You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Emphasis on Cloud Optimization and Security Gaps: A Literature Review 
Chapter Title:  Case study 
1. Abstract of Cited Paper (BIB001):  Cloud computing is an emerging technological paradigm that provides a flexible and scalable information technology infrastructure to enable business agility. There are different vulnerabilities in cloud computing and various threats to cloud computing. We have investigated several real-world cases where companies' cloud was infiltrated by attacks. In this paper several types of attacks are discussed, real-world cases are studied, and the solutions that providers developed are presented. Our current research will also be discussed. 
2. Abstract of Cited Paper (BIB002):  Cloud computing is a style of computing in which dynamically scalable and other virtualized resources are provided as a service over the Internet. The energy consumption and makespan associated with the resources allocated should be taken into account. This paper proposes an improved clonal selection algorithm based on time cost and energy consumption models in cloud computing environment. We have analyzed the performance of our approach using the CloudSim toolkit. The experimental results show that our approach has immense potential as it offers significant improvement in the aspects of response time and makespan, demonstrates high potential for the improvement in energy efficiency of the data center, and can effectively meet the service level agreement requested by the users. 
3. Abstract of Cited Paper (BIB003):  CSSICA is proposed to find the lowest service time for cloud composite services.PROCLUS is used to divide service providers into 3 categories based on service time.Selection probability of categories is calculated using their average service time.Utilizing achieved categories CSSICA has been able to make more conscious selections. Aiming to provide satisfying and value-added cloud composite services, suppliers put great effort into providing a large number of service providers. This goal, achieved by providing the "best" solutions, will not be guaranteed unless an efficient composite service composer is employed to choose an optimal set of required unique services (with respect to user-defined values for quality of service parameters) from the large number of provided services in the pool. Facing a wide service pool, user constraints, and a large number of required unique services in each request, the composer must solve an NP-hard problem. In this paper, CSSICA is proposed to make advances toward the lowest possible service time of composite service; in this approach, the PROCLUS classifier is used to divide cloud service providers into three categories based on total service time and assign a probability to each provider. An improved imperialist competitive algorithm is then employed to select more suitable service providers for the required unique services. Using a large real dataset, experimental and statistical studies are conducted to demonstrate that the use of clustering improved the results compared to other investigated approaches; thus, CSSICA should be considered by the composer as an efficient and scalable approach.

Literature Review:
The free cloud infrastructure availability may be misused for many malicious activities BIB001 . In cloud computing, the applications and data are relocated to the cloud, which paves the way for the hackers to scatter the data and information. Case 1. In Mat Honan's case, the entire digital life was destroyed within 1 hour. His Twitter account was used to publish hate, racist and homophobic messages. His personal data was deleted completely from iPhone, iPad, and MacBook. The Google account was also deleted. The attacker accessed the Honan's amazon's account using the public information and found the last four digit of his credit card. To access the Apple ID, they use this information; his Gmail account was used for password recovery. Due to lack of cooperation within the technology industry and data management policies, the dilemma occurs  . Case 2. In Sony's case, 24.6 million PC gamers are affected which gives a strong blow to the company and the Cloud entertainment concept as a whole. The private and sensitive data of gamers are hacked and used this data to access the Sony's PC Games Network. The attack against Sony's network was due to a hacker renting service of Amazon Elastic Compute Cloud. The level of trust in Sony's PC Games Network and the Cloud technology as a whole was negatively impacted by the security breach against Sony  . The vulnerability used in this attack is not yet revealed. Case 3. In Amazon's case, the hackers broke the Amazon's Cloud infrastructure by getting unauthorized access to Amazon's EC2 service by hacking a vulnerable website and secretly installing Zeus password-stealing botnet. However, the botnet on the cloud computing infrastructure was identified by the security researchers and removed  . The hacked companies did not disclose the vulnerability used by the hackers. The hackers may have obtained the administrative password by stealing and accessed the network. This has created some concerns because the Cloud Computing has been built on a resource sharing concept. Further, spammers have been using rented servers for their spam activities, and so a large portion of EC2 IP addresses was blacklisted  . Case 4. In Dropbox's case, the hackers obtained the passwords from other websites and used them for spamming and other illegal activities. The account information that is stored in the cloud is vulnerable. Dropbox users' logging credentials were hacked. Dropbox representatives acknowledged the breach and introduced new security measures to mitigate the problem. A. K o n a k, S. K o n a k and S n y d e r  Game theoretic genetic algorithm For reliable server assignment problem under attack A h m a d et al.  Hybrid genetic algorithm Workflow scheduling problem B a r a t i and S h a r i f i a n  Support vector regression Cloud load prediction K a r a m i and Z a p a t a [9] Radial basis function particle swarm optimization Mitigating Denial of service attacks. B a m a k a n et al.  Particle swarm optimization To improve the performance of MCLP classifier Shu, W. W a n g and Y. W a n g BIB003 Immune clonal optimization Green cloud computing P a c i n i, M a t e o s and G a r i n o  Ant colony optimization Balancing throughput and response time in online scientific clouds S u g u n a and S u h a s i n i  Enriched genetic algorithm For efficient disaster recovery in cloud environment P a l m i e r i et al.  Greedy randomized adaptive search procedure To tackle re-optimization problem J u l a, O t h m a n, and S u n d a r a r a j a n BIB004 Imperialist competitive algorithm A two-factor authentication, malicious activities' detection, and auditing features were introduced BIB002 . Various security measures have been implemented, but still looking for better secure systems.