Can Websites Detect Selenium with Chromedriver?

It may be surprising to discover that some websites can identify when you're using Selenium with Chromedriver, even if you're not actively automated. This is attributed to the fact that these websites employ bot detection scripts.

How do Websites Detect Selenium?

Bot detection scripts inspect predefined JavaScript variables that emerge when Selenium is employed. They search for declarations containing "selenium" or "webdriver" in window objects or document variables like $cdc_ and $wdc_.

Methods to Evade Detection

To avoid detection, you can remove these telltale variables. In the case of Chrome, removing $cdc_ is sufficient. This adjustment can be made to the chromedriver source code.

Bot Detection Pseudocode

Bot networks use a range of techniques to detect automation, such as:

• Checking window and document objects for specific detection keys (e.g., __webdriver_evaluate)
• Identifying variables including $cdc_ that are associated with Selenium
• Examining event listeners for patterns indicative of automated behavior

Conclusion

While Chromedriver and Chrome might seem identical to web servers, sophisticated detection methods employed by websites can uncover the presence of Selenium. By removing telltale variables or employing advanced techniques, you can attempt to evade detection when using Selenium for testing or other purposes.