Can Websites Detect Selenium Even Without Explicit Automation?

Deciphering Selenium Detection Techniques

Can a website indeed detect Selenium usage even when no automation is involved? This persistent issue puzzles users who question how web servers pinpoint the presence of Selenium, despite the expectation that Selenium and Chrome should appear indistinguishable to them.

As it turns out, bot detection scripts exploit predefined JavaScript variables that reveal Selenium's presence. These variables, imbued with names like "selenium" or "webdriver," serve as telltale signs in various browser environments.

To circumvent this detection, developers can adopt various tactics. One ingenious approach involved modifying the Chromedriver source code, particularly the "getPageCache" function, and replacing the infamous "$cdc_" variable with an innocuous alternative. This subtle change thwarted bot networks from identifying Selenium's presence.

Beyond this specific method, bot networks employ an array of sophisticated techniques to unmask Selenium. They scour browser environments for suspicious variables, whether in the "window" or "document" objects. By matching known patterns, these algorithms expose Selenium's presence with alarming accuracy.

Examples of these patterns include:

• Window Variables: "_phantom", "callSelenium", "__webdriver_unwrapped"
• Document Variables: "__webdriver_evaluate", "document.documentElement.getAttribute("selenium")"

To evade detection, developers can adopt countermeasures such as replacing or sanitizing suspicious variables or incorporating browser extensions that disguise Selenium's footprint. The battle between bot networks and Selenium users continues to evolve, with both sides developing increasingly clever detection and evasion tactics.

The above is the detailed content of Can Websites Detect Selenium Even Without Explicit Automation?. For more information, please follow other related articles on the PHP Chinese website!