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October 12, 2021 04:56
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Code examples from https://nickharbour.wordpress.com/2010/07/01/writing-shellcode-with-a-c-compiler/
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// Ref: Writing Shellcode with a C Compiler (https://nickharbour.wordpress.com/) | |
PPEB __declspec(naked) get_peb(void) | |
{ | |
__asm { | |
mov eax, fs:[0x30] | |
ret | |
} | |
} | |
HMODULE __stdcall ResolveModuleHash(DWORD hash) | |
{ | |
PPEB peb; | |
LDR_DATA_TABLE_ENTRY *module_ptr, *first_mod; | |
peb = get_peb(); | |
module_ptr = (PLDR_DATA_TABLE_ENTRY)peb->Ldr->InMemoryOrderModuleList.Flink; | |
first_mod = module_ptr; | |
do { | |
if (hash_algorithm((WCHAR *)module_ptr->FullDllName.Buffer) == hash) | |
return (HMODULE)module_ptr->Reserved2[0]; | |
else | |
module_ptr = (PLDR_DATA_TABLE_ENTRY)module_ptr->Reserved1[0]; | |
} while (module_ptr && module_ptr != first_mod); // because the list wraps, | |
return INVALID_HANDLE_VALUE; | |
} | |
FARPROC __stdcall ResolveHash(DWORD moduleHash, DWORD functionHash) | |
{ | |
IMAGE_DOS_HEADER *dos_header; | |
IMAGE_NT_HEADERS *nt_headers; | |
IMAGE_EXPORT_DIRECTORY *export_dir; | |
DWORD *names, *funcs; | |
WORD *nameords; | |
int i; | |
HMODULE module; | |
module = ResolveModuleHash(moduleHash); | |
dos_header = (IMAGE_DOS_HEADER *)module; | |
nt_headers = (IMAGE_NT_HEADERS *)((char *)module + dos_header->e_lfanew); | |
export_dir = (IMAGE_EXPORT_DIRECTORY *)((char *)module + nt_headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress); | |
names = (DWORD *)((char *)module + export_dir->AddressOfNames); | |
funcs = (DWORD *)((char *)module + export_dir->AddressOfFunctions); | |
nameords = (WORD *)((char *)module + export_dir->AddressOfNameOrdinals); | |
for (i = 0; i < export_dir->NumberOfNames; i++) | |
{ | |
char *string = (char *)module + names[i]; | |
if (functionHash == hash_algorithm(string)) | |
{ | |
WORD nameord = nameords[i]; | |
DWORD funcrva = funcs[nameord]; | |
return (FARPROC)((char *)module + funcrva); | |
} | |
} | |
return NULL; | |
} |
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