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Cloud Security Challenges

John W. Rittinghouse and James F. Ransome

Although virtualization and cloud computing can help companies accomplish more by breaking the physical bonds between an IT infrastructure and its users, heightened security threats must be overcome in order to benefit fully from this new computing paradigm. This is particularly true for the SaaS provider. Some security concerns are worth more discussion. For example, in the cloud, you lose control over assets in some respects, so your security model must be reassessed. Enterprise security is only as good as the least reliable partner, department, or vendor. Can you trust your data to your service provider? This excerpt discusses some issues you should consider before answering that question.

With the cloud model, you lose control over physical security. In a public cloud, you are sharing computing resources with other companies. In a shared pool outside the enterprise, you don't have any knowledge or control of where the resources run. Exposing your data in an environment shared with other companies could give the government "reasonable cause" to seize your assets because another company has violated the law. Simply because you share the environment in the cloud, may put your data at risk of seizure. Storage services provided by one cloud vendor may be incompatible with another vendor's services should you decide to move from one to the other. Vendors are known for creating what the hosting world calls "sticky services;" services that an end user may have difficulty transporting from one cloud vendor to another (e.g., Amazon's "Simple Storage Service" [S3] is incompatible with IBM's Blue Cloud, or Google, or Dell).

If information is encrypted while passing through the cloud, who controls the encryption/decryption keys? Is it the customer or the cloud vendor? Most customers probably want their data encrypted both ways across the Internet using SSL (Secure Sockets Layer protocol). They also most likely want their data encrypted while it is at rest in the cloud vendor's storage pool. Be sure that you, the customer, control the encryption/decryption keys, just as if the data were still resident on your own servers.

Data integrity means ensuring that data is identically maintained during any operation (such as transfer, storage, or retrieval). Put simply, data integrity is assurance that the data is consistent and correct. Ensuring the integrity of the data really means that it changes only in response to authorized transactions. This sounds good, but you must remember that a common standard to ensure data integrity does not yet exist.

Using SaaS offerings in the cloud means that there is much less need for software development. For example, using a web-based customer relationship management (CRM) offering eliminates the necessity to write code and "customize" a vendor's application. If you plan to use internally developed code in the cloud, it is even more important to have a formal secure software development life cycle (SDLC). The immature use of mashup technology (combinations of web services), which is fundamental to cloud applications, is inevitably going to cause unwitting security vulnerabilities in those applications. Your development tool of choice should have a security model embedded in it to guide developers during the development phase and restrict users only to their authorized data when the system is deployed into production.

As more and more mission-critical processes are moved to the cloud, SaaS suppliers will have to provide log data in a real-time, straightforward manner, probably for their administrators as well as their customers' personnel. Someone has to be responsible for monitoring for security and compliance, and unless the application and data are under the control of end users, they will not be able to. Will customers trust the cloud provider enough to push their mission-critical applications out to the cloud? Since the SaaS provider's logs are internal and not necessarily accessible externally or by clients or investigators, monitoring is difficult. Since access to logs is required for Payment Card Industry Data Security Standard (PCI DSS) compliance and may be requested by auditors and regulators, security managers need to make sure to negotiate access to the provider's logs as part of any service agreement.

Cloud applications undergo constant feature additions, and users must keep up to date with application improvements to be sure they are protected. The speed at which applications will change in the cloud will affect both the SDLC and security. For example, Microsoft's SDLC assumes that mission-critical software will have a three- to five-year period in which it will not change substantially, but the cloud may require a change in the application every few weeks. Even worse, a secure SLDC will not be able to provide a security cycle that keeps up with changes that occur so quickly. This means that users must constantly upgrade, because an older version may not function, or protect the data.

Having proper fail-over technology is a component of securing the cloud that is often overlooked. The company can survive if a non-mission-critical application goes offline, but this may not be true for mission-critical applications. Core business practices provide competitive differentiation. Security needs to move to the data level, so that enterprises can be sure their data is protected wherever it goes. Sensitive data is the domain of the enterprise, not the cloud computing provider. One of the key challenges in cloud computing is data-level security.

Most compliance standards do not envision compliance in a world of cloud computing. There is a huge body of standards that apply for IT security and compliance, governing most business interactions that will, over time, have to be translated to the cloud. SaaS makes the process of compliance more complicated, since it may be difficult for a customer to discern where its data resides on a network controlled by its SaaS provider, or a partner of that provider, which raises all sorts of compliance issues of data privacy, segregation, and security. Many compliance regulations require that data not be intermixed with other data, such as on shared servers or databases. Some countries have strict limits on what data about its citizens can be stored and for how long, and some banking regulators require that customers' financial data remain in their home country.

