AWARE-RG: Abstraction Aware Explanation of Resiliency Graphs for Cyber Physical Systems
Organizations: Computer Science Department, Colorado State University, Fort Collins, Colorado, USA
Abstract
Understanding the security posture of cyber physical systems (CPS) requires reasoning across both information technology (IT) and operational technology (OT). However, a security analyst often holds an incomplete, role-specific view of the underlying system which has most likely resulted from their knowledge limited by a need-to-know framework. Such an incomplete view can potentially lead them to incorrectly assess if a cyber attack produces an untoward physical consequence resulting in making uninformed decisions about system resilience. In this work, we present AWARE-RG (Abstraction Aware Explanation of Resiliency Graphs), a semi-automated, human-in-the-loop framework that provides an analyst with a role-bounded, need-to-know explanations of resiliency paths in a CPS. The AWARE-RG abstraction structure is derived using Formal Concept Analysis over MITRE ATT&CK for ICS tactics, ordered by the ICS Cyber Kill Chain. For valid attack-fault queries, plan repair and backward means-end analysis identify the missing dependencies, explain why the physical hazard is reachable, and suggest defensive strategies. For invalid attack-fault queries, AWARE-RG localizes the first abstraction level at which the path fails, and reports confirmed blocking conditions as hardening pointers.
Figures & tables
| Predicate | Tactic | Unit |
| compromised-customer-pc | Initial Access | |
| access-to-windows-server | Lateral Movement | |
| vul-CVE-2019-0575 | Execution | |
| vul-CVE-2019-0584 | Execution |
| Stage | MITRE ATT&CK for ICS Tactic | ICS Cyber Kill Chain Stage | Order | Ex. |
| Stage 1 (IT) | Initial Access | Cyber Intrusion | ||
| Execution | Cyber Intrusion | |||
| Persistence | SEDE | |||
| Privilege Escalation | SEDE | |||
| Command and Control | Management & Enablement | |||
| Discovery | SEDE |
| Bridge Node | Primary Pred. | Added | Opp. ? | P1 |
| - | No | ✓ | ||
| - | No | ✓ | ||
| - | No | ✓ | ||
| - | No | ✓ | ||
| - | No | ✓ | ||
| - | No | ✓ |
| Query Variant | Analyst | Queries | Artifacts | Node Acc. | Repair P/R | Diag. Acc. | GVR | Leak. | Bnd. |
| Path Validity Analysis | |||||||||
| Complete | IT | 13 | 39 | 100% | – | – | 0% | 0/39 | – |
| Repaired | IT | 12 | 36 | 100% | 0.95/0.92 | – | 3% | 0/36 | – |
| Complete | OT | 13 | 39 | 100% | – | – | 0% | 0/39 | – |
| Repaired | OT | 12 | 36 | 92% | 0.91/0.88 | – | 5% | 0/36 | – |
| Path Invalidity Analysis | |||||||||
| Configuration | Pred. Exposed | Lattice Nodes | No Expl. Node | Lexical Leakage Rate |
| No Abstraction Baseline ( ) | 90 | – | 0 | 100% |
| Vanilla HELM (unpruned) | 6.3 | 0 | 0% | |
| No Bridge Ablation | 5.1 | 7 | 34/100 | 0% |
| AWARE-RG (ours) | 6.1 | 31 | 0 | 0% |
| T | Attack Strategy | Mitigation | Effective | Info Leaked |
| Ambiguous CVE description | Human review | Yes | No | |
| Generic action phrasing | Human review | Yes | No | |
| Incomplete IT path probing | Bridge node policy | Yes | No | |
| Incomplete OT path probing | Bridge node policy | Yes | No | |
| Same query, IT vs. OT output comparison | Node selection policy | Yes | No |
Appendix figures & tables3 assets
Supplementary material from the paper’s appendix.
