# Vulnerability Assessment of Sensor Systems
###### Abstract  
There are more and more applications of sensors in today's world. Moreover, sensor systems are getting more complex and they are used for many high-risk security-critical purposes. Security assurance is a key issue for sensors and for other information technology (IT) products. Still, sensor security facilities and methodologies are relatively poor compared to other IT products. That is why a methodical approach to the sensor IT security is needed, i.e., risk management, implementation of countermeasures, vulnerability removal, and security evaluation and certification. The author proposes to apply the main security assurance methodology specified in ISO/IEC 15408 Common Criteria to solve specific security problems of sensors. A new Common Criteria compliant method is developed which specifies the vulnerability assessment process and related data in a structured way. The input/output data of the introduced elementary evaluation processes are modeled as ontology classes to work out knowledge bases. The validation shows that sensor-specific knowledge can be acquired during the vulnerability assessment process and then placed in knowledge bases and used. The method can be applied in different IT products, especially those with few certifications, such as sensors. The presented methodology will be implemented in a software tool in the future. intelligent sensor; IT security evaluation; security assurance; Common Criteria; vulnerability assessment [corref]organization=aff1,aff2,aff3  
transport-, energy-, and security monitoring systems, etc. Any breach of sensor behaviour may impact any object in its environment. * Sensor resources (computation, memory, power) and security facilities are relatively poor compared to other IT systems, but the risk is similar. Some threats are sensor-specific and some are the same as those of IT systems. * Using sensor vulnerabilities and other weaknesses, an intruder may get access to the entire system. Sensors cannot be the weakest links of complex systems. The issue is how to enhance the security of sensors recognized as specific IT products. A possible way is to adapt known, proven methods to this specific domain. The question is which methods can be used or adapted and what the range of this adaptation could be. Generally, sensors are used in many high-risk security-critical environments where valuable assets exist and/or important services are provided. The risk is mitigated by countermeasures, which stand up against threats, or by removing vulnerabilities. The question is whether the countermeasure will act properly when the threat occurs and really will mitigate the risk in this critical situation. Basically, not all countermeasures can be applied, only the effective ones that guarantee security assurance. The assurance of an IT product means that the product meets its security objectives, i.e., the product-implemented security measures will be able to counter threats when they occur. The IT security assurance concepts and relationships between them are presented in the international standard [1]. Different technical mechanisms or methods applied to the IT systems can raise their assurance. With respect to sensors, examples of such mechanisms can be: a dedicated routing protocol for wireless sensor networks, as discussed in two papers [2; 3], or reliable and fault-tolerant initial data storage, as presented in another paper [4]. Assurance can further grow when such mechanisms are well implemented, thoroughly analyzed, and tested by independent teams according to the defined schemas and methods. These activities are supported by the basic security assurance methodology, which is specified in the ISO/IEC 15408 Common Criteria (CC) standard [5]. This methodology provides confidence that countermeasures applied in the IT product (hardware, firmware, software, system) are relevant, sufficient, and correct, and will minimize risk in the operational environment. This is the foundation of the customers' confidence in the IT product.