B64 Crypter by Tigerzplace

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Want to know what a crypter is? and how/why users use crypters. Then this blog article is for you because I am sharing my own and first-ever crypter (B64 Crypter by Tigerzplace). If you remember my method of crypting a rat server (crypt njrat with fud method), in that method, we encrypted the file using manual steps. I just automated all those steps and made a crypter with many advancements, like tweaking the string in reverse and adding polymorphic behavior to it. I used this same crypter for my own private use. I made it 6 months ago but am now sharing it with you guys for educational purposes. I made my way to cryptography and stuff related to cyber security, and I find it very helpful to understand such tools, so that I can understand where any anti-virus can fail to detect a file and how it can be bypassed. So if you are like me, then I hope you will also find it helpful. 

I'll be showing you how to use my crypter, but to give it an educational purpose touch, first you need to understand what a crypter is and what the related terms are associated with crypter, encryption, etc. 

B64 Crypter (Python Version)

What is crypter?

    - A crypter is a type of software that can encrypt, obfuscate, and manipulate malware to make it harder for security programs to detect. Hackers use it to create malware that can avoid detection by masquerading as a harmless program until it is installed.

Types of crypters

1. To make each encrypted file unique, static/statistical crypters use different stubs. Having a separate stub for each client makes it easier for malicious actors to modify or "clean" a stub after it has been detected by security software.
2. Polymorphic crypters are thought to be more advanced. They employ cutting-edge algorithms that make use of random variables, data, keys, decoders, and so on. As a result, one source file's output is never identical to the output of another source file.

B64 Crypter by Tigerzplace

To demonstrate the working of the crypter, I'll be using an async rat file (I also have tested njrat files; .NET type files can be encrypted with this crypter). BTW, the method is not just about rat encryption. You can demonstrate the method by encrypting any other file. This method is kind of my private crypter, which I made with the help of NYANxCat's tool and some Google searching to find an obfuscated PowerShell script. 

 

Before getting your hand on the crypter, understanding its working flow will help you in the cyber field. So, for those who are on a white hat and focus on the programming side, then the flow section of Crypt will be helpful. 

How B64 Crypter works?

• The crypter takes file.exe as input.
• Convert the bytes to Base64. Then take the B64 string and reverse it. 
• The final reversed string is used in obfuscated Powershell code that is executed using VBS script.
• The method is educational-based for learning, so if you don't want to use the crypter, you can manually follow the encrypting method by encoding file bytes into base64. and then use the base64 code to execute using obfuscated PowerShell scripts in VBScript. 
• The PowerShell loader is copied from NYAN-X-CAT

Encrypt a file with crypter.

How you can crypt a rat file/ or another file will be shown in this section. 

• First of all, you will need to download the crypter (B64 Crypter).
• But before that, the crypter is coded in Python, so you will need to download and install Python v3.+.
• If you are using any linux OS, then just update your python version. Otherwise, you can download it from their official website. The Python official site
• Once you've done with python installation, download B64 Crypter.
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• If the above download link is not working, then try this ALTERNATE LINK

• After downloading, extract the crypter files. They will also contain words.txt. Don't delete that file. It's better to open CMD in that location and run the crypter. If you can't do that, then simply double click the new crypter file and you will get a terminal.
• Drag the file you want to encrypt or provide the path of the file which you want to obfuscate.
• The next, thing is the startup name, as I am demonstrating the encryption on the rat file, and the rat file usually drops itself to the startup folder. If you are also using it for RAT file, then don't select the startup option while making your payload. 

I will not delve into non-educational applications in this article. The purpose is to demonstrate how certain tools can evade detection by antivirus software if the file's behavior or signature is modified or encoded in a manner that confuses the antivirus scan, which relies on file signatures. By encoding the file using base64 and then utilizing it in VBScript, it becomes more challenging for the antivirus software to identify the file signature. Consequently, the antivirus software fails to detect the file during runtime.

However, if you want to learn more about hacking, ethical hacking, penetration testing, android hacking, or maybe some other type of hacking, you might not know. So here you go, my post link where you will find complete courses for ethical hacking and many more hacking-related courses. 

Check it out here: https://www.tigerzplace.com/2020/03/Courses-for-Ethical-Hacking-Online-For-Free.html

B64 Crypter by Tigerzplace