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Researchers and incident responders are warning that attackers are increasingly abusing Microsoft Entra ID's OAuth 2.0 device code flow to hijack Microsoft 365 accounts through legitimate sign-in prompts rather than malware or software exploits. In these attacks, victims are tricked via vishing or phishing into entering an attacker-supplied code at Microsoft's device login page and approving MFA, which issues the attacker valid access and refresh tokens. Security firms say the technique can provide broad access to services including Microsoft Graph, Exchange Online, OneDrive, and SharePoint, and that password resets alone may not fully contain the intrusion because refresh tokens can persist across services.
The activity has been tied to data theft and follow-on abuse. ReliaQuest reported that the Helix extortion group used device code phishing, MFA abuse, and rogue authenticator registration to access victim Microsoft 365 tenants, enumerate SharePoint, and exfiltrate data before extortion; reported victims include Medtronic, Nissan, NAIC, Kodak, Infinite Campus, and the University of Nottingham. Separate investigations documented attackers signing in from foreign locations, registering multiple devices, creating hidden inbox rules to suppress replies, and using compromised mailboxes to send phishing messages at scale. Microsoft and security researchers recommend blocking or restricting device code authentication with Conditional Access, limiting SharePoint and device registration to managed devices, and monitoring Entra ID telemetry for AuthenticationProtocol set to device code, unusual travel, mailbox rule changes, and spikes in device registrations.
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Gurucul described Kali365 as a high-severity phishing-as-a-service kit targeting U.S. organizations through Microsoft device code phishing, enabling attackers to obtain OAuth access and refresh tokens for persistent Microsoft 365 access. The report also published associated domains and URLs and provided detection queries for identifying related activity.
Trend Micro reported on an investigated device-code phishing case in which an attacker gained cloud account access, later signed in from abroad, registered multiple devices, created a hidden inbox rule, and used the compromised mailbox to send phishing emails to hundreds of external recipients. The report provided identity-focused detection guidance and recommended disabling device-code flow where unnecessary.
Researchers identified a new data extortion group called Helix that steals Microsoft 365 access through social engineering methods including vishing, device code phishing, and MFA abuse rather than software exploitation. Reported victims included Medtronic, Nissan, NAIC, Kodak, Infinite Campus, and the University of Nottingham, with activity focused on SharePoint data theft and extortion.
TrustedSec published an analysis of how attackers abuse Microsoft Entra ID's OAuth 2.0 device code flow to phish users into approving legitimate sign-ins, yielding access and refresh tokens for Microsoft 365 services. The article also highlighted detection opportunities in Entra ID logs and recommended blocking device code flow with Conditional Access.
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A phishing campaign abused Microsoft's OAuth 2.0 **Device Authorization Grant** (`Device Code Flow`) to capture valid Microsoft account tokens without sending victims to a counterfeit login page. Victims received emails posing as legal notifications, including password-protected PDF attachments, and were funneled through phishing pages that displayed a one-time device code before directing them to the legitimate `microsoft.com/devicelogin` page. After victims entered the code and completed normal MFA on Microsoft's real site, the attackers obtained `access_token`, `refresh_token`, and `id_token` values tied to attacker-controlled applications. The stolen tokens enabled persistent access to Microsoft services including **email, OneDrive, and Teams**, allowing attackers to read messages, access files, and monitor conversations. Researchers said the activity was observed from early April to mid-May 2026 and included a Brazil-focused variant that used legitimate redirect links, including on **cacoo.com**, to add credibility to the lure chain. Defenders were urged to reject unexpected device authorization prompts, inspect redirect parameters in otherwise legitimate URLs, disable Device Code Flow in Microsoft Entra ID where it is not needed, and monitor **DeviceCodeSignIn** and anomalous sign-in activity for signs of compromise.
Jul 9, 2026
Attackers abused Microsoft’s OAuth 2.0 Device Authorization Grant flow to phish users into authorizing attacker-controlled sessions on legitimate Microsoft login pages, allowing them to capture **access tokens**, **refresh tokens**, and **ID tokens** without stealing passwords directly. In the observed campaign, victims received phishing emails, were routed through phishing landing pages and open redirects, and were told to enter attacker-supplied one-time device codes on Microsoft’s official device verification page before completing MFA. The stolen tokens enabled access to Microsoft 365 services including **email**, **OneDrive**, and **Teams**. Researchers also observed a Brazil-focused variant that used `cacoo.com`, a legitimate Nulab-owned service, as an open redirect to phishing infrastructure. Recommended mitigations include training users to reject unsolicited device-code requests, reviewing redirect parameters and final destinations, monitoring **DeviceCodeSignIn** events, enforcing device-compliance controls, and disabling Device Code Flow in Microsoft Entra ID where it is not required.
Jul 6, 2026
Researchers identified **EvilTokens** as a new phishing-as-a-service platform built to hijack **Microsoft 365** accounts by abusing Microsoft’s legitimate OAuth 2.0 **device code** authentication flow. Sold and operated through Telegram bots, the service gives affiliates phishing templates, email harvesting and reconnaissance features, automated Microsoft API interactions, webmail access, and mailbox triage capabilities. Victims are lured into entering attacker-supplied device codes on Microsoft’s real login page, allowing attackers to capture access and refresh tokens—and in some cases a **Primary Refresh Token**—without stealing passwords or directly defeating MFA. Security teams linked a sharp rise in device code phishing to EvilTokens, describing it as the first known turnkey PhaaS offering dedicated Microsoft device code phishing pages and warning that it lowers the barrier for low-skill operators. More than **1,000 phishing domains** were observed by late March, with campaigns affecting organizations worldwide and notable activity in the United States, Australia, Canada, France, India, Switzerland, and the United Arab Emirates; finance, HR, and transportation/logistics staff were highlighted as frequent targets. Researchers from Sekoia and Mnemonic urged defenders to disable or restrict unnecessary device code flows in **Microsoft Entra ID**, monitor device code grant sign-ins for anomalies, train users on device authentication abuse, and revoke refresh tokens when compromise is suspected.
Jul 22, 2026