Among Us Wireshark Dissector

This repo contains a Wireshark Lua plugin to tag and analyze packets running on the Among Us UDP ports. It registers a new protocol and parses all packets. Currently, a lot of the protocol is fully analyzed. One caveat to this dissector is that it is stateless: if a field requires context from a previous packet, only the representation of the field as it appears in the packet will be shown (so numerical ID instead of resolving to a player name). However, this also means that the dissector will never be in a unknown bad state and give wrong info.

Installation

Install the lua plugin by cloning this repo and dropping the among_us_dissector.lua in your device specific plugin folder

• Read this: https://www.wireshark.org/docs/wsug_html_chunked/ChPluginFolders.html
• Windows: %APPDATA%\Wireshark\plugins
• macOS: %APPDIR%/Contents/PlugIns/wireshark if installed as an application bundle, or INSTALLDIR/lib/wireshark/plugins if installed seperately
• Linux/Unix-like OSes: ~/.local/lib/wireshark/plugins

Basic Usage

• First, open up wireshark on the interface that the client is sending through (localhost if running a local server)
• Filter output by protocol amongus in the filter bar
• View packet dissection in the tree

Filter examples

• View Among Us protocol UDP packets only: amongus
• View only Among Us reliable packets: amongus and amongus.packet_format eq Reliable or amongus and amongus.packet_format eq 1
• Remove Pings and ACKs from the view: amongus and !(amongus.packet_format eq Ping or amongus.packet_format eq Acknowledgement)
• View only GameData payload packets (reliable and unreliable packets): amongus and amongus.payload_type eq GameData
• The valid names/numbers for amongus.packet_format and amongus.payload_type and amongus.game_data are:

  •  Packet_Format = {
         Unreliable = 0,
         Reliable = 1,
         Hello = 8,
         Disconnect = 9,
         Acknowledgement = 10,
         Ping = 12,
     }
     
     Payload_Type = {
         CreateGame = 0,
         JoinGame = 1,
         StartGame = 2,
         RemoveGame = 3,
         RemovePlayer = 4,
         GameData = 5,
         GameDataTo = 6,
         JoinedGame = 7,
         EndGame = 8,
         GetGameList1 = 9,
         AlterGame = 10,
         KickPlayer = 11,
         WaitForHost = 12,
         Redirect = 13,
         RedirectMasterServer = 14,
         GetGameList2 = 16
     }
    Game_Data_Part_Type = {
        Data = 1,
        RPC = 2,
        Spawn = 4,
        Despawn = 5,
        SceneChange = 6,
        Ready = 7,
        ChangeSettings = 8
    }
    

Contributions and Issues

Contributions are welcome, just open a pull request to the dev branch.

Please open an issue on the Github tracker if you have a packet that doesn't get dissected (or gets dissected incorrectly)

Worked On:

• Fields for protocol. Packet Format (Reliable, Hello, etc) and Payload Type (JoinGame, GameData, etc)

To Do:

• Add more fields to allow easy filtering
• Document fields once created
• Better code style (Use tables to index and retreive parsing functions for each packet format type)
• Might be converted to a C plugin if I can get compilation working properly

Credits

Thank you to the Among Us Protocol Wiki and everyone in the Impostor discord