Defense-in-depth
At this stage, it is important to introduce the concept of Defense-in-Depth or DiD, which originally was developed by the National Security Agency (NSA) and the military to layer cyber defenses to better protect critical national technical infrastructure.
In a nutshell, this methodology helps the blue team design its security controls in a way that there is redundancy baked in, at every level. If one control were to fail or be compromised, the intention is to have at least one other control be able to defend the organization.
The layered approach of DiD is applicable to all levels of IT systems. The concept is applicable to building the security blueprint of a single endpoint device, as well as an entire organization with tens of thousands of assets. No organization can be adequately protected with a single layer of security. Hence, different defense controls work together to close any potential vulnerability. The main elements of classic DiD security include...