To recognize or prevent a backdoor attack, we need to know what they are. A malware or an exploit program that manages to bypass a system’s security measures to gain unauthorized access is called a backdoor.
A backdoor allows malicious users to create a safe passage in and out of a particular computational system without being noticed by anti-malware programs or other detectors. It will enable the hacker not only to access the system once but whenever they wish to.
They can remotely access the compromised system and its resources, including sensitive databases and information assets, whenever they want to.
Even though backdoors are mostly used by malicious users, not all backdoors are created to exploit. Sometimes, developers code backdoors for their systems to be remotely accessed while being far away.
These backdoors prove to be very helpful and convenient in terms of performance and user experience. Since potential hackers are always looking for safe passage, these intentional backdoors can prove to be the best ones.
Hackers are always keeping an eye on the administrative backdoors of an organization to exploit without being noticed.
An Example of a Backdoor
In the below example, we will be discussing a simple example of a backdoor written in python. There are essentially supposed to be two files. First, a socket server file named server.py.
In the server.py file, we intend to execute commands at the exploited system and get a response back. We import the socket module because we want to make a socket connection to the remote server.
In the next two lines, we define the IP address and the port for the server to connect to it remotely; we create and start the server in the following four lines. At line 8, our server is up and listening, we wait for the victim to start the malware we will create later, and when they do, our server accepts the request.
In the next line, we have initiated a loop, which will repeat sending commands and receiving outputs for as long as the server is alive. Inside the loop, we wait for the hacker to enter a command to be executed on the victim system, receive the output, and decode it.
Then there is the backdoor file named backdoor.py.
The backdoor file is supposed to connect the hacker’s computer to the victim’s computer. It is supposed to receive commands from the server.py file, execute them and respond the output back to the hacker after it gets connected.
The first two import lines are used to import the socket and subprocess. In the next four lines, define the IP address and port of the server, and once that’s done, they will create a socket client and connect to the server we already made.
There’s a while loop to repeat the processing. In contrast, the inside of the loop first waits for the hacker to send a command, and upon receiving, it decodes the command, executes the command, reads the output (success or error), and returns the output to the hacker.
How to Prevent Backdoor Attacks
The above experimental code tells us how powerful the Python language is for gaining access to the system and exploiting the resources; a backdoor is this easy to create.
Backdoor attacks are potent and dangerous because they can’t be detected and allow you to use the exploited system at root privileges.
Even though not all backdoors are malicious, they are all a vulnerability and, if not adequately protected, can cause a good deal of issues to authorities.
In enterprise organizations, it has become a trend now to use little or unknown trusted software packages. Organizations must be cautious when choosing software suites because those can prove to be the topmost vulnerability of any system.
Avoid downloading or using software that has less to no rating. Always choose software that is known and recognized and has an active support system. That reduces the chances of a hacker barging into an enterprise system by a fair amount.
They should also look into ways to minimize or monitor the use of open source projects. Often, the malicious code is wrapped in a sugar-coated open-source software, and the victim doesn’t even realize that they have created a backdoor into their system out of nothing.
An advanced anti-virus must always be in place and up to date. An antivirus capable of detecting and preventing malicious code from execution is the one we need to avoid and detect backdoor attacks. Sometimes, backdoors are installed using RATs and Trojans, so if those are detectable by the anti-virus, we’re already somewhat safe; never forget the importance of firewalls.
A firewall is designed to only grant access to authorized users, which helps prevent backdoor attacks. Network monitoring can just be another useful tool here. Advance monitors are capable of detecting malicious code snippets being transferred over the network and have built-in methods to prevent them from causing any harm as well.
