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This research investigates the security implications of different IoT deployments and develops an algorithm to find the optimal deployment with minimum security risk through attack graph analysis.
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Deployment Optimization of IoT Devices through Attack Graph Analysis Noga Agmon Supervisors: Dr. Rami Puzis, Dr. Asaf Shabtai Dept. of Software and Information Systems Engineering, Ben-Gurion University of the Negev, Israel
Research Goals • Investigate the security implications of different IoT deployments. • Develop an algorithm to find the deployment with the minimum security risk (optimal deployment).
Example Attack Path Attack Graph
Attack Graph – Background • Model of a computer network that encompasses computer connectivity, vulnerabilities, assets, and exploits. • Used to represent collections of complex multi-step attack scenarios. • Security analyst can assess the risks of potential intrusions and devise effective protective strategies by analyzing the attack graph. • Three main stages: (1) network and vulnerabilities scanning, (2) attack graph modeling, and (3) attack graph analysis.
Vul1 Attacker in Vul2 Attack Graph - Structure Exp Exp 1 3 2 AttackerControl AttackerControl 4 5 Vul3 6 7 8 Exp Exp 10 9 Vul4 AttackerControl 12 11 13 Exp 14 AttackerControl
Vul1 Attacker in Vul2 Attack Graph - Structure Exp Exp 1 3 2 AttackerControl AttackerControl 4 5 Vul3 6 7 8 Exp Exp 10 9 Vul4 AttackerControl 12 11 13 Attack Path Exp 14 AttackerControl
IoT Attack Graphs • IoT devices introduce additional challenges to attack graphs: • Diverse physical locations, • Variety of short-range communication protocols, • Cyber-physical capabilities of the devices, • Mobility, • etc.
IoT Attack Graphs • Short-range communication protocols – The number of protocols in the device can influence the security. • An hacker can take advantage of a compromised device and use the other protocols as entry points to the network. • Physical location – The location of an IoT device can bridge between networks through short-range communication protocols.
IoT Attack Graphs • We augmented the attack graph to model short-range communication protocols. • We define possible connectivity between devices based on their locations and supported protocols. • The connection range of IoT device deployed in a location can be estimated based on the radio specification of the device.
Risk Score • A way to quantify the security of a network. • There are many methods to measure the security risk using an attack graph. • For example, likelihood of attack, number of exploits needed, etc.
Our Risk Score • The risk increases as the possible attack paths become shorter and as more of the shortest attack paths are added. • We choose to calculate the shortest attack paths, taking their length and quantity into consideration. • Our method for calculating risk score is sensitive to small changes in different deployments.
Problem Definition • We solved two optimization problems. • Full Deployment with Minimal Risk (FDMR): all required IoT devices should be deployed with minimal security implications. • Maximal Utility without Risk Deterioration (MURD): the maximal number of IoT devices that can be deployed without increasing the security risk of the network.
Heuristic Search Empty Deployment Full Deployment 1 Full Deployment n Full Deployment 2 Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Heuristic Search • We used depth-first branch and bound (DFBnB). • DFBnB prunes subtrees of the search space where there is no point to expand. • In order to perform pruning more frequently and thus accelerate the search process, DFBnB uses a heuristic function.
Heuristic Function • In an informed way, heuristics help the algorithm guess which child out of all of the node's children will lead to the goal. • A heuristic is an estimation of the cost of the path from node to a goal node.
Our Heuristic Function • Table of risk scores containing the risk scores for each IoT device in each possible location. • For each deployment, we update the table, removing the IoT device that was deployed or not allowed to be deployed.
Our Heuristic Function • FDMR: Chooses the cell with the highest risk score in the table. • MURD: Counts the number of IoT devices with the same risk score as the root state. Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Experimental Setup • We solved the two problems as optimization problems. • Organization Network – We took a real network organization consisting of 24 hosts. • Simulations – We simulated the IoT devices and the physical locations of the hosts.
Experimental Setup • Number of Executions – We executed the experiments forty times, simulating different physical locations each time. All results are the average results of all executions. • Random Deployment – For comparison, we also ran both problems randomly as a baseline. • FDMR – Randomly deployed all required IoT devices. • MURD – Added a device randomly and computed the risk score. We started with no IoT devices deployed and continued until full deployment. • This random baseline was executed the same number of times as our algorithm (forty times). Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Results • The risk score of the initial state (with no IoT devices) is Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Results • The risk score of the initial state (with no IoT devices) is • FDMR problem - an increase of compared to initial state. In the random deployment the increase was . Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Results • The risk score of the initial state (with no IoT devices) is • FDMR problem - an increase of compared to initial state. In the random deployment the increase was . • MURD problem - on average, four to five devices can be deployed without any change in the risk score. When deploying four devices randomly the risk score is (increase of ). Remainder FDMR: Full Deployment with Minimal Risk. MURD: Maximal Utility without Risk Deterioration.
Additional Results • Trade-off between the allowed risk of the IoT deployment and the maximal number of IoT devices that can be deployed.
Conclusion • Planning the deployment of IoT devices is important. • Randomly deploying devices can greatly affect the security of the organization's network. • Novel method for suggesting the optimal deployment (in terms of the security risk) of a set of IoT devices within an organization.
Future Work • Develop heuristic functions for additional risk scores. • Add cyber-physical capabilities and unique functionalities to the IoT devices.
Discussion / Questions Thank You