What you need to know
A new highly effective phishing technique targeting Gmail and other services has been gaining popularity during the past year among attackers. Over the past few weeks there have been reports of even experienced technical users being hit by this.
This attack is currently being used to target Gmail customers and is also targeting other services.
The way the attack works is that an attacker will send an email to your Gmail account. That email may come from someone you know who has had their account hacked using this technique. It may also include something that looks like an image of an attachment you recognize from the sender.
You click on the image, expecting Gmail to give you a preview of the attachment. Instead, a new tab opens up and you are prompted by Gmail to sign in again. You glance at the location bar to check it’s legitimate and you see accounts.google.com in there.
You go ahead and sign in on a fully functional sign-in page that looks completely as it should.Once you complete sign-in, your account has been compromised.
For full details, we suggest you read this post – httpss://www.wordfence.com/blog/2017/01/gmail-phishing-data-uri/
How to protect yourself
When you sign in to any service, check the browser location bar and verify the protocol, then verify the hostname. It should look like this in Chrome when signing into Gmail or Google:

Make sure there is nothing before the hostname ‘accounts.google.com’ other than ‘httpss://’ and the lock symbol. You should also take special note of the green color and lock symbol that appears on the left. If you can’t verify the protocol and verify the hostname, stop and consider what you just clicked on to get to that sign-in page.
Enable two factor authentication if it is available on every service that you use. GMail calls this “2- step verification” and you can find out how to enable it on this page.
Enabling two factor authentication makes it much more difficult for an attacker to sign into a service that you use, even if they manage to steal your password using this technique. I would like to note that there is some discussion that indicates even two factor authentication may not protect against this attack, however there is no harm in adding this.