Cloud Computing and Its Security Issues - A Review Jitender Grover 1 , Shikha 2 , Mohit Sharma 3 1, 2, 3 Department of Computer Science & Engineering, M. M. University, Sadopur, Ambala, India 1 jitendergrover0101@gmail.com , 2 shikha.vrgo@gmail.com , 3 mohitsharma2360@gmail.com Abstract : Cloud Computing is one of the popular techniques in distributed computing due to its ability to minimize the cost of computing when scalability and flexibility of computer process get increased. Cloud Computing provides shared resources and services via internet. Services are delivered through data center. Cloud Computing allows an interesting business proposal for IT industries to provide IT services without any extra investment. Client is able to perform heavy computer processes with low capable device (like mobile) which has resource to run the web browser. But cloud computing is crowded with many security related issues. When client saves his data to the company’s cloud, there may be chance of data breaching. So the purpose of this paper is to search out various issues in cloud computing where all computing is done on the server side and both data & tasks are stored on the data centers. Keywords- Cloud Computing, IaaS, PaaS, SaaS, Types of clouds, DDOS. I. INTRODUCTION In last few years, internet becomes an important part of life. So the need of internet as well as computing is increasing very rapidly which leads to the increase in cost of hardware, software and power consumption.[1] So the new technique known as cloud computing is a beam of hope to solve these problems by giving service over the internet and cutting down the cost of hardware and software. Services offered in cloud computing has various features like high scalability, reliability, flexibility and dynamic property. User needs to increase the resources in cloud system to improve the performance of his task. Cloud computing is internet (network) based distributed computing which emerged from grid computing. [2] It is used to provide application as services over the internet (network) and hardware by using virtualization of data center or data server, where responsibility of service availability is of provider. Data center is the collection of servers where all the applications used by user are collected. For example, everyone has an email id in which a user needs only an internet connection to access it. Cloud computing working is very much similar to an email client. All the data of a mail can be accessed anytime and anywhere if a user has an internet connection because data is not stored on a local computer system. [3] Clients need not to worry about the maintenance and management of the resources. On the basis of this property, cloud computing is also known as utility computing or IT on demand [4]. But cloud computing has much issues about security, because all information of client is stored on server. If cloud provider wants to misuse the client information, it can do so and that means cloud is not fully safe for sharing due to the chances of information leak or theft. So this paper picks some emerging issues in respect of security, privacy and its challenges. II. CLOUD COMPUTING: ITS TYPES & SERVICES The cloud computing takes place when numerous computers are using services which are distributed over the network (internet) and connected to the data center (private/public). Every service is loosely attached. If one service gets failed then it will not affect the other services. Cloud computing is performed in two phase as frontend and back end. The front end is a client who gets served by those services which are provided by the back end which is the cloud system. [8] Fig 1: Cloud Computing Model Definition of cloud computing according to The National Institute of Standards and Technology (NIST) is: “Cloud computing is a way of enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) IEEE - 33044 5th ICCCNT - 2014 July 11 - 13, 2014, Hefei, China