The Alert Method, authenticateUsing()
lets you skip the Http Basic Authentication box.
WebDriverWait wait = new WebDriverWait(driver, 10);
Alert alert = wait.until(ExpectedConditions.alertIsPresent());
alert.authenticateUsing(new UserAndPassword(username, password));
As of Selenium 3.4 it is still in beta
Right now implementation is only done for
InternetExplorerDriver