Behind enemy lines in our war against account hijackers

A recent poll in the U.S. showed that more people are concerned about being hacked than having their house robbed. That’s why we continue to work hard to keep Google accounts secure. Our defenses keep most bad actors out, and we’ve reduced hijackings by more than 99% over the last few years.

We monitor many potential threats, from mass hijackings (typically used to send lots of spam) to state-sponsored attacks (highly targeted, often with political motivations).

This week, we’re releasing a study of another kind of threat we’ve dubbed “manual hijacking,” in which professional attackers spend considerable time exploiting a single victim’s account, often causing financial losses. Even though they’re rare—9 incidents per million users per day—they’re often severe, and studying this type of hijacker has helped us improve our defenses against all types of hijacking.

Manual hijackers often get into accounts through phishing: sending deceptive messages meant to trick you into handing over your username, password, and other personal info. For this study, we analyzed several sources of phishing messages and websites, observing both how hijackers operate and what sensitive information they seek out once they gain control of an account. Here are some of our findings:

• Simple but dangerous: Most of us think we’re too smart to fall for phishing, but our research found some fake websites worked a whopping 45% of the time. On average, people visiting the fake pages submitted their info 14% of the time, and even the most obviously fake sites still managed to deceive 3% of people. Considering that an attacker can send out millions of messages, these success rates are nothing to sneeze at.

• Quick and thorough: Around 20% of hijacked accounts are accessed within 30 minutes of a hacker obtaining the login info. Once they’ve broken into an account they want to exploit, hijackers spend more than 20 minutes inside, often changing the password to lock out the true owner, searching for other account details (like your bank, or social media accounts), and scamming new victims.

• Personalized and targeted: Hijackers then send phishing emails from the victim’s account to everyone in his or her address book. Since your friends and family think the email comes from you, these emails can be very effective. People in the contact list of hijacked accounts are 36 times more likely to be hijacked themselves. 

• Learning fast: Hijackers quickly change their tactics to adapt to new security measures. For example, after we started asking people to answer questions (like “which city do you login from most often?”) when logging in from a suspicious location or device, hijackers almost immediately started phishing for the answers.

We’ve used the findings from this study, along with our ongoing research efforts, to improve the many account security systems we have in place. But we can use your help too.

• Stay vigilant: Gmail blocks the vast majority of spam and phishing emails, but be wary of messages asking for login information or other personal data. Never reply to these messages; instead, report them to us. When in doubt, visit websites directly (not through a link in an email) to review or update account information.

• Get your account back fast: If your account is ever at risk, it’s important that we have a way to get in touch with you and confirm your ownership. That’s why we strongly recommend you provide a backup phone number or a secondary email address (but make sure that email account uses a strong password and is kept up to date so it’s not released due to inactivity).

• 2-step verification: Our free 2-step verification service provides an extra layer of security against all types of account hijacking. In addition to your password, you’ll use your phone to prove you’re really you. We also recently added an option to log in with a physical USB device.

Take a few minutes and visit the Secure Your Account page, where you can make sure we’ve got backup contact info for you and confirm that your other security settings are up to date.

Posted by Elie Bursztein, Anti-Abuse Research Lead

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