The term "common control framework NIST" typically refers to the National Institute of Standards and Technology's (NIST) approach to designating "common controls" within its broader Risk Management Framework (RMF).
This practice allows an organization to implement a single security control once, and then share or "inherit" it across multiple information systems, thereby increasing efficiency and reducing compliance costs. The central document for this process is NIST Special Publication (SP) 800-53, Security and Privacy Controls for Information Systems and Organizations, which provides a comprehensive catalog of controls.
NIST's common controls: A strategic approach to efficiency and risk management
The common control strategy is a core component of the NIST Risk Management Framework (RMF), which is a comprehensive, six- or seven-step process for managing security and privacy risks. This approach is designed to streamline security compliance, especially in complex IT environments with many different systems that have overlapping security needs. Instead of each system being independently secured for identical risks, common controls allow for a centralized, "do once, use many times" approach.
The foundation: The NIST Risk Management Framework (RMF)
Before implementing common controls, an organization follows the RMF process. This sets the stage for a strategic and risk-based security program.
- Prepare: An organization establishes its risk management strategy and determines the necessary resources and risk tolerance.
- Categorize: Information systems and the data they process are categorized based on their potential impact to the organization if confidentiality, integrity, or availability were compromised. This categorization (low, moderate, or high) is a crucial step that determines the baseline of controls needed.
- Select: The organization selects a baseline set of security controls from the NIST SP 800-53 catalog based on the system's impact level. It is at this stage that the organization identifies which of these controls can be designated as "common".
- Implement: The selected controls are implemented on the systems.
- Assess: A security assessment determines if the controls are operating correctly.
- Authorize: A senior organizational official authorizes the system to operate based on the level of risk determined during the assessment.
- Monitor: The system is continuously monitored for new threats and vulnerabilities to ensure controls remain effective.
Common, hybrid, and system-specific controls
Within the RMF, security controls are designated into three distinct types to clarify responsibility and maximize efficiency.
- Common Controls: These are security controls that are inherited by multiple information systems. They are implemented once by a central authority, saving individual system owners from having to implement and manage them separately.
- Example: A standard physical security policy for all data center access. Rather than each system documenting and implementing its own physical access procedure, the data center operator implements the single, common control that all systems inherit.
- System-Specific Controls: These are controls implemented directly by a system and are only relevant to that system. They address risks unique to that particular system and cannot be inherited by others.
- Example: A unique database encryption requirement for a system that stores highly sensitive data.
- Hybrid Controls: These controls have a common and a system-specific component. The base control is common and provided by a central service, but certain aspects are configured locally by the system owner.
- Example: An organization's common policy for user training (AT-2) is centrally managed, but each system owner is responsible for documenting and ensuring their specific users have completed it.
Tailoring and overlays: Customizing the framework
While NIST provides standard baselines, it explicitly encourages organizations to customize them to fit their specific operational needs and risk tolerance. This process, called "tailoring," ensures that controls are not arbitrarily applied, but are selected based on a defensible, risk-based rationale.
Organizations can tailor controls in several ways:
- Applying scoping considerations to eliminate unnecessary controls.
- Selecting compensating controls in cases where the standard control is not feasible.
- Assigning parameters within the controls to meet specific needs.
- Supplementing the baseline with additional controls for higher-risk scenarios.
In addition, organizations can create overlays to address the unique requirements of specific technologies, such as industrial control systems or cloud environments. These overlays provide pre-tailored baselines for particular communities of interest, facilitating the adoption of best practices.
Common controls and the shared responsibility model in cloud computing
The concept of common controls is especially relevant in cloud computing, where it aligns with the shared responsibility model. In this model, the cloud service provider (CSP) is responsible for the security of the cloud, while the customer is responsible for the security in the cloud.
From a NIST common controls perspective:
- CSP-Managed Controls: Many foundational controls, such as physical security, environmental protection, and network infrastructure, are common controls managed by the cloud provider. The customer inherits these controls simply by using the service, typically through service agreements and published audit reports.
- Customer-Managed Controls: The customer is still responsible for system-specific and hybrid controls that protect their own data, applications, and configurations. This includes identity and access management (IAM), data encryption, and network configurations.
- Collaboration: Both the CSP and the customer must understand their roles to avoid security gaps. Clear documentation and understanding of the shared responsibility model are crucial for a robust cloud security posture.
Benefits of NIST common controls
Leveraging NIST's approach to common controls offers organizations significant benefits:
- Increased Efficiency: Prevents the redundant implementation of the same security control across multiple systems, saving time and resources.
- Cost Reduction: Centralized management of common controls reduces the overall cost of security and compliance.
- Improved Consistency: Ensures a uniform level of security across all applicable systems by standardizing control implementations.
- Streamlined Audits: Centralized control implementation and documentation simplify the assessment and authorization process.
- Defensible Posture: Decisions on tailoring controls are supported by a risk-based process, making the security posture more transparent and justifiable.