Google has stepped up its warning system for dubious websites: Chrome will now flag up sites that contain potentially harmful downloads, even if the site itself does no damage.

Until now Google’s warnings had only taken effect in two situations: when a Chrome user clicked on a link to a page believed to contain malware (which could cause problems simply by visiting the site) and when a user tried to download a file that could cause problems (often an executable disguised as something else.)

From now on Chrome’s SafeBrowsing feature will display a warning when the page is safe but contains an option to download a risky file. In other words, the warning appears two clicks before the dodgy download rather than the current one click.

The changes don’t just affect Chrome users. Google’s search rankings will be adjusted to downgrade sites housing the risky download links. Google is also blocking Google ads that link to such sites.

If you do run a website and aren’t currently registered on the Google Webmaster Tools service, it’s a good time to do so. Google says it will use the service to notify the people behind any site that gets hit by the new measures, allowing them to either remove the dodgy download or report it as a false positive.

ComputerWorld’s Gregg Keizer makes the valid point that this isn’t simply Google acting out of public spirit, but rather that it has a financial interest in making sure user home pages aren’t switched away from Google.com without their knowledge, and that Google’s ads don’t get associated with links to potentially harmful sites, which could make it more likely people switch on adblockers.