├── .gitattributes ├── .gitignore ├── LICENSE ├── README.md ├── assets ├── after_call.png ├── after_mba.png ├── after_xref.png ├── before_call.png └── before_xref.png ├── premake5.lua └── source ├── limbo.h ├── limbo ├── defines.h ├── emulation.h ├── helpers.h ├── mba.h └── rng.h └── main.cpp /.gitattributes: -------------------------------------------------------------------------------- 1 | ############################################################################### 2 | # Set default behavior to automatically normalize line endings. 3 | ############################################################################### 4 | * text=auto 5 | 6 | ############################################################################### 7 | # Set default behavior for command prompt diff. 8 | # 9 | # This is need for earlier builds of msysgit that does not have it on by 10 | # default for csharp files. 11 | # Note: This is only used by command line 12 | ############################################################################### 13 | #*.cs diff=csharp 14 | 15 | ############################################################################### 16 | # Set the merge driver for project and solution files 17 | # 18 | # Merging from the command prompt will add diff markers to the files if there 19 | # are conflicts (Merging from VS is not affected by the settings below, in VS 20 | # the diff markers are never inserted). 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The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # limba 2 | Compile-time control flow obfuscation using MBA (Mixed Boolean-Arithmetic). This project is derived from another project I am working on named ``limbo``, which is why the project files use this name. Keep in mind that this is more of a proof-of-concept rather than something ready to use in production code. 3 | 4 | ## Description 5 | Control flow between function calls is fairly easy to trace in normal binaries. 6 |
7 | Pre-obfuscation pictures 8 | 9 | ![before_xref](/assets/before_xref.png) 10 | ![before_call](/assets/before_call.png) 11 | 12 |
13 | 14 | limba will generate boilerplate code that obfuscates the actual jump address using MBA. The MBA rewrite rules and address offset is randomized each compilation to hinder analysis. It is important to note the actual function body is **NOT** obfuscated and is still present in the binary, only function calls will be obfuscated. 15 |
16 | Post-obfuscation pictures 17 | 18 | ![after_xref](/assets/after_xref.png) 19 | ![after_call](/assets/after_call.png) 20 | ![after_mba](/assets/after_mba.png) 21 | 22 |
23 | 24 | 25 | ## Support 26 | - The project has been developed using Clang(-CL) so this is the recommended compiler, GCC isn't actively supported and may (or may not) work. MSVC is **not** supported as I found no way to make it not emit a direct pointer to the original function 27 | - The codebase requires C++20 to compile. Compile time is a major constraint so I used a some C++20 features that reduced compilation time in my testing. The code can be modified to support C++17 (see ``emulation.h``) 28 | 29 | ## Usage 30 | The included example uses ``premake`` for project configuration. You can generate the project files by running ``premake5 vs2022`` in the root folder. Alternatively, the relevant header files can be copied into your own project. 31 | 32 | Sample usage: 33 | ```cpp 34 | LIMBO_OBFUSCATED_FUNC(, , ) 35 | { 36 | // function body 37 | 38 | return 39 | } 40 | ``` 41 | 42 | ## Limitations 43 | - Only a small set of MBA rules have been included 44 | - Opaque predicates are needed to avoid trivial optimization 45 | - Since a protected function will only have one "wrapper" function, it's easy to figure out and patch the protection with dynamic analysis and scripting 46 | - Compilation time may be negatively impacted if the protection is used on a large number of functions 47 | 48 | ## Acknowledgements 49 | Great open-source projects that were a great help during development 50 | - https://github.com/JustasMasiulis/xorstr 51 | - https://github.com/llxiaoyuan/oxorany 52 | - https://github.com/Deniskore/nand_nor 53 | -------------------------------------------------------------------------------- /assets/after_call.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ThatLing/limba/0e94f3b9d02651826d4adbbe2a7adc9f7fb13536/assets/after_call.png -------------------------------------------------------------------------------- /assets/after_mba.