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Phishing lures sent as ICS calendar invites land in Outlook and Gmail calendars without a click and stay after the email is deleted; EvilTokens used them for Microsoft 365 device-code phishing

Netcraft reports that attackers send phishing lures as ICS calendar files because the "text/calendar" type is treated as low risk by major email clients, and that the mail client's normal invite handling then places the lure in the victim's calendar with no user interaction, often keeping it there after the original email is deleted (Netcraft, 2026-10-16). In Netcraft's client table, Outlook desktop, Outlook on the web and Outlook Mobile with Exchange Online and Gmail with Google Calendar add the event automatically, mark it tentative and keep it after the email is deleted, Apple Calendar connected to Exchange Online often does the same, and Apple Mail with iCloud does not add it (Netcraft, 2026-10-16).

Campaigns using the EvilTokens toolkit, which steals Microsoft 365 tokens, used ICS invites disguised as meetings, alerts or voicemail notifications; the link leads to a page that gives the user a device code and tells them to enter it on Microsoft's device authorization page, which grants an attacker's device access to the account through OAuth (Netcraft, 2026-10-16). Netcraft now also sees smaller scams carrying ordinary phishing content inside ICS files (Netcraft, 2026-10-16). Sublime Security reports "exponential growth" in calendar phishing, with lures such as voicemail notices, payment receipts and renewal warnings that link to fake Microsoft, Google or PayPal logins or give a phone number, and Cofense says some senders use legitimate platforms such as Zoom to send the invitations, so filtering those platforms would also block real meetings (The Guardian, 2026-10-11).

Builds on: Huntress: device-code phishing and ROPC token-spray defeat M365 tenants by routing around the…

Three Russia-nexus espionage clusters compromise European diplomats and academics without malware, by talking targets through app passwords, device-code approvals and WhatsApp device-linking, all of which are legitimate features working as designed

Google Threat Intelligence Group published research on 2026-08-20 covering three suspected Russia-nexus espionage clusters that share a method rather than infrastructure: they compromise accounts by driving legitimate authentication features, not by delivering malware (Google Threat Intelligence Group, 2026-08-20). The reported target set puts this constituency inside the blast radius directly, "individuals working in academia, aerospace and defense, governments and think tanks across Europe", alongside US academia and think tanks. GTIG assesses with high confidence that all three possess a Russian nexus, and with moderate confidence that two of them are sub-clusters of the actor it tracks as ICE RELIC (the cluster more widely known as Midnight Blizzard) handling initial access.

Application passwords (UNC6293). An application-specific password is an account-level passcode issued so that a legacy client can authenticate without going through the second factor. The cluster sends a diplomatic or conference-themed lure, a PDF containing screenshots that walk the target through creating a password under a specific, official-looking name and sharing it back. Nothing is exploited and no code runs; the victim performs the whole operation, and the resulting credential is designed not to prompt for a second factor. Campaigns are deliberately small, typically fewer than five targets at a time. By mid-2026 the cluster had added a variation asking targets to share a verification code or post-login URL after authenticating legitimately to an external provider.

Device codes and WhatsApp linking (UNC7005, tracked here as Storm-2945, the cluster behind the CaptiveCrunch hospitality-WiFi captive-portal activity). The device-code flow exists so that input-constrained devices can authenticate: one device shows a short code, the user approves it on another. Phished, it becomes a way to have the victim authorise the attacker's session. This cluster delivers those prompts through emailed links to domains impersonating real conferences (GTIG documents a spoof of a European security forum reusing a template from an earlier embassy-invitation operation) and the pages fingerprint the browser with client-side JavaScript to detect automated scanners and headless browsers, withholding the code entirely until the visitor looks like a real person. That last detail matters operationally: a security team detonating the link in a sandbox may see a benign page.

The WhatsApp technique is the same idea applied to a messaging platform. The page asks for the target's phone number, the attacker's backend uses it to generate a genuine device-linking request, and the resulting code is displayed to the victim with instructions to approve it, linking the attacker's device to the victim's account through the vendor's own supported mechanism. The page then offers a voice call, encrypted chat or file share; if the victim joins the call, browser JavaScript captures microphone and camera through the standard media-capture interface and uploads the recording while the call is presented as having failed.

OAuth token harvesting (UNC5976). Assessed as operationally distinct from the other two, this cluster buys file-sharing-themed domains, creates a cloud project for each, and serves a fake file-share login. A target choosing to continue with their existing identity provider is sent through a genuine consent flow and then redirected to the attacker's own cloud-project URL, where a script captures the resulting token. GTIG disrupted the operation by disabling the malicious cloud projects; the cluster stood up at least twelve new domains within roughly three months and began moving hosting elsewhere. It has separately distributed a malicious spreadsheet plugin GTIG names HEADRUSH, observed in April 2026 and leading to an HTML Application downloader (a scripted payload executed through the built-in Windows host binary rather than as a conventional executable) delivered through a domain impersonating a Ukrainian research institute.

Detection concepts, telemetry class first. The unifying property is that none of this produces endpoint malware telemetry on the way in, the compromise completes in the identity plane, so that is where it must be caught. In identity and sign-in telemetry: creation of an application-specific password, which for most organisations should be a rare or extinct event and is trivially alertable; completion of a device-code authorisation, particularly where the approving session and the resulting access originate from different networks or geographies; and new OAuth consent grants to applications outside an approved inventory. In mail and web telemetry, conference-themed invitations linking to newly registered lookalike domains are the delivery pattern, though the browser fingerprinting means automated detonation may return a clean verdict, treat a link that renders differently for a sandbox than for a user as suspicious in itself rather than as a false positive. On the messaging side, the observable is the account's own linked-device list, which is user-visible and rarely inspected.