HTB Sherlocks Einladen

Hello folks! I am almost done with Sherlocks Einladen, except the AES-256 decryption question. I disassembled the malware with dnSpy and found the base64 encoded Ports value and the key. But couldn’t find the IV. I tried to decrypt AES-256 CBC using openssl, but it doesn’t seem possible to decrypt without IV. Could you guys have an idea or an hint to give me? Thanks!!!