Public Cloud Computing vs. Private Cloud Computing: How Security ...

Public Cloud Computing vs. Private Cloud Computing: How Security Matters


Research Paper

Public Cloud Computing vs. Private Cloud Computing: How Security Matters Delvis Simmonds Alli Wahab Cameron University

IT Capstone Dr. Diaz Gomez April 27, 2012

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Table of Contents Abstract ......................................................................................................................3 Introduction……………………………………………………………………………………………………………….3 The growth of Cloud Computing ..................................................................................5 Public Cloud Security Issues ................................................................................................................................7

Private Cloud Computing ............................................................................................9 Private Cloud Security Issues ..............................................................................................................................9

Concise comparison .................................................................................................. 10 Conclusions & Future Work ....................................................................................... 11 Bibliography ............................................................................................................. 12


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Public Cloud Computing vs. Private Cloud Computing: How Security Matters Delvis Simmonds, Alli Wahab Computing and Technology Department, Cameron University, Lawton, OK, USA

Abstract Cloud computing has promised to enhance efficiency, flexibility, greater agility, less capital expenditure and to overcome geographic limitations to compete in a global market. If adopted and implemented, businesses would require not only new architectures, but also new ways to procure IT services. More and more companies are shifting to Cloud based services, but at the same time they are concerned about the security risks. One thing that is really unclear to many is the understanding of what a Cloud really is. Hopefully after the definitions and illustrations of Cloud computing are given you will understand it better. Much attention will be given to public and private Cloud computing issues; as more businesses today utilize Cloud services and architectures, more threats and concerns arise.

Introduction Cloud computing represents a major change in how we store digital information and run computer applications hosted in the “Cloud” (Miller, 2009). While still a buzzword, the Cloud seems to be confusing, and the concept tends to evoke multiple responses (Vorro, 2011). There are many definitions of Cloud computing, but they all focus on certain characteristics of it. The several definitions stem from the three main categories of Cloud computing which are Infrastructure-as-a-Service (IaaS), Platform-asa-Service (PaaS), and Software-as-a-Service (SaaS). Furthermore, Cloud security is also a broad term and is of major concern. The security challenges Cloud computing presents are formidable, including those faced by public Cloud whose infrastructure and computational resources are owned and operated by an outside party that delivers services to the general public via a multitenant platform and for the private Cloud which is hosted on-premise, scales “only” into the hundreds or perhaps thousands of nodes, connected primarily to the using organization through private network links. Security concerns such as secure data transfer, secure software interfaces, secure stored data, user access control and data separation must be considered before moving to the Cloud (Beckham, 2011). Attempting to address security and privacy issues after implementation and deployment is not only much more difficult and expensive, but also exposes the organization to unnecessary risk (Julie, 2011). As a result, many companies remain skeptical about entrusting their data and computing tasks to outside vendors including Microsoft, IBM Smart Cloud, and Google. Every trade publication and analyst firm has done a survey of CIOs regarding Cloud adoption. Results showed that security was the top reason why CIOs are not too anxious about adapting to the Cloud (see Figure 1).


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Figure 1: The results in the graph above are gathered from a survey of CIOs, organizations and IT professionals, which was carried out by the International Data Corporation (IDC) in 2009. On a whole, the results have been quite steady up until now. The highest challenge/issue related to the Cloud is security. Security is not the only concern. Issues such as cost, availability, performance, and standardization are also very high considerations. This research paper will provide a definition of Cloud computing, the security issues related to public and private Cloud computing, and give a concise comparison of both models, focusing more on the security issues.

Definition of Cloud computing The term Cloud computing entails many different notions. You will find that some definitions have more meaning than others; Gartner defines Cloud computing as being scalable, delivering IT-enabled services using the Internet (Gartner, 2012). On the other hand, The 451 Group sees Cloud computing as a set of business models and technologies that enables IT functions to be delivered and consumed via a third party. (Rhoton, J. 2011). Furthermore, Forrester defines Cloud computing as complex infrastructure that hosts end-customer applications and billed by consumption (Rhoton, J. 2011). The definition mostly used today is the one expressed by the National Institute of Standards and Technology (NIST), which states: “a model for enabling convenient, ondemand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction” (Grance, T., Mell, P., 2009). The NIST’s definition is much more detailed, and will be the one referenced to in this paper. Cloud computing is available in several service models. Each model has different levels of responsibility for security management. See Figure 2 below for a depiction of these service models.


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Figure 2: Cloud computing models. Taken from (Buecker, Lodewijkx, Moss, Skapinetz, Waidner, 2009). Figure 2 above shows that Software as a Service (SaaS) provides a number of ways to control access to the Web portal, such as the management of user identities, application level configuration, and the ability to restrict access to specific IP address ranges or geographies. Platform as a Service (PaaS) allow clients to assume more responsibilities for managing the configuration and security for the middleware, database software, and application runtime environments. Infrastructure as a Service (IaaS) model transfers even more control, and responsibility for security, from the Cloud provider to the client; access is available to the operating system that supports virtual images, networking, and storage. (Buecker, Lodewijkx, Moss, Skapinetz, Waidner, 2009).

