All Gmail users are being urged to stay on high alert and watch out for a worrying new ‘attack’. With billions of people across the planet using this Google-owned platform, it’s no surprise that it’s a top target for cyber crooks. Luckily, thanks to some pretty efficient security, the majority of fake and hoax messages get caught and filtered straight into the spam folder.

However, it seems criminals have now found a way to avoid being spotted, and that means dangerous emails aren't getting blocked and are landing in inboxes.

The new alert has been raised by developer Nick Johnson. He says he was recently targeted by an "extremely sophisticated" phishing attack which uses a new technique to avoid being spammed.

The email message - which featured official Google branding and font - warned that a legal subpoena had been issued and a copy of his Google account content was needed by law enforcement.

Of course, this might instantly sound like a scam, but what made things most concerning is that the sender’s email address was a valid Google account. This means it appears to have been sent by the US tech firm and not a cyber crook. Checking the sender's email address is usually a telltale sign that things are fake, but this new type of attack is able to trick the system.

"The first thing to note is that this is a valid, signed email - it really was sent from no-reply@google.com. It passes the DKIM signature check, and GMail displays it without any warnings," Johnson explained.

Google's DKIM signature check would usually filter all suspicious emails and place them straight in the spam folder. This scary attack is able to con people by generating a real Google domain.

Anyone now getting a similar message in their inbox needs to be alert as it contains dangerous links that could hand personal data over to hackers.

Luckily, Google is now rushing to release a fix that will stop its name and email address from being used to attack Gmail account holders in the future.

"We're aware of this class of targeted attack from the threat actor, Rockfoils, and have been rolling out protections for the past week," a Google spokesperson told Newsweek.

"These protections will soon be fully deployed, which will shut down this avenue for abuse."

There's no word on how long it will take Google to release this update globally so, for now, anyone with a Gmail account needs to remain alert.