How to give fake GPU info to site

I need to create web browser using CefSharp.Wpf with ability to give fake data to site for example CPU cores, browser plugins, platform name etc. There are site that can retrieve all this info: https://www.deviceinfo.me/

My quesiton is: How to hide GPU info from this site? Using javascript or CefSharp functionality

I have tried to redefine WebGLRenderingContext.getParameter method, which gives an info about GPU renderer and vendor:


var canvas = document.createElement('canvas');

var gl;

try {
  gl = canvas.getContext("webgl2") || canvas.getContext("webgl") || canvas.getContext("experimental-webgl2") || canvas.getContext("experimental-webgl");
} catch (e) {
}

var oldParam = WebGLRenderingContext.prototype.getParameter;


WebGLRenderingContext.prototype.getParameter = function(parameter){

    console.log("we have guests");

    if(parameter == debugInfo.UNMASKED_RENDERER_WEBGL){
         return "GTX 1080";
    }

    if(parameter == gl.getExtension("WEBGL_debug_renderer_info").UNMASKED_RENDERER_WEBGL){
        return "GTX 1080";
    }

    if(parameter == debugInfo.UNMASKED_RENDERER_WEBGL){
        return "NVidia";
    }

    if(parameter == gl.VERSION){
        return "GTX 1080";
    }
    return oldParam(parameter);
};

I expected to completely redefine this method and return some fake info, but when i called gl.getParameter(param) again, it still gave me an old gpu info

Solution

If you still want Canvas2D and WebGL to still work then you can't hide since they can finger print by actually rendering.

You could disable them with

HTMLCanvasElement.prototype.getContext = function() {
  return null;
};

Though the fact they don't exist is also a data point.

Otherwise your wrapper appears to have some issues.

First you really should set the function before creating the context.

Second your last line should be

   oldParam.call(this, parameter);

Also you didn't show debugInfo but you can use WebGLRenderingContext instead or you can just hard code the numbers

As for http://www.deviceinfo.me you need to make sure your patch runs in all iframes and workers before any other JavaScript.

WebGLRenderingContext.prototype.getParameter = function(origFn) {
  const paramMap = {};
  paramMap[0x9245] = "Foo";         // UNMASKED_VENDOR_WEBGL
  paramMap[0x9246] = "Bar";         // UNMASKED_RENDERER_WEBGL
  paramMap[0x1F00] = "Nobody";      // VENDOR
  paramMap[0x1F01] = "Jim";         // RENDERER
  paramMap[0x1F02] = "Version 1.0"; // VERSION

  return function(parameter) {
    return paramMap[parameter] || origFn.call(this, parameter);
  };
}(WebGLRenderingContext.prototype.getParameter);

// --- test

const gl = document.createElement('canvas').getContext('webgl');
const ext = gl.getExtension('WEBGL_debug_renderer_info');

show(gl, gl, [
  'VENDOR',
  'RENDERER',
  'VERSION',
]);
if (ext) {
  show(gl, ext, [
    'UNMASKED_VENDOR_WEBGL',
    'UNMASKED_RENDERER_WEBGL',
  ]);
}

function show(gl, base, params) {
  for (const param of params) {
    console.log(param, ':', gl.getParameter(base[param]));
  }
}