Microsoft warns of phishing campaign abusing ‘open redirects’

According to the Microsoft 365 Defender Threat Intelligence Team, attackers combine these links with social engineering baits that impersonate well-known productivity tools and services to lure users into clicking. Doing so leads to a series of redirections—including a CAPTCHA verification page that adds a sense of legitimacy and attempts to evade some automated analysis systems—before taking the user to a fake sign-in page. This ultimately leads to credential compromise, which opens the user and their organization to other attacks.

In this campaign, the team noticed that the emails seemed to follow a general pattern that displayed all the email content in a box with a large button that led to credential harvesting pages when clicked. The subject lines for the emails varied depending on the tool they impersonated. In general, Microsoft observed that the subject lines contained the recipient’s domain and a timestamp.