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#گزارش RedCanary از تهدیدات میانه سال
@Engineer_Computer

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پاسخ به یک سوال مهم :

پیرو حادثه crowdstrike و مشکل درایور این محصول که منجر به بلو اسکرین در سراسر جهان شد سوالی به میان میاید :
ویندوز با Patchguard که از انتهای ویندوز xp ارائه کرد دیگر اجازه نمی‌دهد هر کسی در کرنل دستکاری کند ، اما EDR و XDR ها ادعا می‌کنند توسط درایور ها در تعامل با کرنل هستند . حد این تعامل چیست که حادثه ای چون CrowdStrike رخ می‌دهد؟ و اینکه چرا مایکروسافت اخیرا جلسه ای بدون حضور خبرنگاران با اصحاب تولید کننده محصولاتی چون XDR و EDR گذاشته تا ایشان را از کرنل بیرون کند؟!!

من تعاملی با ChatGPT داشتم به جواب زیر رسیدم

Windows PatchGuard (also known as Kernel Patch Protection or KPP) is a security feature introduced by Microsoft to prevent unauthorized code from patching or modifying the Windows kernel on 64-bit systems. Its main goal is to maintain kernel integrity by ensuring that only trusted and signed code operates within the kernel space, protecting against malicious attacks, rootkits, or unauthorized kernel modifications.

### Relation Between Windows PatchGuard and EDR Drivers

#### 1. Kernel-Level Drivers and PatchGuard
- EDR Driver Requirements: Many EDR (Endpoint Detection and Response) solutions require kernel-level drivers to monitor system events, processes, and behavior in real time. These drivers operate in kernel mode, where they have higher privileges to access and monitor sensitive operations (file access, memory usage, etc.). However, PatchGuard enforces strict rules on what can and cannot interact with or modify the kernel.

- PatchGuard Restrictions: PatchGuard specifically blocks unauthorized drivers or software from modifying critical parts of the Windows kernel, such as:
- System Service Denoscriptor Table (SSDT) hooks
- Interrupt Denoscriptor Table (IDT) hooks
- Kernel Object Manipulation
- Modification of the Kernel Debugger

This ensures that the kernel remains in a known, stable state, preventing malware or poorly written drivers from tampering with it. Thus, any legitimate EDR driver must respect PatchGuard's restrictions, meaning that it cannot perform kernel patching or directly modify protected kernel structures.

#### 2. Signed Drivers and PatchGuard Compliance
- Driver Signing: For EDR drivers to function within the constraints of PatchGuard, they must be properly signed with a valid digital signature. Microsoft enforces driver signing to ensure that only trusted drivers are loaded into kernel space. Drivers that attempt to bypass or disable PatchGuard violate this trust model and are blocked by the system.

- Windows Hardware Quality Labs (WHQL) Certification: Most reputable EDR vendors will seek WHQL certification for their drivers, ensuring that they operate within Microsoft's guidelines for kernel interaction. This certification process ensures that the driver respects PatchGuard’s policies and doesn’t introduce instability or security vulnerabilities.

#### 3. Driver Operation Without Violating PatchGuard
- Non-Patching Approach: EDR drivers must monitor and respond to system events without directly modifying kernel structures or patching kernel code, which would violate PatchGuard. Instead, they:
- Hook into legitimate, documented APIs that provide system monitoring capabilities.
- Rely on Windows Filtering Platform (WFP), ETW (Event Tracing for Windows), or Hypervisor-protected Code Integrity (HVCI) for monitoring low-level events.
- Use legitimate kernel interfaces to gather data about processes, network activity, and file operations without modifying protected kernel data structures.

- User Mode and Kernel Mode Balance: Some EDR solutions split their functionality between user-mode agents and kernel-mode drivers. The driver performs low-level monitoring, while the user-mode components handle less sensitive tasks, ensuring that EDR solutions work effectively within the boundaries set by PatchGuard.
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@Engineer_Computer

#cybersecurity #threathunting #cyberforensics #Stuxnet #risk #edr #xdr

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