New Passkey Attacks Can Recover Synced Private Keys or Bypass Phishing
Three research teams showed passkey bypasses: WebAuthn assertion replay in Microsoft Entra ID, synced-passkey key recovery in Google Password Manager, and Windows Hello key reuse.
SpecterOps' Pass-the-Passkey research showed Windows stored past YubiKey signatures in cleartext and chained this with Microsoft Entra ID passkey validation weaknesses to impersonate privileged users despite phishing-resistant MFA; the Windows Event Logging Service issue is tracked as CVE-2026-34348 (CVSS 6.5) and fixed in July 2026 updates. Unit 42's Golden Pass-ta-key attack recovered the 32-byte Security Domain Secret protecting Google Password Manager synced passkeys from Chrome on Windows via pre-existing malware. Dirk-jan Mollema showed in-session malware can use a hardware-bound Windows Hello for Business key without a fresh PIN or biometric check. Microsoft applied Entra-side mitigations for the relay assertion issue; no real-world exploitation has been reported.
Hackers Use Blob URLs and Microsoft Teams to Create Phishing Pages Inside Victims’ Browsers
Barracuda details a phishing campaign using Microsoft Teams OAuth redirects and browser blob URLs to render local fake DocuSign login pages for credential theft.
Barracuda researchers identified an active phishing campaign that routes DocuSign-themed emails with calendar invites through a Microsoft OAuth endpoint and crafted redirects into Microsoft Teams, then renders a fake sign-in page via a browser-generated blob URL. Because the page is assembled locally in memory and can register service workers and run in a sandboxed iframe, URL-reputation checks largely see legitimate Microsoft domains. The goal is credential theft and account takeover, not a flaw in Teams itself.
New Phishing Attack Uses Blob URLs to Hide Malicious Pages From Security Scanners
Barracuda detailed a DocuSign-themed phishing campaign that renders credential-harvesting pages as browser blob URLs, evading URL reputation and blocklist defenses.
Barracuda researchers report a credential-harvesting phishing campaign that starts with a DocuSign-themed email containing a calendar invitation and routes victims through legitimate Microsoft OAuth endpoints and Microsoft Teams. A crafted redirect parameter leads Teams to load external content from cdn.bloom[.]io, which the browser renders as a blob URL — a session-only address held in local memory with no persistent public URL to crawl, categorize, or blocklist. The locally generated page registers a service worker, runs inside a sandboxed iframe, and is dynamically steered by backend infrastructure, indicating a centrally managed phishing platform. Barracuda recommends phishing-resistant MFA such as FIDO2 keys and passkeys, monitoring OAuth flows and redirect chains, and Teams malicious URL protection.
Cybercriminals are building phishing pages that exist only inside victims’ browsers
Barracuda details a DocuSign-themed phishing campaign that renders login pages locally via blob URLs, abusing genuine Microsoft OAuth and Teams infrastructure.
Barracuda researchers describe a phishing campaign that starts with DocuSign-themed emails carrying calendar invites pointing to genuine Microsoft OAuth endpoints, then routes victims through Microsoft Teams to a resource hosted on cdn.bloom[.]io. The login page is assembled entirely inside the victim's browser from a blob URL, registers a service worker, and runs inside a sandboxed iframe that receives live instructions from the attacker's backend. Hidden command-and-control configuration indicates the page is part of a centrally managed phishing platform that can be updated and steered across many victims. Barracuda recommends phishing-resistant MFA such as FIDO2 keys or passkeys, monitoring of OAuth flows and redirect chains, and behavior-based identity controls rather than URL blocklisting.