Backdoor Attack: Definition, Types & Prevention Tips

What is a Backdoor Attack?

A backdoor is an intentional or unintentional vulnerability created within a system, allowing unauthorized access. 

Initially, backdoors were designed to facilitate access to an application system without requiring someone, particularly a DevOps engineer or programming team, to log in first. 

Unfortunately, its original purpose of streamlining operational processes has now become a significant threat as it can serve as an entry point for hackers into a system.

In system management, security is a paramount aspect that is closely guarded to ensure data integrity and operational continuity.

These backdoor threats can be inserted into the code of a system or application, enabling their creators to access all files within the system without any restrictions.

What Are The Objectives of This Threat?

At first, the primary goal is to streamline the entry into a system without requiring a traditional login process. However, as these threats pose significant risks to website security, they are driven by the following objectives:

• Providing unauthorized access to attack operating systems, applications, or software.
• Stealing, altering, deleting, or compromising the integrity of credential data within the system.
• Spreading malware or spyware.
• Engaging in illegal activities such as website hacking, DDoS attacks, or other actions that can tarnish one's reputation.

Types of Backdoors

After understanding the definition, you should also be able to identify common types of it that is frequently used to compromise website security. Overall, these threats can be categorized into two common types:

1. System Backdoor

Attackers use this method to gain unauthorized access to systems that require authentication. Attackers often insert Trojan files into the system to enable them to manipulate or access the system without permission.

This type exploits weaknesses in the security of the operating system or software used by the target.

By planting Trojans or exploiting existing vulnerabilities, attackers can enter systems without the owner's knowledge.

Once they gain access to the system, attackers can engage in various harmful activities, including data theft, file destruction, or full system control.

2. Web Shell Backdoor

With this type, attackers can inject specific scripts into website files, granting them full control over the site.

This method is typically carried out by inserting code designed to provide unauthorized access to the website through scripts, with one common example being the use of the PHP programming language. 

How to Prevent Backdoor Attack

Prevention is surely better than cure. In order to bolster the security of your system or website against these backdoor threats, there are several steps you can take, such as:

1. Use Original Plugin

If you run a website with a Content Management System (CMS) like WordPress, ensure that the plugins you use are certified as original and official.

Using original WordPress plugins helps protect you from pirated plugins, which often contain malware scripts.

2. Keep Your Scripts and CMS Version Updated

Another crucial step is to keep your CMS version up to date because scripts or CMS that aren't regularly updated are more likely to introduce backdoor vulnerabilities, making it easier for attackers to compromise system security.

3. Do Malware Scans

Regularly scanning your hosting for malware is a step that can help safeguard your system against security threats.

In addition, scheduling malware scans allows you to identify and remove potential security threats, such as viruses, trojans, and other malicious code, as early as possible. 

4. Enable the Firewall

Firewalls act as defensive barriers that can prevent unauthorized access or attacks on your system.

By enabling a firewall, you can block unauthorized users from accessing your website or other suspicious access attempts by monitoring inbound and outbound traffic.

5. Limit the Use of Open-Source Software

You should pay more attention and awareness when using open-source software. Before using it, ensure that the software you choose has a good reputation, trustworthiness, and positive ratings.

While open-source code allows for transparency, meaning anyone can inspect the code for security, there's no guarantee that every open-source project is fully protected from potential threats.

Therefore, always make sure to download and install open-source software from trusted and official sources.

You can employ these measures to reduce the risk of hackers gaining unauthorized access and compromising your system's integrity. However, if a backdoor has already been installed into your system, what actions should be taken?

How to Handle A Backdoor Attack

If your website or application system has already detected the presence of a backdoor, here is a procedure for handling it.

In the world of cybersecurity, breaches through backdoors can take various forms. Sometimes, these breaches can be immediately apparent due to their impact on system functionality.

However, there are other situations where the threat may be concealed and difficult to detect for some time.

Before addressing it, you need to identify the existence of these security holes through a code analysis of the site because they are typically found in hidden PHP files on the web server.

Once successfully identified, you can remove them by first creating a comprehensive backup of all site files and databases. 

In accordance, you need to review the files that control access through the HTTP protocol, as this threat often arises through HTTP POST requests to specific files.

The removal process can be complex and time-consuming. Initially, you must be capable of identifying the illegal access code used, requiring a deep understanding of the programming language and code used to run the site.

Once the illegal access code is identified, you can then remove it entirely from the system. This removal process often requires the specialized expertise of cybersecurity professionals to ensure the threat is entirely eradicated, and the system is restored to a secure state.