Security in the OSI model

Network security spans several layers in the OSI model. The following diagram gives us a breakdown of the different attack vectors and the representation of the percentage of attacks that succeeded in compromising an application in 2018:

As we can see, more than half of all attacks are represented by network layer attacks. These are spread out over multiple layers of the OSI model. Network attacks are most commonly layer 3 and layer 4 attacks, and they usually do the following:

• Attack the network service's availability by overloading the network link
• Attack the services on the network that deliver packets to the application such as routers, firewalls, and load balancers

The other half is shared by the other two types of attacks, which are intended to attack the application itself or the services that support the application being available on the internet:

• Application attacks that send malformed or malicious packets on layer 7 directly to the application
• Infrastructure service attacks, which include network attacks against the infrastructure supporting the application

In this section, we will look at all the relevant layers of the OSI model where our services typically reside and look at the approaches to security on these layers.