## 2 Literature Review
### Smart Healthcare
#### 2.5.1 Cyber Threats or Attacks  
Smart health is an important field that continually analyzes patients' health, alternative treatments, and cutting-edge disease-fighting technology. The purpose of smart health is to provide individuals with medical services at any time and from any place. Smart health monitoring devices are often connected through wireless networks, which are vulnerable to  
Figure 5: Smart healthcare scenario over blockchain.  
cyber threats. However, various risks may endanger these health monitoring applications and systems [103; 104]. These include denial-of-service (DoS) attacks, fingerprint and timing-based eavesdropping, router attacks, select and forwarding attacks, sensor attacks, and replay attacks [105; 106]. In this paper [107], the authors investigate the consequences of these attacks on health monitoring systems and recommend some interventions based on their research findings.  
The most challenging aspect of smart health apps is protecting data from numerous assaults while using simple approaches and algorithms. Given the security problems associated with implementing smart health apps as the primary data collecting and transmission source, cyber threats are categorized to create a viable defense strategy. This research [5] contributes to the analysis of security and privacy in the context of smart cities for healthcare applications in two ways. On the one hand, an overview of several IoT applications and their cyber vulnerabilities is provided. On the other hand, a complete assessment of potential solutions to the issue of cyber assaults is given.  
In recent years, smart healthcare has gained popularity. Because of the data it collects, a more secure mechanism is required to maintain security and privacy. As a result, these techniques may also guarantee security and privacy in smart health. This review paper aims to assess individuals' concerns with security issues in their smart homes and to start a debate about how healthcare equipment that comes packaged with future houses is susceptible to cyber attacks that result in data breaches. Blockchain is proposed in this study [108] to increase security and privacy in smart healthcare. The proposed platform uses blockchain technology and considers the client's control over the healthcare data, implying the ability to share data with a specific association or person on a case-to-case and field basis. Using this platform, the writers discussed emerging blockchain technology and how its components may help healthcare flourish while maintaining total security.  
Humans benefit from the fast progress of the MIoT connected with biosensors in various ways, including smart healthcare systems (SHeSs). The combination of MIoT devices and the increasingly networked nature of the healthcare environment enables healthcare providers to provide more efficient and effective emergency and preventative medical services to their patients. SHeS offers several chances for healthcare professionals and institutions to monitor patients' health remotely. The health statistics acquired by SHeS are kind. However, SHeS exposes patients' health data to various assaults.