SierraOne

SierraOne is a simple shared reverse shell over Discord, based on SierraTwo which works over Slack. The idea is to have a shell everyone can play around with during a CTF. Also, we like using Discord as @ExploitStudio.

Usage

SierraOne only supports Python 3.x.

Direct Usage

Windows

Not available. Instead, refer to building to build an .exe for Windows.

Linux

$ sudo apt install python3-pip
$ pip3 install -r requirements.txt
$ python3 SierraOne.py

Building

To build an executable:

$ sudo apt install python3-pip winbind wine winetricks
$ wget https://www.python.org/ftp/python/3.8.2/python-3.8.2-amd64.exe
$ wine python-3.8.2-amd64.exe
$ pip3 install -r requirements.txt
$ wine pip install -r wine_requirements.txt
$ python3 builder.py -o <TARGET SYSTEM>

BE SURE TO ADD PYTHON TO PATH WHEN INSTALLING WITH WINE

The following commands will setup Wine with 64 bit Python 3.8.2 on your system. <TARGET SYSTEM> can be either Windows or Linux. After building the executable, check the dist folder for your exectuable.

For example, running python3 builder.py -o Linux on a 64 bit Linux will generate a 64 bit executable. Same logic applies for -o Windows. If you want to generate a 32 bit executable, you'd have to install 32 bit Python instead of 64 bit (on your Linux and/or Wine).

If built for Windows:

• The executable's name will be msdtc.exe
• Executable will automatically minimize and hide itself

If built for Linux:

• The executable's name will by system.

Configuration

To use SierraOne, create a new server or be a part of a Discord server where you are an admin. Afterwards go to Discord Developer Portal and create a new application. In your application's settings, go to the Bot tab and turn your application into a bot. Then, go to the OAuth tab and tick Bot in Scopes and Administrator in Bot Permissions. Then, use the generated link to add the bot to your server.

Finally, copy Token in Bot tab of Discord Developer Portal and copy Server ID from Widget tab found on your Discord server's settings and paste the said info to their corresponding places config.py.

Optionally, you can integrate Mega in config.py, where the SierraOne will upload files larger than 7.5 MB and up to 105 MB to your Mega account. Otherwise, files larger than 7.5 MB and up to 30 MB will be split into 7.5 MB parts and uploaded over Discord.

Notes

• Although SierraOne could be used for pentesting, it's highly discouraged to do so. This is because Discord keeps records of all chat history, which might lead to disclosure of confidential data. It is recommended to pack/crypt the binaries before use.
• The traffic flows through Discord (and optionally, Mega Upload) therefore generating IoC's and rules for Sierra should be harder than your regular reverse shell.
• Upon launch, SierraOne will connect to the Mega (if the credentials are present) then connect to Discord. Upon connecting to Discord, it'll check the server for a category matching the category prefix. If there are no categories matching the prefix, a category matching the prefix will be created. By default, this is SierraOne. Afterwards; in a similar fashion, SierraOne will look for channels matching the channel prefix. If there are no channels matching the prefix, prefix-1 will be created. By default, this is sierra-hotel-1. However, if there is a channel (or channels) matching the prefix, SierraOne will get the largest number amongst the matching channels and add onto the largest number amongst the channels. That means if sierra-hotel-5 is the with the largest number amongst all present channels, the next channel will be sierra-hotel-6.
• You can only run one instance of SierraOne at a given time. This is due to Discord's API. To circumvent this, you can create multiple applications in Discord Developer Portal and run multiple instances of SierraOne under different, unique tokens.
• To close your shell, type shell_exit in the channel.
• To close your shell and delete the channel, type shell_delete in the channel.
• Although SierraOne could be used for pentesting, it's highly discouraged to do so. This is because Discord keeps records of all chat history, which might lead to disclosure of confidential data. It's recommended to pack/crypt the binaries before use.
• The channels will be created under the predetermined prefix. You can change this prefix in config.py

Known Bugs

• When uploading with Mega, if the upload takes a while, it's possible that the current shell will be closed and a new shell will be made. SierraOne will stop responding in the old channel, but continue to respond in the new channel.

Disclaimers

• This project is for educational purposes only. The developers and contributors are not responsible for any damage that may be caused by this program nor any consequences that may arise.
• By using this program you accept that the developers and contributors are not responsible if you violate Discord's Terms of Service, Discord's API Terms of Service and Mega Upload's ToS.
• With the current permissions of the app, SierraOne will have an admin access over your workspace.

Acknowledgements:

• Special thanks to Arszilla for helping out with the development and testing.