Code}"

On Azure and GCP, query route tables, NSG/firewall rules, and peering from the same angle.

Prevention

• Monitor these conditions continuously with AWS Config rules or policy tools (e.g., OPA, cloud security posture management) and keep alerts and change history on violations.
• Keeping monthly check results gives you evidence for reporting and inspections. Check the exception requirements themselves against the Electronic Financial Supervisory Regulations and guidance from the Financial Services Commission and Financial Supervisory Service.

References: primary sources (statutes and supervisory authorities)

Judgments on network-separation exceptions and relaxations presuppose interpretation of the regulation text. Cross-check the latest provisions and supervisory interpretations directly from the primary sources below.

• Full text of the Electronic Financial Supervisory Regulations (version in force since 2026-07-15): National Law Information Center
• Financial sector cloud security assessment: Financial Security Institute

Article numbers in the regulations may change with revisions, so always cite the current provisions as confirmed in the original text in reports and internal approval memos.

Frequently asked questions (FAQ)

Q. Can you put all workloads in the cloud with logical network separation alone? A. No. The R&D exception only applies when no unique identifiers or personal credit information are processed, and any cloud use goes through the Art. 14-2 procedure (criticality assessment, CSP assessment, committee resolution, reporting) regardless of criticality. If you process unique identifiers or personal credit information, the systems must be located in Korea.

Q. By when must the usage report be filed? A. Report to the FSS Governor within 3 months of the triggering event, such as signing a new usage contract (Art. 14-2(4)). The criticality assessment, CSP assessment and committee resolution come before use.

Q. What should you take care of first when preparing for supervision? A. Data/work criticality classification and access-control logs. If classification is clear and logs are integrated into SIEM, you can prevent most findings.

Sources · checked 2026-10-06

• National Law Information Center, Electronic Financial Supervisory Regulations (in force 2026-07-15, FSC Notice No. 2026-29) — Art. 14-2 (cloud usage procedure, report within 3 months, para. 7 CSP data-center exemption and domestic location), Art. 15(1) items 3 and 5 (network separation and exceptions), Art. 8-2 (information security committee), Arts. 13 and 19 (data protection, key management)
• FSC press release, amendment to the Electronic Financial Supervisory Regulations approved (2022-11-23) — prior reporting (7 business days before) for critical-business cloud use replaced by after-the-fact reporting (within 3 months), simplified documents, in force 2023-01-01