--- name: implementing-conduit-security-for-ot-remote-access-460884e9fb16 description: 'Implement secure conduit architecture for OT remote access following IEC 62443 zones and conduits model, deploying jump servers, MFA-enabled gateways, session recording, and approval-based workflows to control vendor and engineer access to industrial control systems without exposing OT networks directly. ' domain: cybersecurity subdomain: ot-ics-security tags: - ot-security - ics - remote-access - iec62443 - jump-server - zero-trust - conduit - mfa version: '1.0' author: mahipal license: Apache-2.0 nist_csf: - PR.IR-01 - DE.CM-01 - ID.AM-05 - GV.OC-02 mitre_attack: - T1078 - T1190 - T1059 - T0816 - T0836 --- # Implementing Conduit Security for OT Remote Access ## When to Use - When replacing direct VPN connections from IT or vendors into OT control networks - When implementing IEC 62443-compliant conduit architecture for remote access paths - When deploying secure remote access for third-party vendor maintenance of ICS equipment - When building approval-based access workflows for privileged OT system access - When remediating audit findings about uncontrolled remote access to SCADA systems **Do not use** for designing the overall Purdue Model segmentation (see implementing-purdue-model-network-segmentation), for deploying IT-only remote access solutions, or for configuring local console access to PLCs. ## Prerequisites - IT/OT DMZ (Level 3.5) deployed with dual-firewall architecture - Jump server or privileged access management (PAM) platform (CyberArk, BeyondTrust) - Multi-factor authentication (MFA) infrastructure for OT remote access users - Session recording capability for compliance and forensic purposes - Approval workflow system (ServiceNow, ticketing) for access requests ## Workflow ### Step 1: Design Conduit Architecture for Remote Access ```yaml # IEC 62443 Conduit Security Architecture for OT Remote Access # All remote access terminates in DMZ - never passes through to OT directly conduit_architecture: remote_access_conduit: conduit_id: "RA-001" source_zone: "Enterprise IT (Level 4)" destination_zone: "OT DMZ (Level 3.5)" security_level_target: "SL3" components: external_gateway: type: "VPN Concentrator" location: "Enterprise DMZ" ip: "10.200.1.10" protocols: ["IPsec", "SSL-VPN"] authentication: "MFA required (certificate + OTP)" dmz_jump_server: type: "Privileged Access Workstation" location: "OT DMZ (Level 3.5)" ip: "10.10.150.20" os: "Windows Server 2022 (hardened)" controls: - "Local admin accounts disabled" - "USB ports disabled" - "Clipboard transfer disabled by default" - "Session recording enabled (all keystrokes and screen)" - "Maximum session duration: 4 hours" - "Automatic logoff after 15 minutes idle" - "Application whitelisting enforced" ot_access_gateway: type: "Industrial Remote Access Gateway" location: "OT DMZ / Level 3 boundary" ip: "10.10.150.25" controls: - "Only pre-approved destination IPs reachable" - "Protocol-level filtering (RDP, SSH, VNC only)" - "Time-limited sessions with automatic expiry" - "Approval-based access (plant manager must authorize)" data_flow: - step: 1 description: "User authenticates via enterprise VPN with MFA" source: "Remote user" destination: "VPN concentrator" protocol: "IPsec/SSL-VPN" - step: 2 description: "User connects to jump server in OT DMZ" source: "VPN tunnel" destination: "DMZ jump server" protocol: "RDP with NLA" - step: 3 description: "From jump server, user accesses specific OT system" source: "DMZ jump server" destination: "Approved OT target" protocol: "RDP/SSH/VNC" condition: "Only after manager approval and within time window" prohibited_flows: - "Direct VPN tunnel from external to Level 1/2 OT devices" - "Split tunneling allowing internet access during OT session" - "File transfer from jump server to OT without scanning" - "Persistent VPN connections (auto-reconnect disabled)" vendor_access_conduit: conduit_id: "VA-001" source_zone: "Vendor External Network" destination_zone: "OT DMZ (Level 3.5)" security_level_target: "SL3" workflow: request: - "Vendor submits access request via portal (24h advance)" - "Request includes: purpose, target systems, duration, personnel" - "Plant operations manager reviews and approves/rejects" - "Time-limited credentials generated upon approval" session: - "Vendor connects via dedicated vendor VPN gateway" - "MFA authentication (vendor receives OTP via SMS/app)" - "Session lands on vendor-specific jump server (isolated from internal jump)" - "All actions recorded (video + keystroke logging)" - "OT engineer monitors vendor session in real-time" termination: - "Session auto-terminates at approved end time" - "Credentials automatically revoked" - "Session recording archived for 90 days" - "Access log forwarded to SIEM" ``` ### Step 2: Implement Access Control and Monitoring ```python #!