What is a Backdoor and How to Protect Against it

“Did I forget to lock the door?” This scary thought usually comes to mind when you’re already halfway across town and it’s quite disconcerting. Leaving a door unlocked makes it easy for anyone to enter and take whatever they please.

It’s the same with backdoor attacks, but instead of breaking into your house, criminals enter your computer system to steal data, hijack resources, or plant spyware.

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What is a Backdoor?

A backdoor, or a backdoor attack, is a type of malware that manages to bypass security restrictions to gain unauthorized access to a computer system. In simpler words, a backdoor is a piece of code that allows others to go in and out of a system without being detected.

One this has been done, remote access is granted and hackers are able to get back into the system whenever they want at a later stage. They can then access computer resources, such as databases and file servers, to steal information as well as issue system commands and install further malware.

How are Backdoors Created?

There are various types of backdoors that can be created, and not all of them have malicious intent. We’ll discuss them below.

Administrative Backdoors

Backdoors are not always malicious. Sometimes software developers deliberately code backdoors into their applications as a legitimate point of access for remote administration, diagnostics, troubleshooting, or system tests.

These intentional backdoors are convenient and can improve performance and user experience. However, they can also be exploited by hackers to gain access. Hackers often look for administrator backdoors and those known only to the software vendors to break into systems.

In other words, backdoors are not always evil, but they do add another layer of vulnerability that hackers can exploit to gain unauthorized access to a system.

Security Organizations

In 2013, other backdoors gained notoriety when Edward Snowden leaked NSA documents to the media. The spy agency, in partnership with Britain’s GCHQ, had been pressuring software makers into installing backdoors.

The issue gained traction again in 2016 when the FBI attempted to force Apple to unlock an iPhone through a lawsuit. The legal battle ended when a private firm broke into the phone, but the public debate about security and privacy is likely to continue.

No matter what side you take on the issue, backdoors leave your system vulnerable to an attack and can give third parties access to your private data.

Malicious Backdoors and Remote Access Trojans

Hackers can also install their own backdoors into targeted systems with the help of a remote access Trojan, or RAT.  A RAT is a piece of malware code that includes a backdoor for administrative control on a specific device.

Usually, RATs make their way into the system by tricking the user into downloading them through social engineering and disguising them as legitimate files. For instance, a RAT can be disguised as an email attachment sent by a colleague, a social media link on a friend’s profile, or a video game to download. Once a RAT is installed, hackers can use the backdoor anytime they please.

Why are Backdoors Dangerous?

When it comes to security, unintended flaws and intentional backdoors are essentially the same. What makes any backdoor dangerous is that at some point it is bound to be discovered by a malicious hacker who will be eager to exploit it.

What are the risks of backdoors?

A remote hacker can access your device through a backdoor to:

  • Install other malware on the system
  • Steal data
  • Download additional files
  • Run tasks and processes
  • Control the device remotely
  • Download or upload files
  • Perform DDoS attacks on other computers
  • Change computer settings, including passwords and user credentials
  • Shut down, restart, or even “brick” the device

How do I Protect Against Backdoors?

A backdoor attacks is notoriously difficult to detect. In fact, many users are unaware of the backdoors that exist in their systems for weeks, months, or even years before an attack happens.

However, there are strategies you can use to reduce the risk of a breach.

Use an Antivirus

You should have an advanced antivirus in place that is capable of detecting and preventing malware and malicious attacks. Many backdoors are installed through RATs, Trojans, and other types of malware, so it is essential to install an antivirus tool capable of detecting such threats.

Looking for suggestions? See our top ten antivirus programs with firewalls here.

Use a Firewall and Network Monitoring Tool

Your antivirus should provide a firewall and network monitoring as a part of the security suite. A firewall grants access only to authorized users. A strong network monitoring tool can help guarantee that any suspicious activity— such as unauthorized uploads or downloads—are flagged and taken care of.

Any backdoor is a vulnerability that can be exploited.

Backdoors come in many shapes and sizes; they are created by developers or service providers for remote troubleshooting or other official reasons, or through malware. But, no matter who created it and why, a backdoor can be used to gain access for malicious intent. 

Backdoors are difficult to spot because hackers disguise them as regular files. The only way to tackle a backdoor attack is by using an antivirus, security scanners, and cleaners to block unauthorized backdoor access and to weed out any accompanying malware.

To prevent backdoor attacks, you should install a powerful antivirus with top-notch malware detection and prevention capabilities, a firewall, and a network monitoring tool.

About the Author

Sophie Anderson
Sophie Anderson
Cybersecurity researcher and tech journalist

About the Author

Sophie Anderson has spent the last 10 years working as a software engineer for some of the biggest tech companies in Silicon Valley. She now works as a cybersecurity consultant and tech journalist, helping everyday netizens understand how to stay safe and protected in an online world.