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Understanding The Security Triad (Confidentiality, Integrity, and Availability)

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Most IT security practices are focused on protecting systems from loss of confidentiality, loss of integrity, and loss of availability. These three together are referred to as the security triad, the CIA triad, and the AIC triad. This article provides an overview of common means to protect against loss of confidentiality, integrity, and availability.
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If a system suffers loss of confidentiality, then data has been disclosed to unauthorized individuals. This could be high level secret or proprietary data, or simply data that someone wasn’t authorized to see. For example, if an unauthorized employee is able to view payroll data, this is a loss of confidentiality. Similarly, if an attacker is able to access a customer database including names and credit card information, this is also a loss of confidentiality.

Loss of integrity means that data or an IT system has been modified or destroyed by an unauthorized entity. This could be the modification of a file, or the change in the configuration to a system. For example, if a file is infected with a virus, the file has lost integrity. Similarly, if a message within an email is modified in transit, the email has lost integrity.

Availability ensures that data and systems are up and operational when they are needed. Or said another way, loss of availability indicates that either data or a system is not available when needed by a user. For example, if a Web server is not operational when a customer wants to purchase a product, the Web server has suffered a loss of availability.

Certifications that include the Security Triad

If you’re planning on taking the CompTIA Security+ exam, the (ISC)2 SSCP exam, or the (ISC)2 CISSP exam, you should understand what these terms mean and how they relate to IT security. Each of these exams may include topics on the security triad from these objectives:

  • CompTIA Security+ (SY0-201)
    • 5.1 Explain general cryptography concepts: Confidentiality, Integrity and availability
  • CompTIA Security+ (SY0-301)
    • 2.9 Exemplify the concepts of confidentiality, integrity and availability (CIA)
  • (ISC)2 SSCP Confidentiality, integrity, or availability are mentioned in each of the seven SSCP domains.
  • (ISC)2 CISSP Confidentiality, integrity, or availability are mentioned in each of the following CISSP domains.
    • Application Development Security
    • Cryptography
    • Information Security Governance and Risk Management
    • Security Architecture and Design
    • Telecommunications and Network Security

Protecting Against Loss of Confidentiality

Organizations protect against loss of confidentiality with access controls and encryption. For example, users are first required to authenticate and then access is granted to users based on their proven identity. In short, users are granted access to data via permissions. If users do not have permissions, they are denied access.

However, there are many other instances where someone can access data without needing to prove their identity. For example, any data sent over the wire can be captured with a sniffer. Additionally, any data at rest such as on a hard disk drive, or a portable USB flash drive, could be stolen and easily accessed. You can protect this data from loss of confidentiality with encryption.

Encryption converts plain text data into ciphered data. Ciphered data can’t be read (at least not easily) if received or intercepted by unauthorized individuals. It’s estimated that it’ll take hundreds of years for an attacker to crack many of the strong encryption methods in use today. In contrast, weak encryption methods (like WEP used with older wireless networks) can be cracked in seconds with the right software.

Many types of encryption algorithms are popular today. The Advanced Encryption Standard (AES) is a fast, efficient algorithm that is commonly used to encrypt data at rest. Trusted Platform Modules (TPMs) can encrypt entire hard drives which is especially useful for portable computers. S/MIME is used to encrypt (and digitally sign) email. Many other protocols such as SSL, TLS, IPsec, and others encrypt data sent over the wire either over the Internet or on internal networks.

Protecting Against Loss of Integrity

One of the common ways of ensuring integrity is with hashing. In short, a hash is a number and a hashing algorithm can calculate a hash for a file or string of data. As long as the data has not changed (and the same hashing algorithm is used), the hash will always be the same. The two primary hashing algorithms used today are Message Digest 5 (MD5) and Secure Hashing Algorithm 1 (SHA-1).

As an example, if you calculate the hash of the phrase “ILoveSecurity” with the MD5 hashing algorithm it will always be E7F8B292F4F5C2F98E5DF1435EB73D1B. However, if the phrase is slightly modified to “ILiveSecurity” (the “o” is change to an “i”) the hash is 2F088A01343CFD65B7BC4EB050503CB7. By comparing the two hashes and seeing that they are different, you know that the original data created by each of the two hashes are different.

One way hashes are used is by detection systems that calculate hashes of key files. The detection systems later check these files to determine if the hash is the same. If the hash has been modified, the file has lost integrity and is considered suspect. Similarly, users can send messages with a digital signature. The hash is calculated before the message is sent and the hash is sent with the message. The hash is calculated again when the message is received and compared to the original hash. If the hashes are different, the message has lost integrity. Even though a digital signature has a primary goal of providing authentication and non-repudiation, it still protects against loss of integrity.

Protecting Against Loss of Availability

Primary methods that organizations use to protect against loss of availability are fault tolerant systems, redundancies, and backups. Fault tolerance means that a system can develop a fault, yet tolerate it and continue to operate. This is often accomplished with redundant systems such as redundant drives or redundant servers. Backups ensure that that important data is backed up and can be restored if the original data becomes corrupt.

Fault tolerance and redundancies can be implemented at multiple levels. For example, RAID-1 is a mirror of two drives; if one drive fails, the other drive still holds all the data. RAID-5 (striping with parity) uses three or more drives and uses parity to recreate the data if any drive fails. RAID-10 combines the features of a RAID-1 with the features of a RAID-0 array.

You can add redundancies for servers by configuring them in a failover cluster. Failover clusters include two or more nodes (servers within the cluster) and if any node fails, other nodes can take over. This happens automatically with very little impact on end users.

Alternate sites can be used if a disaster takes down an entire location. A hot site is up and operational with all the equipment and data needed to take over at a moment’s notice. A cold site is an empty building with electricity and running water but needs equipment and data to be moved to the alternate location before it can be used. Hot sites are very expensive, and cold sites can take a long time to become operational. A warm site strikes a balance between a cold site and a hot site.


If you’re preparing for a security based certification exam, you should have a good understanding of confidentiality, integrity, and availability. You should also know the basic methods used to prevent and detect losses in any of these areas. Good luck!

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