Everything you need to know about the CIA classification in information security

Written by Ivar van Duuren

May 22, 2024

security island

Information security policies are a crucial part of any organization. It protects the confidentiality, integrity, and availability of data. But how do you determine what measures are needed for different types of information?

In this article, we take a closer look at what the CIA classification means and how it relates to standards such as the BIO and ISO 27001.

The 3 aspects of information security policies

Information security policies according to the CIA classification are about ensuring three core principles:

1. Availability

Availability refers to ensuring that information and IT systems are accessible and usable when needed. Without availability, it is difficult for employees to perform their tasks, and business processes stagnate. Examples of availability problems include:

  • Outages of servers or networks that prevent employees from accessing critical applications and data.
  • Overloaded systems cause response times to slow down and prevent users from performing their work.
  • Insufficient storage capacity makes it impossible to save or access files.

2. Integrity

Integrity is about ensuring that information and IT systems remain accurate, complete, and reliable, without unauthorized changes. A violation of integrity leads to incorrect decision-making, financial loss, and reputational damage. Some examples of integrity problems include:

  • Hackers manipulate or delete data.
  • Human error when entering or processing data.
  • Hardware failures or software errors that lead to file corruption.

3. Confidentiality

Confidentiality is about protecting information from unauthorized access or disclosure. A breach of confidentiality potentially leads to loss of competition, damage to reputation, and legal consequences. Some examples of confidentiality issues include:

  • Loss or theft of laptops, smartphones, or other mobile devices containing sensitive information.
  • Careless handling of paper documents containing confidential data.
  • Hackers break into IT systems and gain access to sensitive information.

A balanced approach, treating all three elements equally, is essential for effective information security.

Determine and apply CIA classifications

To determine what security measures are needed, many organizations use the CIA classification. This involves dividing information into different categories based on the level of availability, integrity, and confidentiality required.

  • First, determine how critical the availability of information is. Does it need to be accessible at all times?
  • Next, assess integrity: how bad is it if the information changes inadvertently?
  • Finally, you look at confidentiality: may this information become public knowledge?

Based on the CIA scores, you then assign security levels ranging from basic to very strict.

  • Level 0 (basic): Public information with no significant impact if compromised. Basic security measures are sufficient.
  • Level 1 (medium): Internal corporate information with limited impact if compromised. Standard security measures are necessary.
  • Level 2 (high): Sensitive data whose compromise causes significant damage, such as financial or reputational damage. Strict security measures are required.
  • Level 3 (very high): Highly confidential information with potentially catastrophic consequences if compromised. Maximum security measures must be taken.

By classifying information, organizations can prioritize and implement appropriate security controls. This prevents both over and under-security.

CIA and ISO 27001

ISO 27001 is the international standard for information security. It provides a framework for establishing, implementing, maintaining, and continuously improving an Information Security Management System (ISMS).

Although the ISO 27001 standard does not prescribe a specific CIA classification, information classification is an important part of risk management within an ISMS. Using the CIA triad gives you a better understanding of the security measures needed.

Many of the controls in ISO 27001 Annex A are related to the CIA principles. Think of access security for confidentiality, change management for integrity, and continuity planning for availability. The CIA classification helps select and prioritize the most relevant controls.

View ISO 27001 checklist

CIA and the Government Information Security Baseline (BIO)

The BIO is the basic standard for information security within the Dutch government. It provides a generic standards framework based on the internationally recognized ISO 27002 framework.

The BIO uses a risk-based approach in which the CIA classification plays an important role. Based on the CIA classification of information, appropriate security measures are selected from the BIO. The higher the CIA classification, the more stringent the controls required.

Conclusion

The CIA classification is a valuable tool for information security. By classifying information based on availability, integrity, and confidentiality, organizations get a handle on the security measures needed.

The CIA method aligns seamlessly with standards such as the BIO for government and the internationally recognized ISO 27001 standard. It forms an integral part of risk management and helps security officers to make well-considered choices in security policy.

Is your organization already working with the CIA classification? Careful classification is the first step to effective and proportional information security.

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