Use NMAP to identify the target machine (192.168.4.0) among (192.168.4.0/24)
Use NMAP to identify the service: port 8080/TCP
Discover the vulnerability: the same key is simply XORed with the plaintext for all encryptions
Encrypt a custom plaintext
Retrieve the ciphertext from /show_encrypted_notes
Recover the key: XOR the plaintext with the cyphertext
Use the FinalAnswer tool