# Secure Cloud Infrastructure: A Survey on Issues, Current Solutions, and Open Challenges
## 4 Security Issues in Cloud Computing Infrastructure  
Four main levels should be considered when planning for and applying security in cloud infrastructure, which are data level, application level, network level, and the host level [31]. These levels are shown in Figure 6.  
According to [31], these levels are described as in the following paragraphs. Security at the data level refers to providing protection for data at rest and in transit to protect the data from loss or leakage, which significantly impact data security and privacy. Malicious actors could compromise the data exchanged between the systems within the cloud, referred to as data in transit. Sniffing and man-in-the-middle (MITM) are the common attacks against data in transit within cloud ecosystem. In addition, several threats including, but not limited to, data leakage, hijacking, manipulation and eradication can affect the confidentiality, integrity, and availability of the data at rest. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Reference** & **Contribution** & **Data** & **Application** & **Host** & **Network** \\ \hline
[18] & The study reviewed the security issues regarding user & \(\surd\) & & & & \\  & data sensitivity on cloud architecture. & & & & & \\  & The study focused on identified cloud computing & & & & & \\
[19] & security issues during data migration to the cloud and & \(\surd\) & & & & \\  & presented solutions for resolving potential threats. & & & & & \\
[20] & The survey performed a taxonomy to compare key & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\) \\  & services that are regularly used by cloud applications. & & & & \\  & This study focused on the crypto cloud with various & & & & \\
[21] & Communication, Storage, and Service Level & & & & \\  & Agreements. & & & & \\
[22] & The survey focused on data privacy. & & & & \\  & The study highlighted the security requirements for & & & & \\  & cloud computing. & & & & \\
[24] & The study was classifying types of threats based on & & & & \\  & service resources in the context of the cloud. & & & & \\
[25] & The study reviewed DDoS techniques used in cloud & & & & \(\surd\) \\  & computing. & & & & \\  & The study evaluated major attacks targeting the & & & & \\  & security of Cloud Computing. & & & & \\  & The study reviewed technologies that allow for & & & & \\
[27] & privacy-aware outsourcing of storage and processing & & & & \\  & of sensitive data to public clouds. & & & & \\  & The study provided security issues and requirements & & & & \\
[17] & for the cloud, identified threats, and known & & \(\surd\) & \(\surd\) & & \(\surd\) \\  & vulnerabilities. & & & & \\
[30] & The study is more about the security from providers & & & & \\  & perspectives. & & & & \\  & Provides an extensive survey on issues that cloud & & & & \\  & computing infrastructure faced at its levels & & & & \\  & (Application, Host, and Network and data level). & & & & \\ This survey & & & & & \\  & presents some existing solutions used to mitigate & & & & \\  & these issues. & & & & \\  & Highlights some open challenges that still need to be & & & & \\  & solved. & & & & \\ \hline \end{tabular}
\end{table} 
Table 2: Summary of existing surveys. Application level: Security at this level refers to providing protection for applications when utilizing the hardware and software resources to prevent the attackers to get control over these applications. The most major threats at this level are denial of service (DoS) attacks that affect software applications. Network level: Security at this level refers to providing protection for the network when using a virtual firewall, demilitarized zone (DMZ), and data in transit. For this purpose, information about different types of firewalls should be monitored, collected, and maintained. Host level: Security at this level refers to providing security for the host when using a virtual server, hypervisor, and virtual machine. It is important to collect the information about the system log files to know when and where the applications have been logged.