Earlier this week, I was speaking to a prospective client and I mentioned open ports. The client had a puzzled look and asked me to explain what I meant by an open port, to a non technical person.
I thought this would make an excellent blog post so here it is.
Most computer related hardware and peripherals communicate with the internet and each other through their ports.
The majority of hardware items such as PC’s, mobile devices, printers etc. will have hardware ports that we are all probably familiar with such as USB ports or ports for your SD cards, however these are not the ports that we are speaking about at the moment (Those types are a blog post all by themselves!).
The ports that I am referring to are communication ports, which allows the computer or device to communicate to other such devices, usually across a network or the internet. Each port has a number and an associated service, for example port 80 is the port that is commonly associated with HTTP, which may sound familiar.
HTTP is a protocol that allows a client device such as your computer to receive messages from a web server, which allows messages to flow in either direction. These messages carry data, for example a web page.
A port can be thought of as a door way, in physical terms that allows data to flow in both directions, into the computer and out of the computer.
Above I highlighted one service that runs on one port, but a computer will be running numerous different services that require numerous different ports to be open. This is the same for networked devices and servers.
An open port is a port that is ‘open’ for communication. This would be like having the front door of your house open.
Most systems will require some open ports to carry out their intended purpose, however some systems will unintentionally leave ports open, or have ports open by default when you purchase them.
In November 2018, a ‘Hacker’ realised that a certain brand of printer, when sold, had a certain port open by default and required the new owner to manually close the port using the system settings. As you can imagine most new owners weren’t aware of this security risk.
The ‘Hacker’ using a free and available resource (Shoddan.io), searched the internet for every printer he could find that matched the make and model. He successfully found a large number of printers meeting the criteria, reported to be in the hundreds of thousands.
To take advantage of this risk and to bring awareness to their owners, the ‘Hacker’ created a script (computer program) that sent messages to all of these printers and instructed them to print out his message.
At the time the ‘Hacker’ was interested in a You Tube channel that was actively campaigning for more subscriptions and he used his new found security risk to ask people to subscribe.
The full story can be found here https://www.theverge.com/2018/11/30/18119576/pewdiepie-printer-hack-t-series-youtube
This story although pretty humorous highlights what can happen if a device has a port open.
Most networks will have open ports, sometimes allowing communication protocols that could be considered vulnerable to exploitation, which could lead to somebody gaining access to your network, bypassing any security protocols in place.
It is important therefore no matter how big or small your network(s) are, to understand and have knowledge of, which ports you have open and exposed to the internet.
I hope this makes sense and helps explain what an open port is.
Thanks
James
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