/usr/bin/env python3 """OT Remote Access Conduit Manager. Manages approval-based remote access to OT systems through secure conduit architecture with session recording, MFA enforcement, and time-limited access windows. """ import json import sys from datetime import datetime, timedelta from typing import Dict, List, Optional from enum import Enum class AccessRequestStatus(Enum): PENDING = "pending" APPROVED = "approved" REJECTED = "rejected" ACTIVE = "active" EXPIRED = "expired" REVOKED = "revoked" class RemoteAccessRequest: """Represents an OT remote access request.""" def __init__(self, requestor: str, requestor_type: str, purpose: str, target_systems: List[str], duration_hours: int, requested_start: str): self.id = f"OT-RA-{datetime.now().strftime('%Y%m%d-%H%M%S')}" self.requestor = requestor self.requestor_type = requestor_type # "internal_engineer" or "vendor" self.purpose = purpose self.target_systems = target_systems self.duration_hours = duration_hours self.requested_start = requested_start self.status = AccessRequestStatus.PENDING self.created = datetime.now().isoformat() self.approved_by = None self.session_id = None self.audit_trail = [] def approve(self, approver: str, conditions: str = ""): """Approve the access request.""" self.status = AccessRequestStatus.APPROVED self.approved_by = approver self.audit_trail.append({ "timestamp": datetime.now().isoformat(), "action": "APPROVED", "actor": approver, "conditions": conditions, }) def reject(self, rejector: str, reason: str): """Reject the access request.""" self.status = AccessRequestStatus.REJECTED self.audit_trail.append({ "timestamp": datetime.now().isoformat(), "action": "REJECTED", "actor": rejector, "reason": reason, }) class OTConduitManager: """Manages OT remote access conduit security.""" def __init__(self): self.access_requests: Dict[str, RemoteAccessRequest] = {} self.active_sessions: Dict[str, dict] = {} self.policy = self._load_policy() def _load_policy(self) -> dict: """Load remote access policy.""" return { "max_session_hours": 4, "idle_timeout_minutes": 15, "mfa_required": True, "session_recording": True, "clipboard_transfer": False, "file_transfer": "scan_required", "advance_notice_hours": 24, "vendor_escort_required": True, "prohibited_targets": ["SIS-*", "SAFETY-*"], "allowed_protocols": ["RDP", "SSH", "VNC"], "blocked_protocols": ["Telnet", "FTP", "SMB"], } def submit_request(self, request: RemoteAccessRequest) -> str: """Submit a new remote access request.""" # Validate against policy violations = [] if request.duration_hours > self.policy["max_session_hours"]: violations.append( f"Duration {request.duration_hours}h exceeds maximum {self.policy['max_session_hours']}h" ) for target in request.target_systems: for prohibited in self.policy["prohibited_targets"]: pattern = prohibited.replace("*", "") if target.startswith(pattern): violations.append(f"Target {target} is in prohibited list (safety systems)") if violations: print(f"[!] Policy violations found:") for v in violations: print(f" - {v}") return "" self.access_requests[request.id] = request print(f"[+] Access request {request.id} submitted for approval") return request.id def list_pending_requests(self): """List all pending access requests for approval.""" pending = [r for r in self.access_requests.values() if r.status == AccessRequestStatus.PENDING] print(f"\n{'='*65}") print("PENDING OT REMOTE ACCESS REQUESTS") print(f"{'='*65}") if not pending: print(" No pending requests") return for req in pending: print(f"\n Request: {req.id}") print(f" Requestor: {req.requestor} ({req.requestor_type})") print(f" Purpose: {req.purpose}") print(f" Targets: {', '.join(req.target_systems)}") print(f" Duration: {req.duration_hours} hours") print(f" Start: {req.requested_start}") print(f" Submitted: {req.created}") def generate_audit_report(self): """Generate audit report of all remote