## 5 Security Issues and Cyber Attacks in Wireless Sensor Networks  
The wireless sensor networks used for smart grid applications have different characteristics than communication networks used for other generic applications. These characteristics are in terms of deployment topology, data processing, environmental conditions and network throughput. The security issues are related to confidentiality, authentication, availability, integrity, authorization and newness. Confidentiality deals with secrecy of data communication. Authentication is necessary for prevention of fake messages from malicious sensor nodes. It ensures data authenticity. Availability means consistency in services in presence of attacks. Integrity means the data or messages are received in an unaffected form at the destination. Authorization means only authorized sensor nodes can communicate and unauthorized access of data must be prevented. Newness of data is inevitable to ensure that attackers do not replay the old data again to hinder the security of WSN [65; 66; 67]. It is very challenging to ensure the stated measures of data authenticity and security in WSN due to following constraints mentioned in Figure 3.  
* Device Constraints: WSN nodes have very limited storage, processing and computational capabilities. They have limited power as they are battery operated.
* Deployment Constraints: Sensor nodes are deployed in potentially unsecured environments. They are deployed either in fixed manner or in random manner. They are remotely managed and controlled [66; 67; 68; 69].
* Communication Constraints: WSNs communicate using radio transmissions and most of them use unlicensed ISM band which is used for many other applications. Co-existence of various wireless standards is a major challenge for secured communication.  
Due to above reasons, sensor nodes are prone to eavesdropping or jamming attacks. Moreover, limited processing and storage capabilities of sensor nodes prevent the use of advanced cryptographic methods. Public key cryptography requires expensive computational techniques. Limited batteries of WSN make them prone to denial of service attacks which can further drain the energy from sensor nodes. Tampering of sensor nodes and reprogramming of chip are the possible attacks. The security of WSN can be endangered by reverse engineering [65; 66; 67; 68]. Smart grid also employs various devices and communication protocols at different network levels. Thus, WSN interoperability and security with other devices is also a matter of concern. The protection and privacy of WSN must be treated carefully for smart grid applications which is a broad network comprising of enormous networks and protocols. The public and private security measures for WSN in various smart grid applications require costly solutions [67; 68; 69]. The cost-security tradeoff must  
Figure 3: Major WSN constraints.  
be carefully implemented. Figure 4 shows the complete overview of applications, security issues and objectives of WSN for smart grid network.  
In addition to above wireless network security issues, WSNs are vulnerable to cyber-attacks on various network layers [70]. Figure 5 depicts the classification of various cyber-attacks in WSN.