Hoping an expert can help me with a Selenium/Cloudflare mystery. I can get a website to load in normal (non-headless) Selenium, but no matter what I try, I can't get it to load in headless.

I have followed the suggestions from the StackOverflow posts like Is there a version of Selenium WebDriver that is not detectable?. I've also looked at all the properties of window and window.navigator objects and fixed all the diffs between headless and non-headless, but somehow headless is still being detected. At this point I am extremely curious how Cloudflare could possibly figure out the difference. Thank you for the time!

List of the things I have tried:

• User-agent
• Replace cdc_ with another string in chromedriver
• options.add_experimental_option("excludeSwitches", ["enable-automation"])
• options.add_experimental_option('useAutomationExtension', False)
• options.add_argument('--disable-blink-features=AutomationControlled') (this was necessary to get website to load in non-headless)
• Set navigator.webdriver = undefined
• Set navigator.plugins, navigator.languages, and navigator.mimeTypes
• Set window.ScreenY, window.screenTop, window.outerWidth, window.outerHeight to be nonzero
• Set window.chrome and window.navigator.chrome
• Set width and height of images to be nonzero
• Set WebGL parameters
• Fix Modernizr

Replicating the experiment

In order to get the website to load in normal (non-headless) Selenium, you have to follow a _blank link from another website (so that the target website opens in another tab). To replicate the experiment, first create an html file with the content <a href="https://poocoin.app" target="_blank">link</a>, and then paste the path to this html file in the following code.

The version below (non-headless) runs fine and loads the website, but if you set options.headless = True, it will get stuck on Cloudflare.

from selenium import webdriver
import time

# Replace this with the path to your html file
FULL_PATH_TO_HTML_FILE = 'file:///Users/simplepineapple/html/url_page.html'

def visit_website(browser):
    browser.get(FULL_PATH_TO_HTML_FILE)
    time.sleep(3)

    links = browser.find_elements_by_xpath("//a[@href]")
    links[0].click()
    time.sleep(10)

    # Switch webdriver focus to new tab so that we can extract html
    tab_names = browser.window_handles
    if len(tab_names) > 1:
        browser.switch_to.window(tab_names[1])

    time.sleep(1)
    html = browser.page_source
    print(html)
    print()
    print()

    if 'Charts' in html:
        print('Success')
    else:
        print('Fail')

    time.sleep(10)


options = webdriver.ChromeOptions()
# If options.headless = True, the website will not load
options.headless = False
options.add_argument("--window-size=1920,1080")
options.add_experimental_option("excludeSwitches", ["enable-automation"])
options.add_experimental_option('useAutomationExtension', False)
options.add_argument('--disable-blink-features=AutomationControlled')
options.add_argument('user-agent=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36')

browser = webdriver.Chrome(options = options)

browser.execute_cdp_cmd('Page.addScriptToEvaluateOnNewDocument', {
    "source": '''
    Object.defineProperty(navigator, 'webdriver', {
        get: () => undefined
    });
    Object.defineProperty(navigator, 'plugins', {
            get: function() { return {"0":{"0":{}},"1":{"0":{}},"2":{"0":{},"1":{}}}; }
    });
    Object.defineProperty(navigator, 'languages', {
        get: () => ["en-US", "en"]
    });
    Object.defineProperty(navigator, 'mimeTypes', {
        get: function() { return {"0":{},"1":{},"2":{},"3":{}}; }
    });

    window.screenY=23;
    window.screenTop=23;
    window.outerWidth=1337;
    window.outerHeight=825;
    window.chrome =
    {
      app: {
        isInstalled: false,
      },
      webstore: {
        onInstallStageChanged: {},
        onDownloadProgress: {},
      },
      runtime: {
        PlatformOs: {
          MAC: 'mac',
          WIN: 'win',
          ANDROID: 'android',
          CROS: 'cros',
          LINUX: 'linux',
          OPENBSD: 'openbsd',
        },
        PlatformArch: {
          ARM: 'arm',
          X86_32: 'x86-32',
          X86_64: 'x86-64',
        },
        PlatformNaclArch: {
          ARM: 'arm',
          X86_32: 'x86-32',
          X86_64: 'x86-64',
        },
        RequestUpdateCheckStatus: {
          THROTTLED: 'throttled',
          NO_UPDATE: 'no_update',
          UPDATE_AVAILABLE: 'update_available',
        },
        OnInstalledReason: {
          INSTALL: 'install',
          UPDATE: 'update',
          CHROME_UPDATE: 'chrome_update',
          SHARED_MODULE_UPDATE: 'shared_module_update',
        },
        OnRestartRequiredReason: {
          APP_UPDATE: 'app_update',
          OS_UPDATE: 'os_update',
          PERIODIC: 'periodic',
        },
      },
    };
    window.navigator.chrome =
    {
      app: {
        isInstalled: false,
      },
      webstore: {
        onInstallStageChanged: {},
        onDownloadProgress: {},
      },
      runtime: {
        PlatformOs: {
          MAC: 'mac',
          WIN: 'win',
          ANDROID: 'android',
          CROS: 'cros',
          LINUX: 'linux',
          OPENBSD: 'openbsd',
        },
        PlatformArch: {
          ARM: 'arm',
          X86_32: 'x86-32',
          X86_64: 'x86-64',
        },
        PlatformNaclArch: {
          ARM: 'arm',
          X86_32: 'x86-32',
          X86_64: 'x86-64',
        },
        RequestUpdateCheckStatus: {
          THROTTLED: 'throttled',
          NO_UPDATE: 'no_update',
          UPDATE_AVAILABLE: 'update_available',
        },
        OnInstalledReason: {
          INSTALL: 'install',
          UPDATE: 'update',
          CHROME_UPDATE: 'chrome_update',
          SHARED_MODULE_UPDATE: 'shared_module_update',
        },
        OnRestartRequiredReason: {
          APP_UPDATE: 'app_update',
          OS_UPDATE: 'os_update',
          PERIODIC: 'periodic',
        },
      },
    };
    ['height', 'width'].forEach(property => {
        const imageDescriptor = Object.getOwnPropertyDescriptor(HTMLImageElement.prototype, property);

        // redefine the property with a patched descriptor
        Object.defineProperty(HTMLImageElement.prototype, property, {
            ...imageDescriptor,
            get: function() {
                // return an arbitrary non-zero dimension if the image failed to load
            if (this.complete && this.naturalHeight == 0) {
                return 20;
            }
                return imageDescriptor.get.apply(this);
            },
        });
    });

    const getParameter = WebGLRenderingContext.getParameter;
    WebGLRenderingContext.prototype.getParameter = function(parameter) {
        if (parameter === 37445) {
            return 'Intel Open Source Technology Center';
        }
        if (parameter === 37446) {
            return 'Mesa DRI Intel(R) Ivybridge Mobile ';
        }

        return getParameter(parameter);
    };

    const elementDescriptor = Object.getOwnPropertyDescriptor(HTMLElement.prototype, 'offsetHeight');

    Object.defineProperty(HTMLDivElement.prototype, 'offsetHeight', {
        ...elementDescriptor,
        get: function() {
            if (this.id === 'modernizr') {
            return 1;
            }
            return elementDescriptor.get.apply(this);
        },
    });
    '''
})

visit_website(browser)

browser.quit()