access activity.""" print(f"\n{'='*65}") print("OT REMOTE ACCESS AUDIT REPORT") print(f"{'='*65}") print(f"Report Date: {datetime.now().isoformat()}") print(f"Total Requests: {len(self.access_requests)}") status_counts = {} for req in self.access_requests.values(): status = req.status.value status_counts[status] = status_counts.get(status, 0) + 1 print(f"\nRequest Status:") for status, count in status_counts.items(): print(f" {status}: {count}") print(f"\nDetailed Audit Trail:") for req in self.access_requests.values(): print(f"\n {req.id} - {req.requestor} ({req.requestor_type})") print(f" Status: {req.status.value}") print(f" Targets: {', '.join(req.target_systems)}") for entry in req.audit_trail: print(f" [{entry['timestamp']}] {entry['action']} by {entry['actor']}") if __name__ == "__main__": manager = OTConduitManager() # Vendor access request vendor_req = RemoteAccessRequest( requestor="John Smith - Siemens Field Service", requestor_type="vendor", purpose="Annual PLC firmware update for S7-1500 controllers", target_systems=["PLC-REACTOR-01", "PLC-REACTOR-02"], duration_hours=3, requested_start="2025-03-15T08:00:00", ) req_id = manager.submit_request(vendor_req) if req_id: manager.list_pending_requests() # Simulate approval manager.access_requests[req_id].approve( approver="Plant Manager - Jane Doe", conditions="OT engineer must shadow the vendor session", ) manager.generate_audit_report() ``` ## Key Concepts | Term | Definition | |------|------------| | Conduit | IEC 62443 controlled communication path between security zones with defined security policies | | Jump Server | Hardened intermediary server in the DMZ through which all remote OT access must transit | | Session Recording | Capture of all screen activity, keystrokes, and commands during a remote access session for audit | | Approval-Based Access | Workflow requiring plant operations manager authorization before remote access credentials are activated | | Vendor Escort | Practice of having an internal OT engineer monitor vendor remote sessions in real time | | Break-Glass Access | Emergency access procedure bypassing normal approval workflow for critical situations | ## Output Format ``` OT REMOTE ACCESS CONDUIT REPORT ================================== Date: YYYY-MM-DD CONDUIT STATUS: Internal Access Conduit: [Active/Inactive] Vendor Access Conduit: [Active/Inactive] ACCESS REQUESTS (Last 30 Days): Submitted: [count] Approved: [count] Rejected: [count] Average Session Duration: [hours] POLICY COMPLIANCE: MFA Enforcement: [100%] Session Recording: [100%] Time-Limited Sessions: [compliance %] Prohibited Target Attempts: [count blocked] ``` --- Source attribution: 26zl Original project: https://github.com/26zl/cybersec-toolkit/blob/2ad2519d437cda1f8a822ef7adc336993601a5ac/.claude/skills/implementing-conduit-security-for-ot-remote-access/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. "Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to the Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution." "Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by the Licensor and subsequently incorporated within the Work. 2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and (b) You must cause any modified files to carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding any notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License. 8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. END OF TERMS AND CONDITIONS APPENDIX: How to apply the Apache License to your work. To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "[]" replaced with your own identifying information. (Don't include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format. Please do not remove or change the license header comment from a contributed file except when necessary. Copyright 2026 mukul975 Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: 26zl Original project: https://github.com/26zl/cybersec-toolkit/blob/2ad2519d437cda1f8a822ef7adc336993601a5ac/.claude/skills/implementing-conduit-security-for-ot-remote-access/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering, Operations Roles: IT Operations, Operations Manager, Security Engineer Specialties: API, DevOps Tools: Beyondtrust, Cyberark, Servicenow Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 81a95131d5b6a1f4eb2fe98ab8729e6bb300652d2b7c9ec54721f418ae6ade2c