What Is a Backdoor? Definition, Examples, Backdoor Attacks

A backdoor is a technique in which a system security mechanism is bypassed undetectable to access a computer. For example, with a backdoor trojan, unauthorized users can get around specific security measures and gain high-level user access to a computer, network, or software.

You may be interested in taking a look at our other antivirus tools:
Trojan Killer, Trojan Scanner.

What is Backdoor? How to Prevent Backdoor Attacks (2022) | Gridinsoft

What is Backdoor?

Isn't a back door the best way to break into someone's house to steal a bike? The same is true for computers. Nothing can be so effective for data stealing, remote malware injection, and other uncoordinated actions.

Backdoors is a big subspecies of viruses, which is used for different targets through the last 10 years. Of course, the malware examples that reportedly had the same functions as backdoors appeared even earlier, but no one classified them exactly as the backdoors. As of their nature, backdoors are universal malware that can act differently from one case to the next. Thus, here is the explanation of how a single virus may be so omnipotent.

Protection rings hierarchy
Protection rings in the CPU

Backdoor virus integrates into the victim’s system intensely. In contrast to most other viruses, backdoors infiltrate the computer as a driver. According to the hierarchical ring system, drivers are located on Ring 2 and executed with a bigger priority than the operating system. Anything which runs on Ring 2 can control all processes that are located on Ring 3 and Ring 4, where OS and installed software run. Hence, integrating a virus on such a deep level means getting control of the whole system. Backdoors are just one example of a dozen other viruses that exploit that ability. A perfect example of a riskware that integrates itself on a driver level is a Mimikatz hack tool.

So what can backdoors do?

Did you ever see that your mouse pointer moves without your command? You did this while allowing the system administrator to set your computer via a remote-access tool. Then imagine that someone can connect to your PC without your intention and do whatever they want. Hackers can get any file stored on your computer, suspend and start any process - he can feel like a PC owner. In some cases, cybercriminals can even launch your PC remotely, so you must not even turn it on by yourself.

Therefore, fraudsters who control the virus can manage your computer remotely, in the manner they want. There is no strict scenario of how the situation will be. Backdoors, especially the lightweight variants of ones, are often used to unfold the botnet. Computers infected with the backdoor virus are running in a so-called “zombie mode”: they are used as usual by their real owners until they receive a command from the control server. Then, those machines start spamming or DDoS attacks, using the account of their legit owner as a disguise. You will surely be surprised that you are banned on websites or online forums you have never visited.

The ability to use a computer allows you to install the programs you want. Hence, cyber burglars often use the currently active backdoor to inject various other malware into your system. That does not mean that each backdoor case will lead to another virus injection, but the possibility is always there.

Backdoors Attacks in 2022:

How does the backdoor virus work?

As you can already conclude, all backdoors have similar details with remote administration tools. Exactly, some of the illegal remote tools are detected by antiviruses as backdoors. They grant access to the persons who control it but do it differently than remote administration tools do. Malware uses exploits in various system elements to perform this action. Unfortunately, Windows is full of various vulnerabilities, so crooks may break into your system even if you have the last security patches installed.

After being injected, the backdoor adjusts the system to make the “environment” more comfortable for future use. For this purpose, the virus adds a specific connection by sending the command through the command line, changes registry keys, and modifies the security settings. While the first act is quite easy to understand, registry key changes and security changes are things that must be explained.

There is an obsolete feature in Windows which allows you to edit the registry from the remote computer. This ability is a perfect source for exploitation, so fraudsters rarely forget to turn it on. Remote registry editing allows the fraudsters to add their registry keys and edit the existing ones even without entering the remote access mode - they can use a command prompt.

Security is one of the most exploitable parts of Windows. While most antiviruses are just apps, Microsoft Defender is a deeply integrated part of the system. The operating system manages it through the rules set in Group Policies. He can be disabled through these settings in several clicks, and virus creators know about that ability. Malware stops the Defender from preventing the alarm - an embedded antivirus has quite good detection databases, despite being extremely unreliable. One day, you may discover that your Defender is “asleep”, and nothing can wake it up.

Can I detect the backdoor virus by myself?

You will barely understand if your computer is infected when the backdoor is designed well and used properly. The only chance is when the criminals who manage the virus connect to your PC and start actions. You will see the console windows opening chaotically, pointer moves, and apps opening without your intention. But in most cases, fraudsters wait for a week before using a freshly infected computer for their purposes. Through that term, they collect information about the activity hours of the user who owns this PC.

However, if we talk about the backdoors that add the victim’s PC into the botnet, you will see no symptoms. These viruses are stealthy enough to work simultaneously with the usual activity. The only sign you will spot is likely a PC slowdown. Nonetheless, most users do not give a lot of attention to slowing down - they will likely blame Windows.

The best way to detect such an unpredictable virus is to use anti-malware software. Examples like Microsoft Defender do not suit because of the mentioned reasons. However, effectively detecting backdoor viruses is a hard task, and not every antivirus solution is ready. To get the best protection, you will likely need to have a heuristic detection mechanism in your security tool and get updates on detection databases as often as possible. GridinSoft Anti-Malware can offer you both of these privileges: its databases are updated every hour, and it has an On-Run protection feature, which uses the heuristic mechanism to detect malware.

Frequently Asked Questions

What does "Backdoor application" mean?
Backdoor program — a specific malicious program that is created with an intent to gain unauthorized access to the victim's device. The term means the same as just the word "Backdoor". Cybercriminals use this kind of malicious program to get access remotely and then exercise their intended malicious actions. Threat actors can install backdoors both on hardware and software parts of a computer. Most types of backdoor programs exploit IRC backbone and receive their commands from mutual IRC chat clients.
What is the difference between backdoors and trojans?
Trojan virus is a kind of malicious program that pretends to be a legitimate program but instead it will steal the user's sensitive data or will spy on the victim's online activity. To deliver trojans to the victims, threat actors usually employ various social engineering attacks like sending email with a malicious attachment or some free to download file. Backdoor viruses also belong to the trojan malware family. They also get hidden inside legitimate looking programs but once on the victim's device the backdoor will begin conducting its secret malicious activity after gaining primar access to it. Among the various activities it will also include executing commands given from threat actors
What is a website backdoor?
Basically, website backdoors is a hidden entry point in your site that for those who knows about the point it will present with unrestricted and unauthorized access to the resource. Website backdoors are very difficult to detect manually and in fact you can compare the process of finding the website backdoor with trying to find a particular hay in a barn that is full of hay. In other words to explain, website backdoor is a malicious code that can be deep hidden within regular, non malicious code on a site. Apart from this, backdoor malicious code can secretly reside in other different parts of a site. If the malicious problem is left unchecked the site will continue to be vulnerable to various cyber threats.
Do trapdoor and backdoor mean the same thing?
A computer trapdoor is another word for backdoor. Trapdoors can be created for a variety of reasons both legal and illegal. In its essence, trapdoors or backdoors provide secret and in some cases undocumented access to an online service, operating system or application. The use of trapdoors may vary from simple troubleshooting to illegal access.