What is Crypter?
A crypter is a software that can encrypt, obfuscate and manipulate malware or a RAT (Remote Access Tool) tool to potentially bypass security products such as anti-viruses.
Encryption Process
For creating a simple crpyter, I will be using the following process:
- Generate a key with random characters & seed (32 characters hard-coded as of now)
- AES Encrypt #1 — Initialize the state array with the block data using the key
- AES Encrypt #2 — Generate IV (Initialization Vector) using block size + length of shellcode
- AES Encrypt #3 — Run the encryption process using the block and IV
- Base64 encode the results
Decryption Process
- Base64 decode the results
- AES Decrypt #1 — Initialize the state array with the block data using the key
- AES Decrypt #2 — Check if length IV is equal to the block size
- AES Decrypt #3 — Run the decryption process using the block and IV
- Return the decrypted string
I chose Go programming language to create the crypter.
