# What’s new in Microsoft Defender – August 2026: AI agents, MDI sensor v3.x and prompt injection

> What’s new in Microsoft Defender for August 2026: AI agent posture risk, MDI sensor v3.x migration in GA, OT connectors and prompt injection detection.

- URL: https://benjamintestart.fr/en/whats-new-microsoft-defender-august-2026/
- Author: Benjamin Testart (Devices Practice Leader & Microsoft Intune consultant)
- Published: 2026-10-10
- Updated: 2026-10-10
- Category: Security & Defender
- Language: en
- Tags: Microsoft Defender, What's new in Defender, Defender for Identity, Defender for Endpoint, Defender for Office 365, AI agent security, Exposure Management
- Version française: https://benjamintestart.fr/fr/nouveautes-microsoft-defender-aout-2026/

## TL;DR

The August 2026 edition of the Microsoft Defender monthly news covers July’s updates: AI agent posture risk in public preview, AI agent protection with Microsoft Agent 365 and migration to the Defender for Identity v3.x sensor now generally available, Defender Experts MDR P2, Armis, Dragos and Forescout OT connectors, a Linux deployment tool and detection of prompt injection in inbound email.

Microsoft Defender’s August 2026 updates are dominated by **AI agent security**, the **migration to the Defender for Identity v3.x sensor**, now generally available, and **prompt injection detection** in Defender for Office 365. As every month, the August edition of Microsoft’s monthly news covers the updates released in July 2026, and it now includes Defender for Cloud announcements visible in the Microsoft Defender portal.

On top of that come **OT connectors**, a **Linux deployment tool**, **Defender Experts MDR P2** and the end of the **Microsoft Defender Threat Intelligence (MDTI)** convergence. Here is what to remember, and what it changes for you.

## August’s updates at a glance

| Feature | Product | Status |
| --- | --- | --- |
| AI agent posture risk | Microsoft Defender | Public preview |
| AI agent protection with Microsoft Agent 365 | Microsoft Defender | Generally available |
| Active Directory domain investigation page | Defender for Identity | Generally available |
| Sensor migration from v2.x to v3.x | Defender for Identity | Generally available |
| Password risks from SaaS apps | Defender for Identity | Public preview |
| Automatic RPC auditing (sensor 3.0.8 and later) | Defender for Identity | New (status not specified) |
| Defender Experts MDR P2 | Microsoft Defender Experts | Generally available |
| Codename MDASH, agentic code scanner | Security Exposure Management | Private preview |
| Armis, Dragos and Forescout OT data connectors | Security Exposure Management | Public preview |
| AI agent runtime protection (enhancements) | Defender for Endpoint | Public preview |
| Defender Deployment Tool for Linux | Defender for Endpoint | Generally available |
| Prompt injection protection | Defender for Office 365 | New (status not specified) |
| Unified RBAC by default for new Plan 2 organizations | Defender for Office 365 | Since July 2026 |
| MDTI convergence into the Microsoft Defender portal | Defender XDR and Sentinel | Generally available since August 1 |

## Microsoft Defender: AI agent security takes center stage

### Assess AI agent posture risk

In **public preview**, Microsoft Defender **assesses posture risk for AI agents**: enterprise agents, but also **local agents discovered on endpoint devices**. Risk levels are based on active risk indicators: configuration, access, runtime activity, endpoint and user context, and active alerts.

In practice, the security team gets a risk level and recommendations to **prioritize the riskiest agents**. This is useful as soon as agents multiply without a clear inventory. Details are in [AI agent posture risk in Microsoft Defender](https://learn.microsoft.com/en-us/defender-xdr/security-for-ai/ai-agent-risk-assessment).

### Protect AI agents with Microsoft Agent 365

With a **Microsoft Agent 365 license**, Microsoft Defender provides **discovery**, **security posture**, **threat detection and investigation** and **real-time protection** for the AI agents in your tenant. This capability is **generally available**.

Onboarding involves three steps listed by Microsoft: enable data collection, connect the **Microsoft 365 app connector**, then connect **Copilot Studio** for real-time protection of Copilot Studio agents.

### Easier access to Playbook Generator

Following its general availability on May 31, **Playbook Generator** is now easier to get started with. Microsoft reduced friction around **Security Copilot wallet** provisioning and initial setup. Important reminder: it remains **included with Microsoft Sentinel** and does **not consume SCUs** for generating, testing or running playbooks.

## Defender for Identity: sensor v3.x generally available

This is the most anticipated identity announcement: **migration of sensors from v2.x to v3.x** is **generally available**. To support migrations, the **Sensors** page now shows a tooltip on servers marked **Not ready for migration**: it lists the specific reasons the server doesn’t meet the prerequisites. No more digging through documentation to understand a blocker. The reference guide is [Migrate to Defender for Identity sensor v3.x](https://learn.microsoft.com/en-us/defender-for-identity/deploy/migrate-to-sensor-v3).

More good news: Defender for Identity **automatically enables RPC auditing** on domain controllers when you upgrade to **sensor version 3.0.8 or later**. You no longer need to apply a tag manually.

