New Research: Lessons from Password Checkup in action

Posted by Jennifer Pullman, Kurt Thomas, and Elie Bursztein, Spam and Abuse research

Back in February, we announced the Password Checkup extension for Chrome to help keep all your online accounts safe from hijacking. The extension displays a warning whenever you sign in to a site using one of over 4 billion usernames and passwords that Google knows to be unsafe due to a third-party data breach. Since our launch, over 650,000 people have participated in our early experiment. In the first month alone, we scanned 21 million usernames and passwords and flagged over 316,000 as unsafe---1.5% of sign-ins scanned by the extension.

Today, we are sharing our most recent lessons from the launch and announcing an updated set of features for the Password Checkup extension. Our full research study, available here, will be presented this week as part of the USENIX Security Symposium.

Which accounts are most at risk?

Hijackers routinely attempt to sign in to sites across the web with every credential exposed by a third-party breach. If you use strong, unique passwords for all your accounts, this risk disappears. Based on anonymous telemetry reported by the Password Checkup extension, we found that users reused breached, unsafe credentials for some of their most sensitive financial, government, and email accounts. This risk was even more prevalent on shopping sites (where users may save credit card details), news, and entertainment sites.

In fact, outside the most popular web sites, users are 2.5X more likely to reuse vulnerable passwords, putting their account at risk of hijacking.

Anonymous telemetry reported by Password Checkup extension shows that users most often reuse vulnerable passwords on shopping, news, and entertainment sites.

Helping users re-secure their unsafe passwords

Our research shows that users opt to reset 26% of the unsafe passwords flagged by the Password Checkup extension. Even better, 60% of new passwords are secure against guessing attacks—meaning it would take an attacker over a hundred million guesses before identifying the new password.

Improving the Password Checkup extension

Today, we are also releasing two new features for the Password Checkup extension. The first is a direct feedback mechanism where users can inform us about any issues that they are facing via a quick comment box. The second gives users even more control over their data. It allows users to opt-out of the anonymous telemetry that the extension reports, including the number of lookups that surface an unsafe credential, whether an alert leads to a password change, and the domain involved for improving site coverage. By design, the Password Checkup extension ensures that Google never learns your username or password, regardless of whether you enable telemetry, but we still want to provide this option if users would prefer not to share this information.


We're continuing to improve the Password Checkup extension and exploring ways to implement its technology into Google products. For help keeping all your online accounts safe from hijacking, you can install the Password Checkup extension here today.