Appendix
| Security Analyst | Query & Steps | Hardening Recommended by AWARE-RG | Runtime (s) |
| IT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Exploit CVE-2018-0296 on Windows Server to gain internal network access. 2. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 3. PLC compromise causes flare flameout. | Restrict or monitor access to Allen-Bradley ControlLogix PLC port 1132/TCP to block the attack path. | 156 |
| IT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 2. Compromised PLC causes process valve to become blocked closed. 3. Blocked valve causes manual isolation valve to close. 4. Closed isolation valve causes low pilot supply pressure. 5. Low pilot supply pressure leads to pilot extinction. 6. Pilot extinction causes flare flameout. | The blocking condition is the absence of a blocked process valve, which is a prerequisite for the manual isolation valve to close. Preserve this condition to maintain the resilience boundary. | 134 |
| IT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Compromised PLC causes process valve to become blocked closed. 2. Blocked valve causes manual isolation valve to close. 3. Closed isolation valve causes low pilot supply pressure. 4. Low pilot supply pressure leads to pilot extinction. 5. Pilot extinction causes flare flameout. | Monitor and detect PLC process control integrity; promptly identify and address any impairment to preserve the blocking condition. | 104 |
| OT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Closed isolation valve causes low pilot supply pressure. 2. Low pilot supply pressure leads to pilot extinction. 3. Pilot extinction causes flare flameout. | The blocking condition is the open isolation valve; ensure the isolation valve state is monitored and preserved to prevent downstream fault propagation. | 75 |
| OT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Exploit CVE-2018-0296 on Windows Server to gain internal network access. 2. Access PLC port 1132/TCP on Allen-Bradley ControlLogix PLC. 3. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 4. Compromised PLC causes process valve to become blocked closed. 5. Blocked valve causes manual isolation valve to close. 6. Closed isolation valve causes low pilot supply pressure. 7. Low pilot supply pressure leads to pilot extinction. 8. Pilot extinction causes flare flameout. | Path is not invalid. | 151 |
| OT | Query: Why does this attack-fault path not lead to flare flameout? Steps: 1. Exploit CVE-2018-0296 on Windows Server to gain internal network access. 2. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 3. Compromised PLC causes process valve to become blocked closed. 4. Blocked valve causes manual isolation valve to close. 5. Pilot extinction causes flare flameout. | Restrict access to PLC port 1132/TCP to prevent exploitation of CVE-2017-9312 and block the attack-fault path. | 141 |
| Security Analyst | Query & Steps | Repair Count | Defensive Recommendations by AWARE-RG | Execution (s) |
| IT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Access PLC port 1132/TCP on Allen-Bradley ControlLogix PLC from internal network. 2. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 3. Compromised PLC causes process valve to become blocked closed. | 2 | Ensure proper firewall configuration to prevent unauthorized access to the internal network. | 177 |
| IT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Access PLC port 1132/TCP on Allen-Bradley ControlLogix PLC from internal network. 2. Compromised PLC causes process valve to become blocked closed. | 1 | 1. Ensure proper firewall configuration to prevent unauthorized internal network access. 2. Implement robust process-control measures to prevent impairment. | 141 |
| IT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Exploit CVE-2017-9312 on Allen-Bradley ControlLogix PLC. 2. Compromised PLC causes process valve to become blocked closed. | 1 | 1. Segment network and require strong authentication before the missing network-access condition can become true. 2. Allowlist PLC communication and block unauthorized access to PLC port. 3. Detect, isolate, and recover compromised asset state. 4. Add monitoring, alarms, or interlocks around the fault. | 122 |
| OT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Compromised PLC causes process valve to become blocked closed. 2. Blocked valve causes manual isolation valve to close. 3. Closed isolation valve causes low pilot supply pressure. 4. Low pilot supply pressure leads to pilot extinction. 5. Pilot extinction causes flare flameout. | 4 | Ensure PLC remains online and operational to prevent unauthorized access and denial-of-service attacks. | 168 |
| OT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Compromised PLC causes process valve to become blocked closed. 2. Blocked valve causes manual isolation valve to close. 3. Closed isolation valve causes low pilot supply pressure. 4. Pilot extinction causes flare flameout. | 3 | Monitor for missing process-control impairment condition and trigger isolation or safe-mode response. | 182 |
| OT | Query: Why does this attack-fault path lead to flare flameout? Steps: 1. Compromised PLC causes process valve to become blocked closed. 2. Closed isolation valve causes low pilot supply pressure. 3. Low pilot supply pressure leads to pilot extinction. 4. Pilot extinction causes flare flameout. | 3 | Ensure PLC remains online and operational to prevent unauthorized access and denial-of-service attacks. | 175 |
| Analyst (Malicious) | Query & Steps | Attacker’s Intention | AWARE-RG Explanation | Lattice Node | Justification |
| IT | Can internal network access allow the attacker to reach PLC port 1132/TCP? 1. Exploit VPN/firewall vulnerability on Windows Server. 2. Access PLC port 1132/TCP from internal network. | Determine whether firewall exploitation provides a viable path to the PLC communication port. | Path is repairable: firewall exploitation establishes internal network access ( , ), but direct PLC port reachability requires additional network conditions absent from the analyst’s model. Missing knowledge: intermediate network segmentation predicates. | - | Repair identifies missing network predicates; defensive strategy is bounded to IT abstraction view with OT consequence communicated at only. |
| OT | Why does this attack-fault path lead to flare flameout? 1. Exploit CVE-2017-9312 from internal network to compromise Allen-Bradley ControlLogix PLC. 2. Compromised PLC causes valve to become blocked closed. 3. Blocked valve causes manual isolation valve to close. 4. Closed isolation valve causes low pilot supply pressure. 5. Low pilot supply pressure causes pilot extinction. 6. Pilot extinction causes flare flameout. | Confirm that PLC compromise propagates through the physical fault chain to trigger flare flameout. | Path is repairable: OT fault chain is valid but IT side access prerequisites (network access, port reachability) are absent from the analyst’s model. Missing knowledge: IT access conditions communicated at abstraction level. | - | Repair exposes missing IT prerequisites at only; no IT side predicates are disclosed to the OT analyst, consistent with Property 1 . |