Microsoft phishing attacks have targeted more than 10,000 organizations starting with September 2021, using the gained access to victims’ mailboxes in follow-on business email compromise (BEC) attacks.
The threat actors used landing pages designed to hijack the Office 365 authentication process (even on accounts protected by multifactor authentication (MFA) by spoofing the Office online authentication page.
In some of the observed attacks, the potential victims were redirected to the landing pages from phishing emails using HTML attachments that acted as gatekeepers ensuring the targets were being sent via the HTML redirectors.
After stealing the targets’ credentials and their session cookies, the threat actors behind these attacks logged into the victims’ email accounts. They subsequently used their access in business email compromise (BRC) campaigns targeting other organizations.
