A very clever and convincing series of ongoing phishing attacks uses fake Office 365 notifications that ask potential victims to check blocked spam messages with the aim of stealing their Microsoft credentials.

These phishing emails are very convincing because they use quarantine[at]messaging.microsoft.com to send them to potential victims, and the display name, which also matches the domains of the recipients.

The attackers have also embedded the official Office 365 logo as well as links to Microsoft’s privacy policy and acceptable terms of use at the end of the email.

However, the phishing messages contain text formatting problems and misplaced additional spaces that would allow a vigilant user to see the maliciousness of these emails on closer inspection.

“The email subject is ‘Spam Notification: 1 New Messages,’ which refers to the body of the email that tells the recipient that a spam message has been blocked and is quarantined for review,” said cloud email security provider MailGuard, which discovered this phishing campaign.

“Details of the ‘Prevented spam message’ are provided, with scammers personalizing the subject heading as ‘[company domain] Adjustment: Transaction Expenses Q3 UPDATE’ so as to send a sense of urgency and employing a finance-related message.”

Targets are given 30 days to verify the quarantine messages by going to the Microsoft Security and Compliance Center and clicking on an embedded link.

If you click on the embedded link, the target will be taken to a phishing landing page that asks for Microsoft credentials to access the quarantined spam messages.

As soon as the target people enter their login credentials in the malicious form on the phishing page, the data of their accounts is automatically sent to servers controlled by attackers.

Once the victims’ Microsoft credentials have been stolen, they can later be used by cyber criminals to control their accounts and access their private information.

Successful phishing attacks lead to identity theft and fraud attempts, as well as Business Email Compromise (BEC) attacks.

The US Federal Trade Commission (FTC) recently revealed that the number of identity theft complaints doubled in 2020 compared to 2019, to 1.4 million.