game-engine-security

# Security, Reverse Engineering, and Hardening in Game Engines (Unity, Unreal, Godot) This skill provides comprehensive guidelines for offensive auditing, security testing, reverse engineering, and the implementation of defenses and anti-cheat in modern game engines: **Unity Engine**, **Unreal Engine**, and **Godot Engine**. --- ## 🎮 1. Comparative Matrix of Attack Vectors by Engine | Engine | Code Format | Asset Package | Critical Attack Vectors | Typical Reverse Engineering Tools | | :--- | :--- | :--- | :--- | :--- | | **Unity** | C# (Mono IL) or native C++ (IL2CPP) | `.assets`, AssetBundles, Addressables | Dumping `global-metadata.dat`, decompiling `Assembly-CSharp.dll`, hooking with BepInEx/Frida | `dnSpy`, `ILSpy`, `Il2CppDumper`, `Il2CppInspector`, `AssetRipper` | | **Unreal Engine** | Native compiled C++ or Blueprints | `.pak`, IoStore (`.utoc`/`.ucas`) | Unpacking `.pak`, injection into non-authoritative RPCs, console commands (`EnableCheats`) | `FModel`, `UModel`, `UnrealPak`, `Cheat Engine`, `Ghidra` | | **Godot** | GDScript (`.gdc` bytecode), C# or C++ (GDExtension) | `.pck`, `.zip` | Extracting `.pck` through GDRETools, extracting the AES key from RAM, bytecode bypass | `GDRETools`, `gdsdecomp`, `x64dbg`, `IDA Pro`, `Cheat Engine` | --- ## 🛡️ 2. Hardening and Protections in Unity Engine ### 2.1 IL2CPP Compilation and Metadata Protection - **Mandatory IL2CPP**: In *Project Settings > Player*, set *Scripting Backend* to `IL2CPP`. The C# code is converted to native C++ and compiled to machine code. - **Obfuscation and Metadata Obfuscation**: - Remove or obfuscate strings in `global-metadata.dat` (class and method names) using tools such as *BeeByte Obfuscator* or *Obfuscar*. - Apply custom encryption when loading `global-metadata.dat` before the Unity runtime starts. ### 2.2 Protection Against Memory Editing - Use obfuscated types for critical variables (health, coins, score): ```csharp public struct ObfuscatedInt { private int _cryptoKey; private int _hiddenValue; public ObfuscatedInt(int value) { _cryptoKey = UnityEngine.Random.Range(1000, 99999); _hiddenValue = value ^ _cryptoKey; } public int GetValue() => _hiddenValue ^ _cryptoKey; public void SetValue(int value) => _hiddenValue = value ^ _cryptoKey; } ``` --- ## 🛡️ 3. Hardening and Protections in Unreal Engine ### 3.1 `.pak` and IoStore File Encryption - Enable AES-256 encryption in *Project Settings > Crypto* (256-bit key). - In production builds (*Shipping*), make sure `bDisableDebugConsole=true` and cheat console flags (`EnableCheats`, `ToggleDebugCamera`) are disabled through the C++ preprocessor `#if !UE_BUILD_SHIPPING`. ### 3.2 Network Security and Server Authority - **Server-Authoritative Physics & Movement**: The client sends input commands (`MoveForward`, `FireWeapon`), and the server computes positions and hits, replicating state through `ReplicatedUsing`. - **Strict RPC Validation**: ```cpp // Mandatory server-side validation in RPCs bool AGameCharacter::ServerFireWeapon_Validate(FVector AimDirection) { // Reject if the direction is NaN or beyond the possible field of view return !AimDirection.ContainsNaN() && FVector::DotProduct(GetActorForwardVector(), AimDirection) > -0.2f; } ``` --- ## 🛡️ 4. Hardening and Protections in Godot Engine ### 4.1 Custom Export Templates and `.pck` Encryption - Build export templates from the Godot source using SCons with an embedded AES key: ```bash scons platform=windows target=template_release script_encryption_key="MY_256_BIT_HEX_KEY" ``` - Change the magic bytes and header structure of the package file in `core/io/file_access_pack.cpp` to neutralize automated unpacking tools such as GDRETools. ### 4.2 Critical Logic in GDExtension C++ - Move anti-fraud logic, combat rule validation, and proprietary algorithms from GDScript into native compiled C++ modules (`GDExtension`). --- ## 🔒 5. Integrated Anti-Cheat Architecture ```mermaid graph TD Client[Game Client] -->|1. Actions / Control Inputs| Server[Authoritative Server] Server -->|2. Physical-Logical Validation| AntiCheatEngine[Anti-Cheat Engine & Heuristics] AntiCheatEngine -->|Anomaly Score| DecisionEngine{Action?} DecisionEngine -->|Severe Inconsistency| KickBan[Kick / Silent Flag / Ban] DecisionEngine -->|Within Threshold| WorldState[Updates Replicated World State] ```