3.2.4. Alteration Attack

An alteration attack happens when the HAN, an appliance, or the SM is compromised and an adversary maliciously alters the consumption report or forges a message. The forged message or consumption report can lead to false execution, for example, if a message is sent to set the oven to 120 °C but when altered sets the water heating system to 120 °C then it might lead to injuring a person at home or can also lead to system failure or short circuit. Even if a consumption report is forged, it may cause the customer to pay for electricity that he has not consumed [56].

### 3.2.5. Message Modification Attack

Communication is a key way in which the SG differs from a traditional grid. If there is an adversary between SG and HAN, it can modify the messages sent to or received from the SG/HAN, which may result in a trust deficit between the working entities and thus leading to serious damage at either side [23].

### 3.2.6. Energy Import/Export Attack

The SG allows for distributed power generation, where a consumer can install the renewable power generation resources at the consumer's premises. It feeds the surpass energy into the national grid and can also demand extra energy resources from the grid when needed [23]. For example, an adversary demands the energy import from the grid, which is not needed, and exports the energy from home to the grid even when it is needed at home [56]. Similarly, if a plug-in electrical vehicle is charged and imports unnecessary energy from the grid, which is not needed at peak hours, it can lead to power shortfalls and load shedding.

### **4. Advanced Privacy Preserving Scheme and Its Countermeasures**

In this section, we study the latest privacy preserving schemes related to user authentication, data aggregation, key management, and CIA triad.

In [32], the authors have reviewed security issues related to smart homes. The purpose is to portray the scenarios that pose a threat to smart homes, which are an essential part of the smart grid. The smart grid security objectives adopted in this paper are confidentiality, integrity, availability, authenticity, authorization, and nonrepudiation attacks. Furthermore, in [32], the authors examine potential cyber and physical security threats in terms of security objectives.

The communication infrastructure of the smart grid, while considering reliability and challenges to security in the smart grid, is provided in [57]. In [58], an emerging technology, i.e., software defined network (SDN), is discussed. A complete overview of the HEMS literature with reference to main principles, setups, and enabling technologies is offered in [59]. The scheme in [60] comprises existing architectures, applications, and prototypes of IoT-assisted SG systems, and provides an overview of IoT-assisted SG systems.

In the studied literature, the following points have been observed:

• The security challenges of the smart grid are discussed and threats are evaluated.


In [61], big data collection and managemen<sup>t</sup> is surveyed. The authors have used an analytical method to study big data and its applications associated with smart grids. The paper gives an insight about the sources of big data in smart grids and real-time processing to predict a pattern for decision making. In [62], a detailed survey on the future wireless communications systems is performed. The authors have reviewed the energy utilization, redistribution, and trading. The authors have performed a comprehensive study of the current literature and have observed the concern about security vulnerabilities of smart grids. In [63], with the use of new IoT technologies, an overview of smart grid security improvements and weaknesses is provided.
