Final update If you get an email today sharing a Google Docs file with you, don't click it – you may accidentally hand over your Gmail inbox and your contacts to a mystery attacker.
The phishing campaign really kicked off in a big way on Wednesday morning, US West Coast time. The malicious email contains what appears to be a link to a Google Doc file. This leads to a legit Google.com page asking you to authorize "Google Docs" to access to your Gmail account.
Except it's not actually the official Google Docs requesting access: it's a rogue web app with the same name that, if given the green light by unsuspecting marks, then ransacks contact lists and sends out more spam. It also gains control over the webmail account, including the ability to read victims' messages and send new ones on their behalf.
Apparently no one at Google thought to block someone calling their app Google Docs.
If the permissions are granted, the software will immediately spam out the same message to all the people on your contacts list, bypassing two-factor authentication if you have that set up on your account. Here at Vulture West we've been getting bombarded with these emails, including some from journalists at other publications.
"There's a very clever phishing scam going around at the moment – originally thought to be targeting journalists given the sheer number of them mentioning it on their Twitter feeds, it's also been slinging its way across unrelated mailboxes – from orgs to schools / campuses," explained Christopher Boyd, malware intelligence analyst at Malwarebytes, today.
"This doesn't mean it didn't begin with a popped journo mailbox and spread its way out from there, or that someone didn't intentionally send it to a number of journalists of course – but either way, this one has gone viral and not in a 'look at the cute cat pic' fashion."
The emails do have some distinguishing characteristics. They are all addressed to the same email@example.com address, with the victims BCC'd, and sent from the last person to accidentally authorize the malicious app.
If you have fallen prey to the attack, there are steps that can be taken to ameliorate the situation. Simply go into your Google account permissions page and remove all the access privileges for the evil Google Docs account.
Google hasn't released an official statement, however its Project Zero wunderkind Tavis Ormandy has confirmed that the security team is on the case. Gmail has also said it is aware of the issue.
It doesn't appear at this point that there's a malware payload included with the messages, but it's very early days yet. What is clear is that this messages are spreading like wildfire and the attackers are going to be harvesting email lists for future attacks – so let's be careful out there.
For what it's worth, the servers hosting the malicious app appear to be down at time of writing. Reg hacks who received the messages had to fish the phishes out of their spam folders. ®
Updated to add
Google has now issued a statement on the attack, saying it has locked down its systems to prevent any further spread of the emails.
"We have taken action to protect users against an email impersonating Google Docs, and have disabled offending accounts," said a spokesperson in an email.
"We’ve removed the fake pages, pushed updates through Safe Browsing, and our abuse team is working to prevent this kind of spoofing from happening again. We encourage users to report phishing emails in Gmail."
Cooper Quintin, staff technologist at the EFF, told The Register that he has now collected over 400 samples of the emails and it doesn't appear to be carrying a malware payload. The attack bears some similarities to a nation-state attack earlier this year but he said that, in his opinion, this case was too noisy to be state actors.
"Nation state attacks prefer to stay under the radar," he explained. "It was a hell of an attack, but may have been too successful for its own good."
In the best case scenario the attackers would just have gained a shed-load of valid email addresses and a good idea of who is likely to click on such links. But, Cooper pointed out, the attacker would also have been able to scan emails for useful snippets of data for other attacks.
A Google spokesperson has got back to us with some more info:
We realize people are concerned about their Google accounts, and we're now able to give a fuller explanation after further investigation. We have taken action to protect users against an email spam campaign impersonating Google Docs, which affected fewer than 0.1% of Gmail users.
We protected users from this attack through a combination of automatic and manual actions, including removing the fake pages and applications, and pushing updates through Safe Browsing, Gmail, and other anti-abuse systems. We were able to stop the campaign within approximately one hour. While contact information was accessed and used by the campaign, our investigations show that no other data was exposed. There’s no further action users need to take regarding this event; users who want to review third party apps connected to their account can visit Google Security Checkup.
So, based on that statement, and given that more than a billion people use Gmail now, potentially more than a million Gmail users had their contact lists ransacked today.