discovered 30 Mar 2026

lazy_importer

C++ ★ 1911 via github-topic

AI Summary: lazy_importer is a C++ library designed to obfuscate API calls, enhancing the difficulty of reverse engineering software by ensuring that no identifiable strings or import declarations remain in memory or the executable. Key features include inlining capabilities, zero memory allocation, randomized function hashes for each compilation, and the ability to call functions without leaving a trace in data sections. This tool is particularly valuable for developers aiming to protect their software from static analysis and reverse engineering techniques.

README

lazy importer

A simple and easy to use header only library to make the life of a reverse engineer much harder.

small example

LI_FN(OutputDebugStringA)("hello world");
LI_FN(VirtualProtect).in(LI_MODULE("kernel32.dll").cached());

IDA output when compiling first line

features

Does not leave any strings in memory.
Does not allocate any memory.
Can be easily inlined.
Does not leave any imports in the executable.
Produces extremely small assembly.
Non caching functions do not leave anything in data sections.
Hashes are randomized for each compilation to defeat basic hash database attacks.

documentation

LI_FN(function_pointer) -> lazy_function
LI_FN_DEF(function_type) -> lazy_function
LI_MODULE(module_name) -> lazy_module

safe indicates that when function cannot complete its task successfully 0 is returned instead of undefined behaviour manifesting.
cached indicates that the result is only computed during the first call and later reused.
forwarded indicates that export forwarding will be correctly resolved.

`lazy_module`

function	safe	cached
Attempts to find the given module and returns its address
`get<T = void*>() -> T`	:x:	:x:
`safe<T = void*>() -> T`	:white_check_mark:	:x:
`cached<T = void*>() -> T`	:x:	:white_check_mark:
`safe_cached<T = void*>() -> T`	:white_check_mark:	:white_check_mark:
Attemps to find the given module using the given LDR_DATA_TABLE_ENTRY pointer
`in<T = void*, Ldr>(Ldr ldr_entry) -> T`	:white_check_mark:	:x:
`in_cached<T = void*, Ldr>(Ldr ldr_entry) -> T`	:white_check_mark:	:white_check_mark:

`lazy_function<F>`

function	safe	cached	forwarded
calls resolved export using given arguments
`operator()(...) -> result_of<F, ...>`	:x:	:x:	:x:
attempts to resolve an export in all loaded modules and returns the function address
`get<T = F>() -> T`	:x:	:x:	:x:
`safe<T = F>() -> T`	:white_check_mark:	:x:	:x:
`cached<T = F>() -> T`	:x:	:white_check_mark:	:x:
`safe_cached<T = F>() -> T`	:white_check_mark:	:white_check_mark:	:x:
`forwarded<T = F>() -> T`	:x:	:x:	:white_check_mark:
`forwarded_safe<T = F>() -> T`	:white_check_mark:	:x:	:white_check_mark:
`forwarded_cached<T = F>() -> T`	:x:	:white_check_mark:	:white_check_mark:
`forwarded_safe_cached<T = F>() -> T`	:white_check_mark:	:white_check_mark:	:white_check_mark:
attempts to resolve an export in the given module and returns the function address
`in<T = F, A>(A module_address) -> T`	:x:	:x:	:x:
`in_safe<T = F, A>(A module_address) -> T`	:white_check_mark:	:x:	:x:
`in_cached<T = F, A>(A module_address) -> T`	:x:	:white_check_mark:	:x:
`in_safe_cached<T = F, A>(A module_address) -> T`	:white_check_mark:	:white_check_mark:	:x:
attempts to resolve an export in `ntdll` and returns the function address
`nt<T = F>() -> T`	:x:	:x:	:x:
`nt_safe<T = F>() -> T`	:white_check_mark:	:x:	:x:
`nt_cached<T = F>() -> T`	:x:	:white_check_mark:	:x:
`nt_safe_cached<T = F>() -> T`	:white_check_mark:	:white_check_mark:	:x:

extra configuration

`#define`	effects
`LAZY_IMPORTER_NO_FORCEINLINE`	disables force inlining
`LAZY_IMPORTER_CASE_INSENSITIVE`	enables case insensitive comparison. Might be required for forwarded export resolution.
`LAZY_IMPORTER_CACHE_OPERATOR_PARENS`	uses `cached()` instead of `get()` in `operator()` of lazy_function
`LAZY_IMPORTER_RESOLVE_FORWARDED_EXPORTS`	uses `forwarded()` in `get()`. WARNING does not apply to `nt()` and `in()`.
`LAZY_IMPORTER_HARDENED_MODULE_CHECKS`	adds extra sanity checks to module enumeration.
`LAZY_IMPORTER_NO_CPP_FORWARD`	Removes dependence on `<utility>` c++ header.

example output

for ( i = *(_QWORD **)(*(_QWORD *)(__readgsqword(0x60u) + 24) + 16i64); ; i = (_QWORD *)*i )
  {
    v1 = i[6];
    v2 = *(unsigned int *)(*(signed int *)(v1 + 60) + v1 + 136);
    v3 = (_DWORD *)(v2 + v1);
    if ( v2 + v1 != v1 )
    {
      LODWORD(v4) = v3[6];
      if ( (_DWORD)v4 )
        break;
    }
LABEL_8:
    ;
  }
  while ( 1 )
  {
    v4 = (unsigned int)(v4 - 1);
    v5 = -2128831035;
    v6 = (char *)(v1 + *(unsigned int *)((unsigned int)v3[8] + 4 * v4 + v1));
    v7 = *v6;
    v8 = (signed __int64)(v6 + 1);
    if ( v7 )
    {
      do
      {
        ++v8;
        v5 = 16777619 * (v5 ^ v7);
        v7 = *(_BYTE *)(v8 - 1);
      }
      while ( v7 );
      if ( v5 == -973690651 )
        break;
    }
    if ( !(_DWORD)v4 )
      goto LABEL_8;
  }
  ((void (__fastcall *)(const char *))(v1
                                     + *(unsigned int *)(v1
                                                       + (unsigned int)v3[7]
                                                       + 4i64 * *(unsigned __int16 *)(v1 + (unsigned int)v3[9] + 2 * v4))))("hello world");

People that have supported this project

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