Two other updates round out the picture:

- the **domain investigation page** (generally available) shows the security of an Active Directory domain: properties, deployment health, identity summary, service account breakdown, sensitive entities, active recommendations, group policies and trust relationships;
- in **public preview**, the **Password protection** page includes **password risks from SaaS apps** connected through Defender for Cloud Apps, in addition to Active Directory, Microsoft Entra ID and Okta. Apps that support SSPM, such as Salesforce and ServiceNow, appear on the Password Hygiene and Password Policies tabs. Each app requires a **Defender for Cloud Apps app connector**.

My take: the domain investigation page is a good starting point for a quick Active Directory review, especially for often-forgotten service accounts and trust relationships.

## Microsoft Defender Experts MDR P2

**Microsoft Defender Experts MDR** (formerly Microsoft Defender Experts for XDR) launches the **MDR P2** service, **generally available**. This 24/7 managed detection and response service extends to non-Microsoft sources ingested into **Microsoft Sentinel**: AWS, Okta, Proofpoint, Palo Alto Networks, Cisco, Fortinet, ZScaler and CrowdStrike. It will mainly interest organizations with heterogeneous environments that want a single MDR provider.

## Exposure Management and vulnerability management

- **Codename MDASH** (**private preview**): an **agentic code scanner** built on a multi-model AI system to detect code vulnerabilities. Scans run from **Defender CLI** or through a **GitHub connector**, and findings are reviewed in the Microsoft Defender portal.
- **MAI-Augmented scan profile** (**private preview**): available from Defender CLI, it adds **MAI-Cyber-1-Flash**, a new cyber-specialized model. You can also keep using a profile based on the existing models.
- **OT data connectors**: Microsoft Security Exposure Management supports **Armis, Dragos and Forescout**. OT assets and vulnerabilities flow into the Microsoft Defender portal, alongside your other assets. See [OT data connectors](https://learn.microsoft.com/en-us/security-exposure-management/ot-data-connectors).

## Defender for Endpoint: AI agents and Linux deployment

In **public preview**, **AI agent runtime protection** gets several enhancements:

- vendor-supported agent event interfaces now work with **standard** platform and engine update channels, with no Beta channel configuration required;
- agent-native event inspection now supports **Codex CLI** and the **GitHub Copilot app**;
- **network inspection** covers agents that don’t expose event interfaces, such as **OpenClaw** and similar Node.js-based Claw agents.

On Linux, the **Defender Deployment Tool for Linux** becomes **generally available**, starting with version **101.26042.0011**. It combines **installation, onboarding, upgrades and uninstallation** into a single workflow, validates prerequisites and works with local repositories. Monitoring relies on the **device timeline** and **advanced hunting**, with the stage, exit code and failure reason for each error. See [the Defender Deployment Tool for Linux](https://learn.microsoft.com/en-us/defender-endpoint/linux-install-with-defender-deployment-tool).

## Defender for Office 365: prompt injection and licensing

- **Prompt injection protection**: Defender for Office 365 **detects prompt injection attacks** hidden in inbound email. With AI assistants reading mailboxes, this vector is becoming very real. See [Prompt injection protection in Defender for Office 365](https://learn.microsoft.com/en-us/defender-office-365/step-by-step-guides/prompt-injection-protection-defender-for-office-365).
- **Unified RBAC by default**: since July 2026, **new Defender for Office 365 Plan 2 organizations** use the Microsoft Defender unified role-based access control (Unified RBAC) model by default.
- **Microsoft 365 E3 now includes Defender for Office 365 Plan 1**.

## Also announced this month

**Dragos, Forescout and Armis OT integrations.** The July 14 post specifies that these integrations are in **public preview** and can be enabled from the Microsoft Defender portal. The device inventory shows discovered OT devices, and the vulnerabilities view gains an **OT Partner CVEs** tab: the SOC sees OT and IT vulnerabilities in a single prioritized view.

**MDTI convergence complete.** Since **August 1**, the final phase of Microsoft Defender Threat Intelligence convergence is **generally available**, at **no additional cost**. Entity pages (IP addresses, domains, URLs, files) show a **Threat Intelligence Insights** tab. The free **Microsoft Threat Intelligence** connector in Sentinel now carries the premium data, and MDTI APIs no longer require a separate license. The Intel Profiles, Intel Explorer and Intel Projects pages are retired in favor of the **Threat Analytics** tab, with no migration needed.

**Certighost (CVE-2026-54121).** This Active Directory Certificate Services vulnerability allows an attacker to obtain certificates for domain computer accounts, including domain controllers. Fix: the **July 14, 2026 security update**. Defender for Identity raises the **Potential Certighost (CVE-2026-54121) AD CS abuse** alert. If the sensor isn’t deployed on your AD CS servers, enable Certificate Services auditing ([configure Windows event auditing](https://learn.microsoft.com/en-us/defender-for-identity/deploy/configure-windows-event-collection)).

