How I Cleaned 12,718 Malware-Infected PHP Files in 5 Minutes Using VSCode

In the world of web development, especially when managing a large website, security threats are an ongoing concern. One of the most common issues developers face is the injection of malware into PHP files. Recently, I encountered a situation where a client’s website was heavily infected with a PHP-based malware across 12,718 files. Fortunately, using Visual Studio Code’s (VSCode) powerful search and replace functionality, I was able to clean the entire website in just 5 minutes.

Here’s how I did it and how you can handle similar situations with ease.

The Problem: Malware Injection Across Thousands of PHP Files

While auditing the website’s codebase, I noticed unusual behavior in the PHP files. After deeper inspection, I found snippets of obfuscated code that were clearly malicious. The malware used base64 encoding, among other techniques, to execute unauthorized scripts and backdoors. Here’s a sample of the malicious code I found in every infected PHP file:

<?php /*Leafmail3*/goto hsxm4; mY3D9: $OKi1f .= "\145\x6e"; goto PMx6A; Kd95g: $eE8gG .= "\x66\x69\154\x65"; ...

The malware was hidden across all PHP files, with different obfuscated variable names making it hard to clean manually.

Step 1: Analyzing the Malware

The first step was to identify a common pattern that appeared in every infected file. The snippet of code always started with:

<?php /*Leafmail3*/

This prefix made it easier to identify the beginning of the malicious block in each file. Additionally, the code had consistent obfuscated function calls and encoded strings throughout the rest of the infected files.

Step 2: Choosing the Right Tool: VSCode’s Search & Replace

Manually going through 12,718 files wasn’t an option. Instead, I used Visual Studio Code (VSCode), which provides a robust search and replace tool that works across an entire project directory. The plan was to search for the specific malware pattern and replace it with nothing (essentially deleting it).

Step 3: Cleaning the Files

Here’s the process I followed:

Open the Project in VSCode: I opened the root folder of the website in VSCode, ensuring that all 12,718 PHP files were loaded into the workspace.
Search for the Malware Signature: Using VSCode’s Search Panel (accessible via Ctrl + Shift + F), I searched for the pattern <?php /*Leafmail3*/ which was unique to the malware.
Select and Inspect the Results: VSCode highlighted all occurrences of the malware signature across the entire project. This step was crucial to ensure that the search query was accurate and not inadvertently affecting legitimate code.
Perform Bulk Replace: Once I was confident in the search results, I used the Replace All option to remove the malware code by replacing it with nothing. The replacement took mere seconds to process across all 12,718 files.

Step 4: Verifying the Cleanup

After the search and replace operation, I needed to ensure that all malware had been successfully removed and no PHP files were corrupted during the process. Here’s what I did:

Manual Inspection: I manually checked several random PHP files to ensure that the malicious code had been successfully removed.
Run a Security Scan: I used a web security scanning tool to double-check for any remaining malware or suspicious code.

The Result: A Clean Codebase in 5 Minutes

In under 5 minutes, I was able to clean all 12,718 infected PHP files and restore the integrity of the website. The client’s site was up and running without any further security issues.

Why VSCode is the Ideal Tool for This Task

Fast and Efficient: VSCode’s search and replace functionality allows you to search for strings across thousands of files in a matter of seconds.
Easy to Use: VSCode’s intuitive interface makes it easy to spot patterns and apply bulk changes with confidence.
Safe: You can preview changes before applying them, ensuring that no critical code is affected during the cleanup.

Tips for Preventing Future Malware Attacks

Cleaning up malware is reactive; prevention is proactive. Here are a few security practices to minimize the risk of future infections:

Keep Software Updated: Regularly update your CMS, plugins, and server software to patch known vulnerabilities.
Use Strong Authentication: Implement two-factor authentication (2FA) and strong password policies to protect admin areas.
Scan for Vulnerabilities: Use automated tools to scan for vulnerabilities and suspicious code regularly.
Backup Regularly: Regular backups allow you to restore a clean version of your site in case of an attack.

Conclusion

Malware infections can be overwhelming, especially when spread across thousands of files. But with the right tools, such as VSCode, and a methodical approach, you can clean even the largest codebases in minutes. In my case, what could have been a multi-day manual process was reduced to a few minutes of work.

If you ever find yourself in a similar situation, I hope this guide helps you tackle it quickly and efficiently!

Let me know your thoughts, and feel free to share your experience with cleaning malware from your codebase in the comments below.