Source: Microsoft Security Blog

7 stories in the last 30d

Microsoft tracks ongoing cloud intrusions where passkey-themed helpdesk lures enable AiTM credential theft, MFA persistence, and SharePoint data theft.

Microsoft Security Research is tracking active cloud-based intrusions, observed since May 2026, that begin with helpdesk impersonation calls and SMS lures urging urgent passkey, MFA, or SSO updates. The lures lead to adversary-in-the-middle phishing or device-code authentication flows that capture credentials and session tokens or grant actor access, after which the actors add authentication methods, conduct Microsoft Graph reconnaissance, and download SharePoint and OneDrive content via REST APIs. Phishing domains embed victim organization names as subdomains (e.g., contoso.add-passkey[.]com), are often registered with Nicenic, and go operational within hours. Microsoft advises revoking sessions and removing unauthorized authentication methods for confirmed compromises.

Microsoft Security Blogupdated Sep 11, 17:26 UTC · 4d agofirst Sep 9, 17:41 UTC · 6d agoThreat actor in the wild 13 sources2

Detect and disrupt AI-themed attacks with Microsoft Defender

Microsoft Threat Intelligence reports criminal campaigns impersonating ChatGPT, Copilot, Claude, and DeepSeek in phishing, AiTM, and malvertising attacks reaching 100,000 emails daily.

Microsoft Threat Intelligence observed a growing set of campaigns that abuse trust in popular AI brands: a ChatGPT-themed phishing campaign sent up to 100,000 emails in one day to steal payment card data, and a Claude-themed campaign used adversary-in-the-middle techniques to harvest credentials and access tokens. Other campaigns included malvertising for a fake AI Windows plugin delivering the Vidar stealer and fraudulent DeepSeek installers distributed via GitHub. Initial access broker Storm-3075 used AI-themed malvertising to distribute payloads for multiple downstream actors, and Microsoft notes the AI services themselves were not compromised. Microsoft also details Defender protections such as Safe Links, Safe Attachments, and attack disruption against these multi-stage lures.

Microsoft Security BlogSep 10, 16:00 UTC · 5d agoPhishing & fraud in the wild1

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 BlogSep 3, 16:00 UTC · 12d agoPhishing & fraud in the wild

Impersonating IT support: how threat actors turn a remote session into enterprise-wide access

Microsoft details Teams IT-support impersonation campaigns deploying Node.js implants, AD reconnaissance, and WinRM lateral movement toward domain controllers.

Microsoft Threat Intelligence describes a human-operated campaign where attackers impersonate IT/helpdesk staff via Microsoft Teams external collaboration, talk users into granting remote sessions, and use RMM tools for interactive access. During the session they run PowerShell to silently install a malicious MSI that stages a portable Node.js runtime and obfuscated JavaScript implant for C2, executing follow-on payloads via rundll32. Operators then perform host and Active Directory reconnaissance, capture desktop screenshots, and pivot via WinRM on port 5985 to domain controllers and certificate authorities. The hands-on-keyboard chain, which can precede data theft and ransomware, blends into normal operations by relying on Teams, Quick Assist, msiexec, and Node.js; Microsoft shares hunting and mitigation guidance.

Microsoft Security BlogSep 2, 22:51 UTC · 13d agoThreat actor in the wild

Counterfeit installers to system compromise: Tracking a deceptive software download campaign

Microsoft tracks a counterfeit software-installer campaign compromising multinationals' China operations, moderately linked to the Silver Fox (Yinhu) actor.

Microsoft Defender Experts is tracking an active campaign using spoofed software download sites for brands such as Razer, Kaspersky, Microsoft Edge, Calibre, and Baidu Netdisk on .com.cn and .hl.cn domains, delivering installer archives whose hashes change per download, indicating server-side payload generation. The implants establish persistence, weaken security protections, and communicate with attacker-controlled infrastructure, with confirmed compromises across healthcare, manufacturing, gaming, technology, logistics, government, and education. Microsoft assesses with moderate confidence that the activity matches the publicly reported Silver Fox (Yinhu) fake software campaign; it has not attributed it to a nation-state actor.

Microsoft Security BlogSep 1, 22:48 UTC · 14d agoThreat actor in the wild1

TerminalFix campaign deploys a reverse tunnel through multistage intrusion

Microsoft Threat Intelligence details the TerminalFix campaign, which uses fake CAPTCHA prompts, DLL sideloading, and reverse tunnels in multistage intrusions.

Microsoft Threat Intelligence published analysis of a ClickFix-style campaign dubbed TerminalFix. The intrusion chain relies on fake CAPTCHA social engineering and DLL sideloading, and the attackers deploy a reverse tunnel to maintain access through a multistage intrusion. Microsoft released detections and threat hunting guidance for defenders.

Microsoft Security BlogAug 29, 03:43 UTC · 17d agoThreat actor in the wild

When AI infrastructure becomes the target: Securing gateways and control points

Microsoft Threat Intelligence details attacks on exposed AI workloads exploiting LiteLLM gateways for credential harvesting, persistence, and cryptomining.

Microsoft Threat Intelligence examines attacks targeting exposed AI workloads, including exploitation of LiteLLM gateway deployments. Post-exploitation activity includes credential harvesting, establishing persistence, and cryptomining. The post urges defenders to secure AI infrastructure gateways and control points; the available text does not name threat actors, CVEs, or provide IOCs.

Microsoft Security BlogAug 26, 16:43 UTC · 20d agoExploit / PoC in the wild