Selenium webdriver: Modifying navigator.webdriver flag to prevent selenium detection

Ajanth :

I'm trying to automate a very basic task in a website using selenium and chrome but somehow the website detects when chrome is driven by selenium and blocks every request. I suspect that the website is relying on an exposed DOM variable like this one https://stackoverflow.com/a/41904453/648236 to detect selenium driven browser.

My question is, is there a way I can make the navigator.webdriver flag false? I am willing to go so far as to try and recompile the selenium source after making modifications, but I cannot seem to find the NavigatorAutomationInformation source anywhere in the repository https://github.com/SeleniumHQ/selenium

Any help is much appreciated

P.S: I also tried the following from https://w3c.github.io/webdriver/#interface

Object.defineProperty(navigator, 'webdriver', {
    get: () => false,
  });

But it only updates the property after the initial page load. I think the site detects the variable before my script is executed.

DebanjanB :

First the update ¹

execute_cdp_cmd():With the availability of execute_cdp_cmd(cmd, cmd_args) command now you can easily execute google-chrome-devtools commands using Selenium. Using this feature you can modify the navigator.webdriver easily to prevent Selenium from getting detected.

---

Preventing Detection ²

To prevent Selenium driven WebDriver getting detected a niche approach would include either/all of the below mentioned steps:

• Rotating the user-agent through execute_cdp_cmd() command as follows:

  driver.execute_cdp_cmd("Network.setExtraHTTPHeaders", {"headers": {"User-Agent": "browserClientA"}})
  

• Change the property value of the navigator for webdriver to undefined

  driver.execute_cdp_cmd("Page.addScriptToEvaluateOnNewDocument", {
    "source": """
      Object.defineProperty(navigator, 'webdriver', {
        get: () => undefined
      })
    """
  })
  

• Exclude the collection of enable-automation switches

  options.add_experimental_option("excludeSwitches", ["enable-automation"])
  

• Turn-off useAutomationExtension

  options.add_experimental_option('useAutomationExtension', False)
  

---

Sample Code ³

Clubbing up all the steps mentioned above and effective code block will be:

from selenium import webdriver

options = webdriver.ChromeOptions() 
options.add_argument("start-maximized")
options.add_experimental_option("excludeSwitches", ["enable-automation"])
options.add_experimental_option('useAutomationExtension', False)
driver = webdriver.Chrome(options=options, executable_path=r'C:\WebDrivers\chromedriver.exe')
driver.execute_cdp_cmd("Page.addScriptToEvaluateOnNewDocument", {
  "source": """
    Object.defineProperty(navigator, 'webdriver', {
      get: () => undefined
    })
  """
})
driver.execute_cdp_cmd("Network.enable", {})
driver.execute_cdp_cmd("Network.setExtraHTTPHeaders", {"headers": {"User-Agent": "browser1"}})
driver.get("https://www.google.com/")

---

History

As per the W3C Editor's Draft the current implementation strictly mentions:

The webdriver-active flag is set to true when the user agent is under remote control which is initially set to false.

Further,

Navigator includes NavigatorAutomationInformation;

It is to be noted that:

The NavigatorAutomationInformation interface should not be exposed on WorkerNavigator.

The NavigatorAutomationInformation interface is defined as:

interface mixin NavigatorAutomationInformation {
    readonly attribute boolean webdriver;
};

which returns true if webdriver-active flag is set, false otherwise.

Finally, the navigator.webdriver defines a standard way for co-operating user agents to inform the document that it is controlled by WebDriver, so that alternate code paths can be triggered during automation.

Caution: Altering/tweaking the above mentioned parameters may block the navigation and get the WebDriver instance detected.

---

Update (6-Nov-2019)

As of the current implementation an ideal way to access a web page without getting detected would be to use the ChromeOptions() class to add a couple of arguments to:

• Exclude the collection of enable-automation switches
• Turn-off useAutomationExtension

through an instance of ChromeOptions as follows:

• Java Example:

  System.setProperty("webdriver.chrome.driver", "C:\\Utility\\BrowserDrivers\\chromedriver.exe");
  ChromeOptions options = new ChromeOptions();
  options.setExperimentalOption("excludeSwitches", Collections.singletonList("enable-automation"));
  options.setExperimentalOption("useAutomationExtension", false);
  WebDriver driver =  new ChromeDriver(options);
  driver.get("https://www.google.com/");
  

• Python Example

  from selenium import webdriver
  
  options = webdriver.ChromeOptions()
  options.add_experimental_option("excludeSwitches", ["enable-automation"])
  options.add_experimental_option('useAutomationExtension', False)
  driver = webdriver.Chrome(options=options, executable_path=r'C:\path\to\chromedriver.exe')
  driver.get("https://www.google.com/")
  

---

Legends

¹: Applies to Selenium's Python clients only.

²: Applies to Selenium's Python clients only.

³: Applies to Selenium's Python clients only.