# DLL Hijacking

### Overview

**DLL Hijacking** is a **Windows local privilege escalation (LPE)** technique that abuses **insecure DLL search order behavior** in **services or applications running with higher privileges** (often **SYSTEM**).

If a privileged service:

* Loads a DLL **without specifying a full path**
* And the attacker can **write to a directory searched earlier**

### Why this Works

Windows follows a **DLL search order** when loading DLLs without absolute paths:

1. Application directory
2. System32
3. System
4. Windows
5. Current working directory
6. Directories in `PATH`

If a service executable:

* Is **SYSTEM-owned**
* Loads a DLL **by name only**
* Searches a **writable directory first**

Attacker drops a malicious DLL → service loads it → **SYSTEM execution**

### Prerequisites

1. Local Code Execution
2. Vulnerable Service or Executable
3. Writable Directory in DLL Search Path
4. Ability to Restart the Service

### Steps

1. Enumerate Services:\
   **Eg**: Use:

   * **Process Monitor** (ProcMon)
   * Filter:
     * Process Name = service executable
     * Result = NAME NOT FOUND
     * Path ends in `.dll`

   This reveals **DLLs the service tries to load but cannot find**.
2. Generate and place Malicious DLL in the writable Directory.
3. Restart the Service


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