## What I recommend doing this month

1. **Patch your Enterprise Certification Authorities** with the July 14 update, then check that Defender for Identity covers your domain controllers and AD CS servers.
2. **Plan the migration to sensor v3.x**: find the servers marked “Not ready for migration” and read the reasons shown. Target version 3.0.8 or later for automatic RPC auditing.
3. **Inventory your AI agents**: try AI agent posture risk (preview) and, if you have Agent 365, connect the Microsoft 365 app connector and Copilot Studio.
4. **Standardize your Linux deployments** with the Defender Deployment Tool and monitor them with advanced hunting.
5. **MDTI customers**: head to Threat Analytics and talk to your Microsoft account team about adjusting your license.

## Key takeaways

- Microsoft Defender assesses posture risk for AI agents in public preview, including local agents discovered on endpoint devices.
- With a Microsoft Agent 365 license, Defender provides discovery, posture, threat detection and real-time protection for the AI agents in your tenant (generally available).
- Migration of Defender for Identity sensors from v2.x to v3.x is generally available, and RPC auditing is enabled automatically from sensor 3.0.8.
- Microsoft Security Exposure Management adds OT data connectors for Armis, Dragos and Forescout, in public preview according to the announcement post.
- The Defender Deployment Tool for Linux (version 101.26042.0011 and later) combines installation, onboarding, upgrades and uninstallation (generally available).
- Defender for Office 365 detects prompt injection attacks in inbound email, and Microsoft 365 E3 now includes Defender for Office 365 Plan 1.

## Frequently asked questions

### What are the main Microsoft Defender updates for August 2026?

The August edition covers July 2026: AI agent posture risk (public preview), AI agent protection with Microsoft Agent 365 (generally available), migration to the Defender for Identity v3.x sensor (generally available), Defender Experts MDR P2, OT connectors and prompt injection detection in Defender for Office 365.

### Is migration to the Defender for Identity v3.x sensor ready for production?

Yes, migration of sensors from v2.x to v3.x is generally available. The Sensors page now shows, when you hover over the “Not ready for migration” status, the specific reasons a server doesn’t meet the prerequisites.

### Do I still need to tag domain controllers to enable RPC auditing?

No. Defender for Identity automatically enables RPC auditing on domain controllers when you upgrade to sensor version 3.0.8 or later, with no manual tag.

### What does the Microsoft Defender Threat Intelligence convergence change?

Since August 1, MDTI capabilities are available in the Microsoft Defender portal at no additional cost, through the Threat Analytics tab. The standalone Intel Profiles, Intel Explorer and Intel Projects pages are retired, and no migration action is needed.

### How does Microsoft Defender detect the Certighost vulnerability (CVE-2026-54121)?

Defender for Identity raises the “Potential Certighost (CVE-2026-54121) AD CS abuse” alert. Microsoft stresses that the primary fix remains the July 14, 2026 security update on Enterprise Certification Authorities.

## Sources and documentation

- [Microsoft Defender XDR Blog: Monthly News – August 2026](https://techcommunity.microsoft.com/t5/microsoft-defender-xdr-blog/monthly-news-august-2026/ba-p/4544388)
- [Microsoft Defender XDR Blog: Microsoft Defender now integrates with Dragos, Forescout, & Armis for OT Security](https://techcommunity.microsoft.com/t5/microsoft-defender-xdr-blog/microsoft-defender-now-integrates-with-dragos-forescout-armis/ba-p/4534936)
- [Microsoft Defender XDR Blog: MDTI convergence in Microsoft Sentinel and Defender XDR is complete](https://techcommunity.microsoft.com/t5/microsoft-defender-xdr-blog/mdti-convergence-in-microsoft-sentinel-and-defender-xdr-is/ba-p/4541279)
- [Microsoft Defender XDR Blog: Detecting CVE-2026-54121 (Certighost) with Microsoft Defender](https://techcommunity.microsoft.com/t5/microsoft-defender-xdr-blog/detecting-cve-2026-54121-certighost-with-microsoft-defender/ba-p/4542861)
- [Microsoft Learn: AI agent posture risk in Microsoft Defender](https://learn.microsoft.com/en-us/defender-xdr/security-for-ai/ai-agent-risk-assessment)
- [Microsoft Learn: Migrate to Defender for Identity sensor v3.x](https://learn.microsoft.com/en-us/defender-for-identity/deploy/migrate-to-sensor-v3)
- [Microsoft Learn: OT data connectors](https://learn.microsoft.com/en-us/security-exposure-management/ot-data-connectors)
- [Microsoft Learn: Defender Deployment Tool for Linux](https://learn.microsoft.com/en-us/defender-endpoint/linux-install-with-defender-deployment-tool)
- [Microsoft Learn: Prompt injection protection in Defender for Office 365](https://learn.microsoft.com/en-us/defender-office-365/step-by-step-guides/prompt-injection-protection-defender-for-office-365)
- [Microsoft Learn: Configure Windows event auditing – Microsoft Defender for Identity](https://learn.microsoft.com/en-us/defender-for-identity/deploy/configure-windows-event-collection)