New Phishing Attack Creates Malicious Pages Inside the Victim’s Browser

Barracuda details a phishing campaign that renders pages in-browser via blob URLs, routed through Microsoft Teams and cdn.bloom[.]io to evade detection.

Barracuda researchers analyzed a phishing campaign that generates a blob URL to render the phishing page entirely inside the victim's browser, leaving no static page for scanners to inspect. The chain begins with a Docusign-themed email containing a calendar invite, followed by a crafted redirect through Microsoft Teams to a resource on cdn.bloom[.]io that the browser converts into the blob URL. Service workers, iframes, and a hidden command-and-control configuration indicate the page is part of a centrally managed phishing platform that can be updated and steered across victims. Researchers recommend inspecting blob URL activity, monitoring OAuth authorization flows, and analyzing the full click path in email security controls.