18/08/2022
I started a red team assessment on a financial institution today and the first step they asked me to do was to bypass the NAC (Network Access Control).
Since I noticed all of their workstations have installed agents (like software) in order to join the network, I don’t think I could replicate and installed it on my own laptop. This would not be the way for me to access to their network.
I explored around and I noticed an employee was trying to print documents on a printer, I had a thought that the printer must have joined the network so the employees could simply just print the documents they need on their computers.
A printer is not a computer system, how could it joined the network without installing agent?
This had come to my mind and I made an educated guess:
Either the IP address (Static IP) or the MAC address of the printer was whitelisted.
I walked to the printer and tried to find more info about it, unfortunately it required admin’s password to view the network config and device’s info.
I then went to other floors to give a try and finally found a printer that I could view the details without password, I recorded the IP address and the MAC address of the printer (The IP address appeared to be in the same network as other employee’s workstations).
I tried to pretend that I was the printer.