Microsoft Teams phishing campaign targeted up to 50,000 Office 365 users

Experts warn of a phishing campaign that already targeted up to 50,000 Office 365 users with a fake automated message from Microsoft Teams.

Secruity researchers reported that up to 50,000 Office 365 users have been targeted by a phishing campaign that pretends to be automated message from Microsoft Teams. The bait message uses fake notifications of a “missed chat” from Microsoft Teams, the campaigns aims at stealing Office 365 recipients’ login credentials.

Like other collaboration and communications platforms, the popularity of Microsoft Teams has risen since the beginning of the Covid-19 pandemic because a growing number of organizations started using the remote working model. Threat actors are adapting their attack techniques to exploit the ongoing situation, researchers from Abnormal Security observed campaign that hit between 15,000 to 50,000 Office 365 users.

“This attack impersonates an automated message from Microsoft Teams in order to steal recipient’s login credentials.” reads the report published by Abnormal Security. “The email is sent from the display name, ‘There’s new activity in Teams’, making it appear like an automated notification from Microsoft Teams. It appears to notify the recipient that their teammates are trying to reach them and urges the recipient to click on ‘Reply in Teams’. However, this leads to a phishing page.”

Microsoft Teams phishing campaign targeted up to 50,000 Office 365 users

The bait email displays the name “There’s new activity in Teams” to trick the victims into believing that it is an automated notification from Microsoft Teams.

The email tells the recipient that they have missed Microsoft Team chats and show an example of a teammate chat that asks them to submit something by Wednesday of next week.

The researchers that the campaing is not targeted in nature as the employee referenced in the chats doesn’t appear to be an employee of the company that was targeted by the attackers.

Recipient could respond to the email by click on the “Reply in Teams” button that is present in the content of the message, but as a consequence of this action, the victim is redirected to a phishing page.

“Within the body of the email, there are three links appearing as ‘Microsoft Teams’, ‘(contact) sent a message in instant messenger’, and ‘Reply in Teams’,” continues the analysis. “Clicking on any of these leads to a fake website that impersonates the Microsoft login page. The phishing page asks the recipient to enter their email and password.”

The phishing landing looks like a Microsoft login page, its URL begins with the “microsftteams” to appear as legitimate.

“The attacker spoofed employee emails and also impersonated Microsoft Teams. The recipient is more likely to fall prey to an attack when it is believed to originate from within the company and also from a trusted brand.” concludes the report.



Pierluigi Paganini

(SecurityAffairs – hacking, Microsoft Team)

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