Compartmented Security Mode

What Does Compartmented Security Mode Mean?

Compartmented security mode is a security measure that limits the access of every user of a system, to only those parts of the system that the user needs to perform their function. This prevents users having access to data and/or functionality within a network or computer system that could present a security threat to the system through unauthorized use.


Compartmented security mode is one of four security modes that make up mandatory access control (MAC) systems.

Techopedia Explains Compartmented Security Mode

Historically, large scale systems were commonly compromised due to the wide access given to an organization’s users. This blanket access meant that many users would have access to data that they did not need access to to perform their job or function. This means that systems would be vulnerable for many potential reasons, such as; damage caused by disgruntled users or ex-employees whose access was not removed quickly, data altered by users with misplaced curiosity or poor judgment, deliberate tampering by data vandals and attempts made by fraudsters.

Allowing access to administrative areas of a system could allow a user to shut down entire systems and networks, or unauthorized access to sensitive data could be used to compromise an organization. Limiting such access provides a measure of security against unnecessary vulnerability limiting exposure to data theft or corruption.

The security issues caused by allowing users broad system access has led to the development of compartmented security mode as part of a suite of four security modes. These modes offer differing levels of data and system security and in are listed below in ascending levels of security control.

  • Dedicated security mode (All users can access all data).
  • System high security mode (on a need-to-know basis, all users can access limited data).
  • Compartmented security mode (on a need-to-know basis, all users can access limited data as per the formal access approval).
  • Multilevel security mode (on a need-to-know basis, all users can access limited data as per formal access approval and clearance).

The formal use of these modes includes determination of the type of direct/indirect users, the data (including its classification and security sensitivity) and the functionality and data access that users need to carry out their duties. A non-disclosure agreement (NDA) forms part of the security mode mandatory requirements in all modes.


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Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.