Many of you have learned about the OSI and many do not get how this is applicable beyond foundational knowledge.  I would like you to take another look at the OSI model and each layer discuss a possible security risk you see in each layer.  You will see a common theme by the end of the discussion.

Example:  Use only as example!

This week we discuss the security vulnerabilities that are found in each layer of the OSI model.  The physical layer is up first.  Vulnerabilities in the physical layer have been discussed extensively in previous weeks.  One possible security risk is for an adversary to infect a USB drive and then physically plug it in to a networked device.

The next layer is the data link layer.  It is the layer responsible for the transmission of data between nodes.  A security threat in this layer would be for a potential adversary to corrupt or alter data that is about to be sent through the node.  This would subsequently alter the data that is transmitted form its original and intended form.

The network layer is responsible for routing messages through different networks.  A vulnerability here could be a data worm that has infected a device in one network, being transported via the network layer to another network.  The worm will then be able to infect the devices within the new network.

The transport layer is the first in the upper layer and is responsible for breaking messages down in to pieces before sending them onward.  A potential vulnerability here is for the interception of unencrypted messages being sent through the transport layer by an adversary.

Session layer is next and is responsible for passwords exchanges, log offs, and termination of connections.  A vulnerability here would be an adversary keeping the gateway open and preventing the session layer from terminating the connection.  This would allow the adversary access to the data protected beyond the password gateway.

The presentation layer provides conversion service which cause character change sequences.  A vulnerability here could be an adversary corrupting the change sequence which would produce the incorrect data once it has been converted.

The final layer, the application layer is the layer most responsible for communication of the various applications being utilized.  One of the vulnerabilities present here would be the potential for a virus to cause the application layer to redirect data that flows through it.  

One of the common themes I see running through here is the spread of corruption and viruses.  Each layer has the potential to spread malicious content.  The conclusion this brings me to is that each layer must be properly defended with modern security protocols.

Jacobs, S. (2015) Engineering Information Security : The Application of Systems Engineering Concepts to Achieve Information Assurance