Since many organizations are rapidly virtualizing servers and even desktops, there needs to be direction and guidance from top management in regards to information security. Organizations will need to develop a virtualization security policy that establishes the requirements for securely deploying, migrating, administering, and retiring virtual machines. In this way a proper information security framework can be followed in implementing a secure environment for hosts, virtual machines, and virtual management tools. This article is part two of a series on virtualization. The previous article was titled “Critical security considerations for server virtualization.”
As with other policies, the security policy should not specify technologies to be utilized. Rather, it should specify requirements and controls. Technologies will be implemented to satisfy the requirements and controls provided by the policy.
- Auditing and accountability
- Server role classification
- Network service
- Configuration management
- Host security
- Incident response
Auditing and accountability
The auditing and accountability portion has to do with the responsibilities of administrators, management, and users of the virtual environment. It is important to specify administrative roles such as backup operators, host administrators, virtual network administrators, server users, and self-service portal users. For smaller organizations, a few people may fill these roles but larger organizations will specify greater separation of duties between roles. Clearly identify the server role classifications that each user role is able to access.
Furthermore, this section should indicate that administrative actions will be logged and audited. Logs should be redundant, backed up regularly, and applications should be available for audit log searching and review.
Server role classification
Virtual machines or guests, serve different roles such as a file server, domain controller, email server, remote access server, or database. Some roles are more sensitive than others and thus they should be treated differently. Roles can be determined by the applications a server hosts or the data it hosts, as well as its criticality and value.
A series of classification levels such as standard, secure, and highly secure should be specified. The number of levels you have is determined by your organization’s business rules. For each classification, clearly state the server roles and information types that would fall into the category and the level of authentication, segmentation, encryption, and integrity verification necessary. For example, for segmentation, virtual machines classified as highly secure must be located on physically distinct hosts and separate logical networks and backup media should be allocated solely for use on highly secure systems.
The network service section details how remote access to hosts and virtual machines will be conducted or if it is allowed at all. It specifies Access Control List (ACL) requirements and how logical addresses will be allocated, distributed, and managed for virtual hosts and machines. Resource limits for hosts should be specified so that hosts are not overburdened with virtual machines causing performance degradation. Indicate the need for service accounts and least privilege configuration of service account privileges, ie: configuring service accounts with the bare minimum privileges necessary for the service to function.
The configuration management section is concerned with maintaining the consistency of the virtual environment. This section should specify the types of changes that require approval and how each type is approved. Any exemptions to the approval process are listed. Some change types include virtual network creation, modification, or removal, host addition or removal, host hardware modification, or virtual machine hardware modification.
Approval stages should be specified including the roles or groups responsible for approving change requests and the types of change requests that can be approved by each role or group. List how authorization will take place and where and how change authorizations are tracked and stored.
The configuration management section should also include statements on how violations of the configuration management policy will be dealt with and how actual changes are validated against logged changes. This includes any auditing that is required for change controls.
The host security section defines where hosts will be stored, how hosts are monitored, and how physical and remote access to the hosts is controlled. The location of hosts is important because hosts need to be available and secure. The location determines the level of network connectivity such as redundant network links and internet connectivity as well as power redundancy, power availability and cooling.
The next part of host security deals with how the hosts are monitored. Specify the types of monitoring that will take place. For example, physical monitoring may use closed circuit cameras that archive footage to DVD. You might specify logging of successful and failed logon attempts to the host servers and directory modification on storage devices containing virtual machine files or configuration data.
This section should detail what should happen if the virtual environment is compromised in some way. It should explain how information security incidents in the virtual environment are evaluated and how they are reported. It then defines the persons and groups responsible for controlling the issue and what constitutes issue resolution.
Your business may have an incident response plan in place already. This plan should be consulted when constructing this section so that it is aligned with the main information security policy. This section should still be included even if an incident response plan exists because the virtual environment can differ in how incidents are resolved and in what constitutes an incident.
Virtual environments differ greatly in Business Continuity (BC) methodologies. Since virtual machines are stored as files, they can be easily moved around. Business continuity methodologies, therefore take this into account in specifying how machines will be brought back into production when significant outages or disasters occur.
The business continuity section should specify what should be backed up and how it would be restored in the case of an emergency. Levels of emergency should be stipulated as well as the groups responsible for coordinating BC efforts. The section should also specify if resources such as a cold, warm, or hot site are necessary for BC.
The training section should clearly define what skills a person should have to fulfill the roles specified in the auditing and accountability section and how those skills will be taught and measured. It is important for those working on the environment to be trained in how to not only perform their job duties but to perform them in a secure manner.
The training section should specify ongoing assessment of training gaps and areas of focus for team members including how often training should occur, whether this will be handled internally or outsourced, and how training budgets will be determined. If training is to occur in house, curriculum evaluation and follow up reviews should be specified in the training portion. In this way, when technology changes, the team’s skills will be kept up to date as well.
The virtualization security policy contains many elements from other organizational security policies but it is specifically targeted to virtual hosts, the machines they contain, and the tools that manage them. It is important that virtual environments have such a policy because existing security controls do not adequately address the risks associated with using virtual machines. If you do not have a policy in place yet you are encouraged to develop one before your virtual environment is implemented. This policy will resolve security ambiguities associated with managing the environment and it will ensure a consistent approach to information security within your organization if those affected by the policy are properly trained and required to adhere to it.
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