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Search: “Microsoft Defender for Office”

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Protecting organizations from AI-assisted executive impersonation and invoice fraud

Microsoft tracked a campaign of over one million AI-crafted CEO-impersonation emails seeking ~$50,000 ACH payments with fabricated ServiceNow invoices.

Between August 3 and 5, Microsoft detected a campaign of more than one million fraud emails, 87.7% of them targeting US enterprise users, sent through multiple third-party email delivery service accounts. The actor impersonated CEOs, CFOs, and presidents of targeted companies, urging accounts payable staff to process an ACH payment of nearly $50,000. Lures layered executive impersonation, lookalike domains, a fabricated ServiceNow 'Annual Subscription' invoice personalized to the recipient, and forged forwarded email threads; Microsoft found no evidence ServiceNow or the referenced executives were compromised. Microsoft observed indicators consistent with generative AI-assisted template creation, while leftover inconsistencies such as missing forwarding headers and mismatched display names gave defenders detection cues.

Microsoft Security Blog · 6d agoPhishing & fraud1

ASCII smuggling crosses over from AI prompt injection to phishing evasion

Microsoft details high-volume phishing campaign using ASCII smuggling (Unicode tag chars) for filter evasion, peaking at 2.3M messages.

Microsoft researchers observed a high-volume finance-themed phishing campaign using invisible Unicode tag characters (U+E0000–U+E007F), a technique known from AI prompt injection research as ASCII smuggling, to split lure words like 'funding' and evade email filters. Telemetry from Microsoft Defender for Office 365 showed signature hits jump from roughly 21,000 messages on February 8, 2026 to more than 1.3 million on February 9, peaking above 2.3 million on February 11, with elevated weekday activity lasting approximately three months. The discovery emerged from prompt injection protection research, showing AI-era evasion techniques crossing into traditional phishing. Most messages were flagged by layered Defender protections rather than a single Unicode-specific signal.

Microsoft Security Blog · 13d agoPhishing & fraud in the wild1

Once popular for attacking AI, ASCII smuggling is embraced by spammers

Spammers adopt ASCII smuggling—invisible Unicode tag characters—to evade email filters, with Microsoft Defender detections spiking to 2.5 million per day.

ASCII smuggling hides text in Unicode tag characters (e.g., U+E0041 for "A") that are invisible to humans but readable by LLMs and text processors. The technique gained attention as a stealthy prompt-injection vector and is now used by spammers to obfuscate keywords from email detectors. Microsoft reported Defender for Office smuggling detections jumped from roughly 21,000 per day to over 1.3 million in early February, reaching 2.5 million within four days, before falling sharply in mid-May.

Ars Technica · Security · 12d agoPhishing & fraud

Inside Knight Office, a New M365 AiTM Phishing Kit

Huntress details Knight Office, a new AiTM phishing kit stealing Microsoft 365 session tokens and registering attacker-controlled devices.

Huntress investigated an August 18, 2026 adversary-in-the-middle attack using the Knight Office phishing kit, which captured Microsoft 365 session tokens via a DocuSign-style lure routed through a Monday.com tracking link and a compromised Joomla site. After token capture, the actor enrolled an unauthorized host in Microsoft Entra ID and bound a Windows Hello for Business key credential to the account. The kit's operator console, found at IP 104.37.188.94, is built on Python Flask and hosts at least 25 .vu phishing domains. Telemetry links the kit to at least nine token-replay logins in two weeks and roughly 700 reported lure emails since April.

Huntress · 15d agoPhishing & fraud in the wild1

Phishing Attacks Serve Browser-in-the-Browser Pages, Rogue RMM Persistence

Phishing emails with browser-in-the-browser fake Adobe pages trick users into installing rogue ScreenConnect clients granting persistent remote access.

Huntress SOC investigated two August incidents where phishing links led to fake CAPTCHA checks and Adobe PDF Reader lures rendered as browser-in-the-browser (BiTB) pages spoofing legitimate domains like get.adobe.com. Victims downloaded what they believed was Acrobat Reader but actually installed ScreenConnect.ClientSetup.exe from attacker infrastructure, yielding two rogue ScreenConnect clients with service-based persistence. The attacker used cmd.exe and curl to stage a second client connecting to 144.172.115.59, leveraged a ScreenConnect Trial Relay domain for stealth, and ran HideCursor.exe as a defense-evasion binary. Incident 2 arrived via AT&T Office@Hand (RingCentral), with both chains stopped before broader impact.

Huntress · 8d agoPhishing & fraud in the wild