The idea of cyber immunity is based on the following concepts:
These concepts are considered below. Then definitions of a cyber immune system and cyber immune approach are given.
Security goals and prerequisites
Information system security is not a universal abstract concept. Whether a system is secure or not depends on chosen security goals and prerequisites.
Security goals are requirements placed on an information system, which if achieved, ensure the secure operation of the information system in every possible scenario, taking into account the security prerequisites. Example of a security goal: ensure that data is kept confidential while using a communication channel.
Security prerequisites are additional limitations placed on the conditions in which the system is used, which if satisfied, will achieve the security goals. Example of a security prerequisite: cybercriminals must not have physical access to the hardware.
MILS concepts
In the MILS (Multiple Independent Levels of Security) model, a secure information system consists of isolated security domains and a separation kernel that controls the interactions between domains. The separation kernel isolates domains and controls the information flows between them.
Each attempted interaction between security domains is checked for compliance with certain rules, which are specified by the solution security policy. If an interaction is forbidden by the current policy, then it is not allowed (it is blocked). In a MILS architecture, a separate component (reference monitor) implements the security policy. For each security domain interaction, the reference monitor returns a decision (a boolean value) regarding whether the interaction complies with the security policy. The separation kernel calls the monitor each time one domain references another.
Trusted computing base (TCB)
Trusted Computing Base (TCB) is the set of all programming code, which if vulnerable will prevent an information system from achieving its specified security goals. In the MILS model, the separation kernel and reference monitor underpin the trusted computing base.
The trusted computing base's reliability plays a key role in ensuring the security of an information system.
Cyber immune system
An information system is cyber immune (or possesses cyber immunity) if it is separated into isolated security domains, all interactions between which are independently controlled, and is:
Cyber immune approach
The cyber immune approach is a way to build cyber immune systems.
The cyber immune approach is based on:
The specific method of dividing the system into security domains and the choice of a security policy depend on the security goals and prerequisites, the level of trust and integrity of individual components, as well as other factors.
Advantages of the cyber immune approach
The cyber immune approach lets you: