WordPress Backdoor: Top Cause For Re-Infection

In most cases, when a hacker attacks a website, they leave behind a malware that will enable them to sneak back again in the future. A WordPress backdoor is the deliberate insertion of malicious codes in a WordPress website to allow the hacker to exploit the site again and again in the future. Websites using other CMS are not exempted from this menace either. If you find yourself dealing with almost the same hacking issue now, it is possible that even after doing thorough malware cleaning, your WordPress website might be getting infected again and again. This is a strong sign that WordPress backdoor may be hiding in your files and codes.

Why WordPress backdoor is harmful?

A backdoor usually indicates a severe problem on your website. They can be symptoms of a spam link that redirects your website traffic to spammy pages where they can get conned. They can also be indicators of hackers using your website as a host for pervasive attacks. It shows that the bad boys are attempting to access or have already accessed your site and are controlling it to serve their purpose.

How to detect a WordPress backdoor?

In most cases, back-doors dodge webmasters’ attention because hackers smartly disguise them between the databases and the legit files. You can easily confuse a backdoor with authentic codes, making them a hard nut to crack.

There are several types of WordPress backdoors on the basis of their complexity. Understanding them will help you have an idea when it comes to detecting a WordPress backdoor.

Complex Back-doors

  1. Complex and big backdoor codes usually have several lines of codes. The following code snippet is an example of such backdoors. Some hackers can obfuscate the code to avoid detection.

Simple, one-liner backdoors

  1. These consist of basic commands in one line. The hacker can run such a command on your website server to achieve their ill intention.

CMS specific backdoor

  1. Of late, cyber threats that insert backdoor codes in PHP based CMSes have increased. For example, hackers use the following classic piece of code to download a text file’s contents and upload it on /wp-includes/class.wp.php of WordPress.

How to remove a WordPress backdoor?

In most cases, people forget to remove backdoors from their websites, even after doing thorough malware cleaning and post hack rituals. You need to know that removing malware is not enough, as hackers may re-enter your website through backdoors that you’ve left unclosed and untreated.

So, how do you go about removing these backdoors? You can use these tested and proven techniques to remove WordPress backdoors:

1. Scan For foreign files

Are you finding it hard to categorize a code snippet using the above two methods? What you need to do is to check each function and command in it manually. Approve the legitimate ones and get rid of any alien command.

You can use an in-depth malware scanner for this purpose. Alternatively, a full-fledged security audit can also reveal all those hidden backdoors as well as loopholes in your security system.

2. Audit Server Logs

Your server logs can reveal a lot about file modifications, date of modification, IPs used to connect to your server, and more. A careful review of these logs can reveal a lot about changes on your website which you missed somehow.

To see these logs, log into your server account. Go to the admin panel. Now for different servers, this may vary a little. But in most cases, you can find the server logs under the Settings option.

3. Check common targets

Some files on the WordPress website is a more coveted target than others. The wp_config.php is one such file. So are the plugin and theme files. Usually, these are common locations for a backdoor insertion. Hence, scanning these files is a must when detecting backdoors on a WordPress website.

4. Cross-check against authentic files

After you have looked for backdoor in the most obvious locations, you should check all your files, including core, plugin, and theme files against your backup’s uninfected files. Each of the uninfected files has a checksum, which is simply a digital signature that you can use to check whether the existing files have malware or not.

Additionally, Drupal, WordPress, Magento, Opencart, and other CMS come with their own set of core files. You can check your existing files against your CMS core files to smoke out any unwarranted addition or modification to your core files.

If any anomalies are found, remove them and test your website.

5. Blacklist commonly identified harmful codes

Security experts have already identified common WordPress backdoors. Therefore, you should be able to deal with them. Much of the work has already been done. I would suggest that you blacklist them in advance. It will solve half of the problem as any hacker trying to insert a blacklisted backdoor on your site will likely meet a roadblock. Be sure to find documentation of these backdoors online.

Tips on preventing a WordPress backdoor

Now that you have successfully eliminated WordPress backdoors don’t forget to prevent them from sneaking back. You don’t want to spend your time and resources solving the same problems. Here are some of the fantastic tips that will come in handy:

After removing the hack,

  • Update your extensions, plugins, and themes to the latest versions.
  • Replace your passwords with strong and hard to guess ones
  • Use a website firewall to add an extra layer of security to your online resource.
  • Install a malware scanner that runs automatic and intelligent scans on your website on a 24/7 basis.
  • Update your software

Conclusion

Detecting and removing a WordPress backdoor is a vital process for every web owner. Otherwise, hackers can easily get back to your site and do significant damages that will cost you a lot. If you don’t have time or skills for this process, I suggest that you employ security experts to do the same. Furthermore, secure your website with a robust security solution to prevent backdoors in the future.