The growth of Cloud Computing Over the past two years, the number of Cloud-based services implemented in businesses has increased, according to a survey carried out in 2011 by Ernst and Young, a


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global leader in assurance, tax, transaction and advisory services (see Figure 2).

Figure 2: A global information security survey of organizations carried out in 2011 by Ernst and Young revealed a 13% growth in the number of organizations using Cloudbased services from 2010 to 2011. However, in 2011 there was a 16% negative growth for plans on using Cloud-based services (Ernst and Young, 2011).

Previous Work The interesting debate of public Clouds vs. private Clouds has resulted in other research. In an article by Beth Schultz entitled “Public Cloud vs. private Cloud” 76% of IT-decision-makers would focus initially on the private Cloud, but private Clouds may not always be the best solution. The better approach is to evaluate specific applications, security and compliance considerations and then decide what is more appropriate for a private Cloud and what is more appropriate for a public Cloud. The size and type of the company are huge factors in the decision making process; if you are at a smaller company and don’t have a huge data center, then a public Cloud service will be acceptable. Whereas, if you are at a larger company which requires mission-critical applications or data, then it would not be wise to place the more important stuff on a public Cloud (Schultz, B. 2011). Microsoft TechNet has done some research and documentation on the security issues in public and private Clouds, reminding us not to ignore security, even when the CSP appears to control the entire stack (Microsoft TechNet (1), 2012). Whether the choice is a private Cloud or public Cloud the security of your data will be very important in both cases. Cloud computing is only as secure and reliable as the Cloud vendor providing the service, whether it is you or a third-party (Joyent, 2012).

Public Cloud Computing There are three Cloud models which companies can choose from, which are public Cloud computing, private Cloud computing and hybrid Cloud computing. Public Cloud computing means relying on third parties to offer efficient IT services over the


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Internet as needed. On the other hand, Private Cloud computing reassures the organization that their information and processes are more secure since everything is managed internally. Hybrid Cloud computing is a combination of both private and public services. Hybrid Cloud computing is another extensive topic; therefore this paper will not discuss it. The National Institute of Standards and Technology defines a public Cloud as a Cloud infrastructure that is made available to the general public or a large industry group. Public Clouds are owned by the organization(s) selling Cloud services (Grance, T., Mell, P., 2009). Figure 3 below gives a basic illustration of an organization using a public Cloud.

Figure 3: Illustration of an organization using public Cloud services. (Diagram by Delvis Simmonds and Alli Wahab, 2012).

Public Cloud Security Issues Cloud infrastructures are just another computer network. This means that Clouds will have the same security any network infrastructure will have (intrusion detection/ prevention etc.). It is up to the Cloud vendor (whether it be you or a third party) to determine the level of security required (Joyent, 2012). The International Organization for Standardization (ISO) provides some codes of practice for information security management, namely the ISO 27001 and 27002. The ISO 27001 covers all types of organizations. This document specifies the requirements for implementing security controls customized to the needs of the organization (ISO (1), 2008). The ISO 27002 is also customized to the needs of the organization, but it is intended to help meet requirements identified by a security risk assessment (ISO (2), 2008). There is an ongoing debate between IT professionals of whether or not private Clouds are really more secure. According to some analysts and vendors, there’s been no shortage of debate and consternation about the security threats public Cloud computing poses. The concern can be understandable; especially if sensitive data and vital applications are in the hands of a party not directly under your preview (Joe, 2011). Besides from the common view that private Clouds should be more secure, there are


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some interesting attributes/properties of public Clouds to consider. Public Clouds are hardened through continual hacking attempts. The NIST definition of public Clouds states that they are made available to the general public or a large industry group. Therefore, public Cloud providers are much larger targets for hackers than private Clouds. Public Clouds also attract the best security people available; the biggest and best Cloud service providers have millions of customers relying on them. They definitely would be meticulous about who they hire. Also public Cloud providers, especially larger companies like Google, Amazon, and Facebook would get the latest security gear much easier than a small to midsize private company. Here are some other security issues related to Public Cloud Computing: 

Assessment of the CSP Any small, young business can advertise Cloud-based services to the world. How are you sure that that company is capable and safe to work with? CSPs should hold industry certifications such as the SAS 70 Type II, which is an audit that provides independent 3rd party verification that a service organization’s policies and procedures are correctly designed (SAS 70, 2012).

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Security of the communication channels Data and communication protection is paramount in Cloud computing. We use the services provided even though the security mechanisms for secure communication is abstract. Services can be accessed several ways, such as through a thin client, laptop or mobile phone. The fact that your data is easily accessible through these channels, data is transferred across multiple networks, more especially if your CSP is extremely far away from your location. All communication should be protected using encryption and key management.

