This analysis in only for physical attacks.

It compares the time required by the attacker to go through the border, against the time to detect plus the time to react.

Let’s see an example. There are 3 zones: external, intermediate, and internal. There is an external attacker that tries to get inside. The attacker requires 10 minutes. The border systems take 5 min to detect, and reaction requires 1 hour.

 

The system has a problem: the attacker is too fast for the protection system:

 

We can improve reaction for the target phase

 

The attack is blocked

 

The time balance may be not so clear, and the chances of the attacker to succeed are not zero:

 

Attack paths where reaction time is fast enough, are removed. PILAR retains those where speed is not enough.