Compliance with government regulations such as the Sarbanes-Oxley Act (SOX), the Gramm-Leach-Bliley Act (GLBA), and the Health Insurance Portability and Accountability Act (HIPAA), and industry standards such as the PCI DSS, will be much more challenging in the SaaS environment. There is a perception that cloud computing removes data compliance responsibility; however, it should be emphasized that the data owner is still fully responsible for compliance. Those who adopt cloud computing must remember that it is the responsibility of the data owner, not the service provider, to secure valuable data.

Government policy will need to change in response to both the opportunity and the threats that cloud computing brings. This will likely focus on the off-shoring of personal data and protection of privacy, whether it is data being controlled by a third party or off-shored to another country. There will be a corresponding drop in security as the traditional controls such as VLANs (virtual local-area networks) and firewalls prove less effective during the transition to a virtualized environment. Security managers will need to pay particular attention to systems that contain critical data such as corporate financial information or source code during the transition to server virtualization in production environments.

Outsourcing means losing significant control over data, and while this isn't a good idea from a security perspective, the business ease and financial savings will continue to increase the usage of these services. Security managers will need to work with their company's legal staff to ensure that appropriate contract terms are in place to protect corporate data and provide for acceptable service-level agreements.

Cloud-based services will result in many mobile IT users accessing business data and services without traversing the corporate network. This will increase the need for enterprises to place security controls between mobile users and cloud-based services. Placing large amounts of sensitive data in a globally accessible cloud leaves organizations open to large distributed threats-attackers no longer have to come onto the premises to steal data, and they can find it all in the one "virtual" location.

Virtualization efficiencies in the cloud require virtual machines from multiple organizations to be co-located on the same physical resources. Although traditional data center security still applies in the cloud environment, physical segregation and hardware-based security cannot protect against attacks between virtual machines on the same server. Administrative access is through the Internet rather than the controlled and restricted direct or on-premises connection that is adhered to in the traditional data center model. This increases risk and exposure and will require stringent monitoring for changes in system control and access control restriction.

The dynamic and fluid nature of virtual machines will make it difficult to maintain the consistency of security and ensure that records can be audited. The ease of cloning and distribution between physical servers could result in the propagation of configuration errors and other vulnerabilities. Proving the security state of a system and identifying the location of an insecure virtual machine will be challenging. Regardless of the location of the virtual machine within the virtual environment, the intrusion detection and prevention systems will need to be able to detect malicious activity at virtual machine level. The co-location of multiple virtual machines increases the attack surface and risk of virtual machine-to-virtual machine compromise.

Localized virtual machines and physical servers use the same operating systems as well as enterprise and web applications in a cloud server environment, increasing the threat of an attacker or malware exploiting vulnerabilities in these systems and applications remotely. Virtual machines are vulnerable as they move between the private cloud and the public cloud. A fully or partially shared cloud environment is expected to have a greater attack surface and therefore can be considered to be at greater risk than a dedicated resources environment.

Operating system and application files are on a shared physical infrastructure in a virtualized cloud environment and require system, file, and activity monitoring to provide confidence and auditable proof to enterprise customers that their resources have not been compromised or tampered with. In the cloud computing environment, the enterprise subscribes to cloud computing resources, and the responsibility for patching is the subscriber's rather than the cloud computing vendor's. The need for patch maintenance vigilance is imperative. Lack of due diligence in this regard could rapidly make the task unmanageable or impossible, leaving you with "virtual patching" as the only alternative.

Enterprises are often required to prove that their security compliance is in accord with regulations, standards, and auditing practices, regardless of the location of the systems at which the data resides. Data is fluid in cloud computing and may reside in on-premises physical servers, on-premises virtual machines, or off-premises virtual machines running on cloud computing resources, and this will require some rethinking on the part of auditors and practitioners alike.

In the rush to take advantage of the benefits of cloud computing, not least of which is significant cost savings, many corporations are likely rushing into cloud computing without a serious consideration of the security implications. To establish zones of trust in the cloud, the virtual machines must be self-defending, effectively moving the perimeter to the virtual machine itself. Enterprise perimeter security (i.e., firewalls, demilitarized zones [DMZs], network segmentation, intrusion detection and prevention systems [IDS/IPS], monitoring tools, and the associated security policies) only controls the data that resides and transits behind the perimeter. In the cloud computing world, the cloud computing provider is in charge of customer data security and privacy.

Related Reading

Cloud Computing with Software as a Service (SaaS)

The Evolution of Managed Security Services

Cloud Security Alliance Issues Version Two of Guidance for Critical Areas of Focus in Cloud Computing

Securing SaaS Applications

About the Author

Cloud Computing: Implementation, Management, and Security From Cloud Computing: Implementation, Management, and Security by John W. Rittinghouse and James F. Ransome. New York: Auerbach Publications, 2009.
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