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Transparency of security processes - Some Cloud Service Providers may not explain their security processes for their own security reasons. Compliance with Regulations o Payment Card Industry Data Security Standard (PCI DSS) o Health Insurance Portability and Accountability Act (HIPAA) o Sarbanes-Oxley Act (SOA) o Proper implementation of the CIA triad (Confidentiality, Integrity, Assurance) o Geographical borders - The location of the customer’s data is significant. Public Cloud service providers typically implement robust data replication mechanisms as a safe guard for server failures. This means that the customer’s data might be distributed across the globe in various geographies. This would conflict with the customer’s need/requirements to keep their data within a specified border (Microsoft Corporation, 2011).

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Potentials of a single security breach - A single security breach not only destroys the CPS’s reputation but put


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your data and many others’ in danger. A perfect example is Sony’s data breaches in 2011. Sony faced customer relation fallouts, and lawsuits over its failure (Schwartz. M, 2011). 

Access control mechanisms

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Data Loss Cross-tenant data leakage - vulnerabilities of shared network infrastructure components, such as vulnerabilities in a DNS server, Dynamic Host Configuration Protocol, and IP protocol vulnerabilities, might enable network-based cross-tenant attacks in an IaaS infrastructure (Pfleeger, Irvine, Kwon, 2012).

Private Cloud Computing According to the National Institute of Standards and Technology (NIST) a private Cloud is a Cloud infrastructure that is operated solely for an organization. The organization or a third party can manage it. Private Clouds can exist on-site or off-site (Grance, T., Mell, P., 2009). Typically private Clouds are used when sensitive data is involved. Figure 2 below gives a basic illustration of an organization using a private Cloud.

Figure 2: Illustration of an organization with a private Cloud. (Diagram by Delvis Simmonds and Alli Wahab, 2012).

Private Cloud Security Issues Private Clouds have the same security concerns as public Clouds do, but typically on a smaller scale since private Clouds are operated solely for an organization. However, there are some specific concerns towards this Cloud model: • Security Architecture

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o Perimeter Security and insider attacks - Very often, traditional perimeter security is not configured to protect resources from attacks that come from within the organization (Microsoft (2), 2012). o Hypervisor vulnerabilities and network level authentication (IPSec, IPS/IDS) - Virtual machines are heavily used in Private Clouds. It is possible that those virtual machines will be able to have virtual communication with other virtual machines. Virtual machines should only be communicating with the ones they need to. Encryption and authentication mechanisms should be implemented using IPSec and/or IPS/IDS (Microsoft (2), 2012). •

Security Zones - Resources of different types and sensitivity levels should be located in separate security zones (Stawowski, M., 2007).

Based on previous studies and the definition of a private Cloud, private Clouds will immediately seem to be more secure than public Clouds because of how the infrastructure is designed. It gives the organization more control over their policies and security. According to NIST, the internal private Cloud is more suitable deployment models that offer an organization greater oversight and authority over security and privacy, and better limit the types of tenants that share platform resources, reducing exposure in the event of a failure or configuration error in a control. Private Clouds typically would suffer from perimeter complacency; thinking that because it is on the internal network, it must be secure; the Internet and viruses are still present. So, caution and security standards should not be lowered just because it is private (Bloomberg, 2012). Moreover, the private Cloud requires that to have total control over all layers of the stack, which includes any traditional network perimeter security you might want to have in place. In a private Cloud model, the Cloud services are not typically exposed to the general Internet users and remote access to private Cloud hosted resources is enabled through mechanisms used in traditional data centers. Private Cloud computing typically uses virtualization technologies to increase hardware utilization and to abstract compute, memory, network, and storage component from Private Cloud consumers (Thomas, 2011). See Table 1 below for a concise comparison of public Clouds and private Clouds.

Concise comparison Table 1: A concise comparison of public and private Clouds. Public Cloud Private Cloud Low investment hurdle High investment hurdle Negative loss and control over data IT organization retains control over data Higher risk of multi-tenancy data transfer Fewer security concerns


Conclusions & Future Work In this paper we have provided a definition of Cloud computing and highlighted the security issues/concerns related to public Clouds and private Clouds. As more businesses today utilize Cloud services and architectures, more threats and concerns arise. The attributes of both Cloud models shown in pages 7 to 10 and Table 1 definitely would make one contemplate the direction to take. Nevertheless, the integration of Cloud-based services in businesses is continuing. Both public and private Cloud models have their own advantages and challenges; therefore security will always be an issue. The needs and goals of each organization will vary. Therefore evaluating specific applications, security and compliance considerations would help in deciding what is more appropriate for a private Cloud and what is more appropriate for a public Cloud. Cloud computing is a very wide subject area. Even though the scope was scaled down to the security issues in public Cloud computing and private Cloud computing it was still quite a challenge getting details on certain areas; most information found during the research is related to either public Cloud computing or Cloud computing in general. The reason for this is that the term “Private Cloud” is not as widely accepted as Cloud computing. Research in the future about Cloud computing will most likely be on Hybrid Cloud Computing (the combination of services from public and private Clouds). Several recent Cloud surveys confirm these high levels of interest in hybrid Cloud. A Unisys survey in January 2011 indicated that 21% of IT organizations are focusing on hybrid Clouds, and a Sand Hill Group survey of over 500 IT managers indicates that hybrid Cloud use will triple over the next three years (Bitpipe, 2012).


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