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This guide walks you through building Dr.Semu from source on Windows. The build process requires Visual Studio and several dependencies.

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Prerequisites

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Required Software

  • Visual Studio 2019 or later with C++ development tools
  • CMake (version 3.10 or higher) - Download cmake-gui
  • Python 3 x64 - Download Python 3
  • Windows 10 version 1809 or later (required for ProjFS support)

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Enable ProjFS

Before building, enable Windows Projected File System using PowerShell in an elevated window: 
Enable-WindowsOptionalFeature -Online -FeatureName Client-ProjFS -NoRestart
This feature is essential for Dr.Semu’s virtual filesystem implementation.

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Building Dependencies

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1. Build pe-parse Library

Dr.Semu requires the Trail of Bits pe-parse library for PE file analysis. Generate Visual Studio Project:
  1. Open cmake-gui
  2. Set source directory to: DrSemu\shared_libs\pe_parse
  3. Set build directory to: DrSemu\shared_libs\pe_parse\build (for 32-bit)
  4. Click “Configure” and select your Visual Studio version
  5. Click “Generate”
Build 32-bit Library:
  1. Open the generated solution in \shared_libs\pe_parse\build\
  2. Build the pe-parser-library project in Release mode
  3. The output will be in \shared_libs\pe_parse\build\pe-parser-library\Release\
Build 64-bit Library:
  1. Repeat the cmake-gui process with build directory: DrSemu\shared_libs\pe_parse\build64
  2. Generate the project
  3. Build in Release mode
  4. The output will be in \shared_libs\pe_parse\build64\pe-parser-library\Release\
Configure Runtime Library: For both 32-bit and 64-bit builds:
  1. Right-click the pe-parser-library project
  2. Go to Properties → C/C++ → Code Generation
  3. Change Runtime Library to /MT (Multi-threaded)
  4. Rebuild the project
This is crucial for proper linking with Dr.Semu.

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2. Download DynamoRIO

  1. Download the latest DynamoRIO release from GitHub
  2. Extract the archive to DrSemu\bin\dynamorio
The directory structure should be: 
DrSemu/
  bin/
    dynamorio/
      bin32/
      bin64/
      ...

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Building Dr.Semu

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1. Open Solution

  1. Open DrSemu.sln in Visual Studio
  2. The solution contains multiple projects:
    • DrSemu - DynamoRIO client (core instrumentation)
    • virtual_FS_REG - Virtual filesystem and registry provider
    • LauncherCLI - Command-line launcher
    • fake_explorer - Isolated process host
    • run_detections - Detection engine

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2. Set Startup Project

Right-click LauncherCLI and select “Set as StartUp Project”

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3. Build Configuration

Select your build configuration:
  • Release|x64 - For 64-bit executables (recommended)
  • Release|x86 - For 32-bit executables

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4. Build Solution

  1. Build → Build Solution (Ctrl+Shift+B)
  2. Verify all projects build successfully
  3. Output binaries will be in bin\ directory

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Project Components

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DrSemu (DynamoRIO Client)

The core instrumentation client that hooks system calls:
  • Location: DrSemu/DrSemu.cpp
  • Output: DrSemu.dll (32-bit) and DrSemu64.dll (64-bit)
  • Dependencies: DynamoRIO SDK, pe-parse library
Key features:
  • System call interception using DynamoRIO
  • Pre/post syscall handlers
  • JSON logging of behavior

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virtual_FS_REG

Provides virtual filesystem and registry redirection:
  • Location: virtual_FS_REG/
  • Output: Static library linked into LauncherCLI
  • Dependencies: Windows ProjFS API
Implements:
  • ProjFS callbacks for file virtualization
  • Registry hive cloning and redirection

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LauncherCLI

Main executable that orchestrates analysis:
  • Location: LauncherCLI/
  • Output: DrSemu.exe
  • Dependencies: virtual_FS_REG, DynamoRIO

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Common Build Issues

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pe-parse Library Errors

Problem: Linker errors about runtime library mismatch Solution: Ensure pe-parse is built with /MT runtime library option (see step 1 above)

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ProjFS Not Available

Problem: Compilation errors about missing ProjFS headers Solution:
  • Verify Windows 10 version 1809 or later
  • Ensure ProjFS feature is enabled
  • Update Windows SDK to latest version

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DynamoRIO Not Found

Problem: Runtime error about missing DynamoRIO DLLs Solution:
  • Verify DynamoRIO is extracted to bin\dynamorio
  • Check folder structure matches expectations

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Missing Dependencies

Problem: Compilation errors about missing headers Solution: The project uses git submodules for dependencies: 
git submodule update --init --recursive
This downloads:
  • phnt (Process Hacker Native API headers)
  • nlohmann/json (JSON library)
  • spdlog (Logging library)
  • cxxopts (Command-line parsing)

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Build Output

After successful build, you’ll have: 
bin/
  DrSemu.exe              # Main launcher
  DrSemu.dll              # 32-bit DynamoRIO client
  DrSemu64.dll            # 64-bit DynamoRIO client
  explorer32.exe          # 32-bit fake explorer
  explorer64.exe          # 64-bit fake explorer
  dynamorio/              # DynamoRIO runtime
    bin32/
    bin64/

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Next Steps

After building:
  1. Run Dr.Semu: DrSemu.exe --target file_path
  2. Review generated JSON reports
  3. Create custom detection rules in dr_rules/
For development and debugging, you can define DR_TESTING in virtual_FS_REG/shared_config.h to disable certain features.

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Development Tips

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Debugging DynamoRIO Client

The DrSemu.dll client runs inside the DynamoRIO process:
  1. Set LauncherCLI as startup project
  2. Enable DynamoRIO logging: Use -verbose 2 option
  3. Use dr_printf() for logging from the client

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Testing Isolation

Test virtual filesystem:
  • Check files are redirected to virtual root
  • Verify registry keys are cloned to virtual_reg/

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Code Structure

Handler files:
  • filesystem_handlers.hpp - File system call handlers
  • registry_handlers.hpp - Registry call handlers
  • process_handlers.hpp - Process/thread handlers
  • networking_handlers.hpp - Network call handlers

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