Alphabet Inc has warned users to beware of emails from contacts asking them to click on a Google Docs link after a large number of people complained on social media that their accounts had been hacked.
"We are investigating a phishing email that appears as Google Docs," the company tweeted from its Google Docs account on Wednesday.
"We encourage you to not click through and report as phishing within Gmail."
The scam asks people to click on a link to view a document, which provides hackers access to the contents of their Google accounts, including email, contacts and online documents, security experts said.
"This is a very serious situation for anybody who is infected because the victims have their accounts controlled by a malicious party," cyber security professor at NYU Tandon School of Engineering, Justin Cappos, said.
Cappos said he received seven malicious emails in three hours on Wednesday, an indication hackers were using an automated system to attack.
He said he did not know the objective but noted compromised accounts could be used to reset passwords for online banking accounts or provide access to sensitive financial and personal data.
Google did not respond for requests to comment beyond its tweet.
Other security experts said victims should remove the hackers from their accounts as soon as possible.
"The point of the attack isn't clear yet but it could be a pre-cursor to some larger attack they're planning," Matthew Gardiner, a security expert with email security firm Mimecast, said.
