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Exchange Online

5 mentions in 7 days · 5 in 30 days · 5 total · first seen · last

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Hackers Favor US Eastern Business Hours in M365 Phishing Campaign

KnowBe4 tracked 29,785 phishing emails abusing Microsoft 365 Direct Send to spoof internal senders while timing sends to US Eastern business hours.

KnowBe4 Threat Lab observed 29,785 confirmed phishing emails between July and August 2026 abusing Microsoft 365's Direct Send feature, which lets devices and legacy apps send mail without a dedicated account. The emails appeared to come from trusted internal addresses such as HR or accounting, bypassing email gateways by connecting directly to Exchange Online MX endpoints, with activity peaking on Monday-Tuesday during US Eastern business hours and near-zero weekend volume. About 35% of the messages carried malicious attachments like fake invoices, voicemail alerts, and OneDrive shares, and 4,023 used reply-to addresses on different domains to capture employee responses. Researchers recommended strict DMARC enforcement, connector restrictions, DKIM signing, and checking for the 'X-MS-Exchange-Organization-AuthAs: Anonymous' Exchange header.

Infosecurity Magazineupdated · 4d agofirst · 4d agoPhishing & fraud in the wild 13 sources1

Attackers use passkey-themed scams to hijack Microsoft 365 accounts

Microsoft tracks ongoing M365 cloud intrusions since May using passkey-themed helpdesk vishing, AiTM phishing, and device-code abuse.

Microsoft Security Research has tracked active cloud intrusions since May in which attackers posing as IT helpdesk staff lured employees with fake passkey/MFA enrollment requests. Attacks used adversary-in-the-middle phishing pages, device-code authentication flows, and Teams messages from compromised accounts. Attackers registered their own MFA methods, enumerated tenants via Microsoft Graph, and accessed SharePoint, OneDrive, and Exchange Online data, throttling activity below 1000 files/emails per hour.

CSO Onlineupdated · 4d agofirst · 4d agoThreat actor in the wild 13 sources1

Attackers call employees’ personal phones to break into Microsoft 365 accounts

Microsoft tracks vishing campaigns by Storm-3121 and Storm-3032 that impersonate IT staff, phish Microsoft 365 credentials, and steal cloud data.

Microsoft Security Research has tracked a campaign since May 2026 in which attackers call or text employees' personal phones posing as IT staff, using passkey/MFA/SSO lures to run adversary-in-the-middle phishing or device-code authentication flows. Attackers register their own MFA methods for durable persistence, abuse Microsoft Graph for tenant discovery, and download SharePoint, OneDrive, and Exchange data below 1,000 files or emails per hour to avoid detection. Microsoft attributes initial access to actors including Storm-3121, which feeds ShinyHunters and Falcon extortion operations, and Storm-3032, the Helix extortion operation descended from BlackFile.

Help Net Securityupdated · 4d agofirst · 5d agoPhishing & fraud in the wild 13 sources1

Hackers Use Passkey-Themed Phishing to Hijack Microsoft 365 Accounts and Steal Cloud Data

Microsoft reports passkey-themed phishing campaigns hijacking Microsoft 365 accounts via AiTM and device-code flows, then exfiltrating cloud data.

Microsoft researchers identified passkey-themed phishing across cloud intrusions observed since May 2026, where callers posing as IT support direct victims to lookalike sign-in pages. The flows include adversary-in-the-middle phishing and device-code authentication, letting attackers capture usable sessions even when MFA succeeds, followed by rogue MFA registration for persistence. Attackers enumerate tenants via Microsoft Graph and collect SharePoint, OneDrive, and Exchange data at rates below 1,000 items per hour; lure domains include passkeyhelpdesk.com and setupmypasskey.com.

Cyber Security Newsupdated · 4d agofirst · 5d agoPhishing & fraud in the wild 13 sources

Hackers Pose as IT Support to Hijack Microsoft 365 Accounts With Fake Passkey Alerts

Microsoft warns of vishing campaigns by Storm-3121 and Storm-3032 hijacking Microsoft 365 accounts via fake passkey alerts, adding attacker-controlled MFA and exfiltrating cloud data.

Microsoft Security Research has tracked the campaign since May 2026: callers posing as IT helpdesk staff tell employees to urgently update passkeys, MFA, or SSO settings via domains such as add-passkey[.]com and contoso[.]add-passkey[.]com. The lures lead to adversary-in-the-middle phishing or device-code authentication flows that yield credentials, session tokens, or OAuth tokens, after which attackers enroll their own MFA methods for persistence and run Microsoft Graph reconnaissance. They then collect SharePoint, OneDrive, and sometimes Exchange Online data at deliberately low rates (often under 1,000 files or messages per hour), with python-httpx seen in high-volume file access. Microsoft attributes initial access tradecraft to Storm-3121 and Storm-3032, linked respectively to ShinyHunters/Falcon and BlackFile/Helix extortion operations.

GBHackersupdated · 4d agofirst · 5d agoPhishing & fraud in the wild 13 sources1

Appears with

vendor Microsoft 5product Microsoft 365 5product OneDrive 4product SharePoint 4product Microsoft Graph 3organization Microsoft 3threat actor BlackFile 2threat actor Helix 2threat actor ShinyHunters 2threat actor Storm-3032 2threat actor Storm-3121 2organization KnowBe4 1product Direct Send 1organization Infosecurity Magazine 1product Microsoft Defender for Endpoint 1organization BigBear 1
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