A new callback phishing campaign has been detected that uses Google Forms to add credibility to the campaign. Callback phishing involves sending an email and tricking the recipient into calling a customer service helpline, where they are convinced to download software that provides the attacker with remote access to their device. Since the emails contain no malicious content, only a phone number, these emails are usually delivered to inboxes.

A typical campaign involves an email about an impending charge for a subscription for software or a service, payment for which is about to be taken shortly. The user is told that they must respond within 24 hours if they have any dispute and that the subscription will auto-renew if no action is taken. Companies typically impersonated in these attacks include Netflix, Hulu, Disney+, Masterclass, McAfee, Norton, and GeekSquad.

The impending charge is excessive, typically $50 to $500, and the only way to prevent the payment is to call the customer service number included in the email. Subscriptions for software, streaming platforms, and other services are often set to auto-renew by default, and many people end up paying for another term even if they have discontinued using that service. The lure is therefore plausible, and since the charge is excessive, the recipient is likely to make the call.

The phone number is manned by the threat actor who pretends to be customer support and helps the user block the charge; however, in order to do so, software must be downloaded onto the user’s device. The user is convinced to install the software, the threat actor appears to remove the offending software, and the payment issue is resolved; however, the threat actor has installed malware that provides access to the user’s device.

In late 2020/ early 2021, this method was used in BazarCall attacks, so named because they were conducted to deliver BazarLoader malware. The malware is used to download additional malware payloads to the user’s device, such as ransomware. A new version of this campaign has recently been detected that employs Google Forms to add legitimacy to the campaign. Google Forms is free to use and allows forms to be easily created for surveys and quizzes, which can be integrated with websites or shared. In the latest BazarCall campaign, Google Forms is used to create details of a fake transaction, complete with invoice number, payment method, payment date, and information about the product or service.

Google Forms includes the option for a response receipt in the settings, so when a form is completed, it is submitted to the entered email address – that of the target. Google sends the completed form from its own servers, which adds legitimacy to the campaign and increases the probability of the form reaching an inbox. Email security solutions trust the sender (noreply@google.com) and the messages contain no malware or phishing links, the email is guaranteed to be delivered. The form instructs the recipient to call the number within 24 hours if they have any dispute about the charge.

Google is aware of the campaign and is taking steps to improve detection and said that the campaign has so far been used for a small number of users; however, it is worthwhile updating your security awareness training to include this new method of attack. That is quick and easy to do and roll out with the SafeTitan security awareness training platform. SafeTitan also allows you to easily add this method of phishing to the phishing simulator, to see if your employees are likely to fall for callback phishing scams.