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. With backdoor trojan, unauthorized users can get around normal security measures and gain high-level user access on a computer, network, or software.

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What is Backdoor? (Definition & Examples) - Keep Your Privacy Well

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 extremely universal malware that is able to act differently from one case to the next. Thus, here is the explanation of how a single virus may be so omnipotent.

Backdoor virus integrates into the victim’s system on a very deep level. In contrast to the majority of other viruses, backdoors infiltrate into the computer as a driver. According to the ring hierarchical 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 among a dozen of 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? Apparently, you did, while allowing the system administrator to set your computer via a remote-access tool. Then imagine that someone is able to connect to your PC without your intention, and do whatever he/she wants. Crook can get any file stored on your computer, suspend and start any process - he can feel himself 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 are able to 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 to see that you are banned on websites or online forums you have never visited.

The ability to use a computer as you want 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.

Latest backdoors attacks:

How does the backdoor virus work?

As you can already conclude, all backdoors have some 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, too but doing it in a different manner 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 in order to make the “environment” more comfortable for being used in the future. 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 change and security changes is a thing 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 own registry keys and edit the existing ones even without entering the remote access mode - they can just use a command prompt.

Security is one of the most exploitable parts of Windows. While the majority of antiviruses are just apps, Microsoft Defender is a deeply integrated part of the system. It is managed by the operating system 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 in order to prevent 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 you have 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 the majority of 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 are talking 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, the majority of users do not give a lot of attention to slow down - they will likely reproach 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, the effective detection of 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 also get updates of 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.

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