Harden security and build resiliency with Windows Server 2025

I think the best way to describe it, it’s layers of protection.

UEFI -> DEP -> Secure Boot -> Kernel (App Control for Business) -> ELAM -> Credential Guard -> Smartscreen / Network Protection -> ASR Rules -> Defender Antivirus -> Defender for Endpoint

Depending on App Control for Business design that the customer is using:

🔒 Application Control Design Models (Ranked)

Here are typical WDAC design models, ranked from most secure (but possibly complex) to least secure (but simpler):

1. Default Deny with Trusted Signers Only (Most Secure)

• 🔐 Security: Highest — only explicitly trusted code runs (e.g., Microsoft + IT-signed apps)
• 🧰 Overhead: High — every new app needs manual approval/signing
• ⚙️ Ideal for: High-security environments (e.g., defense, critical infrastructure)

2. Signed Apps Only + Microsoft Recommended Block Rules

• ✔️ Security: Very strong — only signed apps allowed; known bad binaries blocked
• 🧠 Overhead: Moderate — fewer exceptions needed, but signing required for custom apps
• 🤖 Can be combined with Intune auto-deployments
• 📦 Best balance of security and manageability

3. Allow Microsoft + IT-Approved Catalog Apps (Hybrid)

• ✅ Security: Strong — relies on signer trust and curated app catalogs
• 🔄 Overhead: Moderate-Low — allows app updates if signed properly
• 📊 Good for: Enterprises managing both commercial and in-house software

4. Path Rules with Signed Microsoft Core Apps

• ⚠️ Security: Moderate — vulnerable to path tampering and DLL injection if not hardened
• 🛠️ Overhead: Low — easiest to maintain, especially if core apps are in fixed locations
• 🎯 Target: Lighter lockdown or compatibility testing environments

5. Audit Mode with Monitoring (Test Only)

• ❌ Security: None (no enforcement)
• 🧪 Overhead: Low — used for baseline analysis before enforcement
• 📈 Useful for: Building future enforced policies based on real-world app use

🔄 How ASR and WDAC Work Together

1. ✅ "Use advanced protection against ransomware"

• What it does: Blocks processes from making changes to files in user folders unless they're trusted/signed or have good reputation.
• How it fits with WDAC:
• WDAC might allow a signed app to run, but ASR can still block its behavior if it starts encrypting files.
• ASR provides behavioral protection against misuse of legitimate apps (e.g., Office apps with macros).

2. ✅ "Block executable files from running unless they meet a prevalence, age, or trusted list criterion"

• What it does: Uses cloud-based reputation (Microsoft Defender Cloud Protection (aka MAPS)) to determine if a file is likely trustworthy.
• How it fits with WDAC:
• WDAC has Microsoft Intelligent Security Graph (ISG) for runtime signing verification
• This ASR rule acts as a dynamic safety net, especially useful in environments where not all apps are pre-vetted or signed.
• Helps protect against zero-day or just-released malware that isn’t yet blocked by WDAC or antivirus signatures.