System attacks — Take control of the stronghold

We have seen in the and that it is possible for an ill-intentioned person to map a network, even if it is protected by security equipment, but also, while remaining at a distance, to harm this network by, for example, altering its routing functions, deceiving some of the equipment it hosts by usurping IP addresses and many other techniques.

We also discovered that machines placed on remote networks could themselves fall prey to the hacker, either to access the information they contain, or to use them as a "rebound" platform to gain access to other equipment, such as the firewall. from the network it protects, or a secondary system in a three-tier architecture, for example.

So far, the hacker has only worked on level 3 of the OSI model of the TCP/IP protocol. While he has discovered the existence of listening network services, he is still unsure whether he can use a particular port to carry out his attack. He's still missing one piece of information: which is the most interesting weak point?

Here, we'll look at the concept of a weakness, and the consequences it can have for a hacker, and vice versa for the victim. Of course, assessing the presence of a particular weakness requires us to consider not only the network layer, but also the higher layers which offer more possibilities.