Villain: Windows & Linux backdoor generator and multi-session handler

Villain

Villain is a Windows & Linux backdoor generator and multi-session handler that allows users to connect with sibling servers (other machines running Villain) and share their backdoor sessions, handy for working as a team.

The main idea behind the payloads generated by this tool is inherited from HoaxShell. One could say that Villain is an evolved, steroid-induced version of it.

Approach

A few notes about the http(s) beacon-like reverse shell approach:

Limitations

• A backdoor shell is going to hang if you execute a command that initiates an interactive session. For more information read this.

Advantages

• When it comes to Windows, the generated payloads can run even in PowerShell constraint Language Mode.
• The generated payloads can run even by users with limited privileges.

Important Notes

1. Villain has a built-in auto-obfuscate payload function to assist users in bypassing AV solutions (for Windows payloads). As a result, payloads are undetected (for the time being).
2. Each generated payload is going to work only once. An already-used payload cannot be reused to establish a session.
3. The communication between sibling servers is AES encrypted using the recipient sibling server’s ID as the encryption KEY and the 16 first bytes of the local server’s ID as IV. During the initial connection handshake of two sibling servers, each server’s ID is exchanged with clear text, meaning that the handshake could be captured and used to decrypt traffic between sibling servers. I know it’s “weak” that way. It’s not supposed to be super secure as this tool was designed to be used during penetration testing / red team assessments, for which this encryption schema should be enough.
4. Villain instances connected with each other (sibling servers) must be able to directly reach each other as well. I intend to add a network route mapping utility so that sibling servers can use one another as a proxy to achieve cross-network communication between them.

Install & Use

Copyright (c) 2022 Panagiotis Chartas (t3l3machus)