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ThatLing/limba/0e94f3b9d02651826d4adbbe2a7adc9f7fb13536/assets/after_mba.png -------------------------------------------------------------------------------- /assets/after_xref.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ThatLing/limba/0e94f3b9d02651826d4adbbe2a7adc9f7fb13536/assets/after_xref.png -------------------------------------------------------------------------------- /assets/before_call.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ThatLing/limba/0e94f3b9d02651826d4adbbe2a7adc9f7fb13536/assets/before_call.png -------------------------------------------------------------------------------- /assets/before_xref.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/ThatLing/limba/0e94f3b9d02651826d4adbbe2a7adc9f7fb13536/assets/before_xref.png -------------------------------------------------------------------------------- /premake5.lua: -------------------------------------------------------------------------------- 1 | assert(_ACTION ~= nil, "no action (vs20**, gmake or xcode for example) provided!") 2 | 3 | -- Clean Function -- 4 | newaction { 5 | trigger = "clean", 6 | description = "clean the software", 7 | execute = function() 8 | print("Cleaning project") 9 | os.rmdir("./limbo") 10 | end 11 | } 12 | 13 | if (_ACTION ~= "vs2022" and _ACTION ~= "clean") then 14 | error("The only supported compilation platform for this project (limbo) on Windows is Visual Studio 2022.") 15 | end 16 | 17 | 18 | workspace "limbo" 19 | language "C++" 20 | cppdialect "C++20" 21 | systemversion "latest" 22 | toolset "clang" 23 | 24 | kind "ConsoleApp" 25 | targetextension ".exe" 26 | 27 | location "limbo" 28 | objdir "limbo/intermediate" 29 | 30 | flags { "NoPCH", "MultiProcessorCompile", "NoManifest" } 31 | defines { 32 | "_CRT_NONSTDC_NO_WARNINGS", 33 | "_CRT_SECURE_NO_WARNINGS", 34 | "STRICT" 35 | } 36 | vectorextensions "AVX2" 37 | configurations { "Release", "Debug" } 38 | architecture "x86_64" 39 | exceptionhandling "SEH" 40 | 41 | filter "configurations:Release" 42 | symbols "Off" 43 | optimize "Speed" 44 | floatingpoint "Fast" 45 | omitframepointer "On" 46 | flags { "LinkTimeOptimization" } 47 | 48 | defines "NDEBUG" 49 | targetdir "limbo/release" 50 | 51 | filter "configurations:Debug" 52 | symbols "Full" 53 | optimize "Debug" 54 | 55 | defines { "DEBUG", "_DEBUG" } 56 | targetdir "limbo/debug" 57 | 58 | filter {} 59 | 60 | project "limbo" 61 | files { "source/**.h", "source/**.hpp", "source/**.c", "source/**.cpp" } 62 | vpaths { 63 | ["Header Files/*"] = { "source/**.h", "source/**.hpp" }, 64 | ["Source Files/*"] = { "source/**.c", "source/**.cpp" } 65 | } 66 | 67 | includedirs { 68 | "source", 69 | "source/limbo", 70 | } 71 | -------------------------------------------------------------------------------- /source/limbo.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | #include "limbo/defines.h" 20 | 21 | #include "limbo/rng.h" 22 | #include "limbo/helpers.h" 23 | #include "limbo/emulation.h" 24 | #include "limbo/mba.h" 25 | -------------------------------------------------------------------------------- /source/limbo/defines.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | #define _LIMBO_CAT(a, b) a ## b 20 | #define LIMBO_CAT(a, b) _LIMBO_CAT(a, b) 21 | 22 | #define LIMBO_RAND limbo::rng::random_int<__COUNTER__>() 23 | #define LIMBO_RAND_FASTSEED(seed) seed * 0x101 /* yolo */ 24 | 25 | #ifdef DEBUG 26 | #define LIMBO_FORCEINLINE 27 | #define LIMBO_NOINLINE 28 | #else 29 | #if defined(__clang__) || defined(__GNUC__) 30 | #define LIMBO_FORCEINLINE __attribute__((always_inline)) inline 31 | #define LIMBO_NOINLINE __attribute__((noinline)) 32 | #else 33 | #error "Unsupported compiler" 34 | #endif 35 | #endif 36 | -------------------------------------------------------------------------------- /source/limbo/emulation.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | namespace limbo 20 | { 21 | // 22 | // This namespace implements "emulation" of arithmetic expressions 23 | // NOTE: Using 'auto' in the function prototypes below requires C++20 24 | // but decreased compile time in my testing (also looks cleaner). 25 | // To enable C++17 support, replace the 'auto' with 'template ' 26 | // 27 | namespace emulation 28 | { 29 | template 30 | LIMBO_FORCEINLINE auto AddR(auto rhs, auto lhs); 31 | 32 | template 33 | LIMBO_FORCEINLINE auto SubR(auto rhs, auto lhs); 34 | 35 | template 36 | LIMBO_FORCEINLINE auto OrR(auto rhs, auto lhs); 37 | 38 | template 39 | LIMBO_FORCEINLINE auto XorR(auto rhs, auto lhs); 40 | 41 | template 42 | LIMBO_FORCEINLINE auto AndR(auto rhs, auto lhs); 43 | 44 | // // 45 | 46 | LIMBO_FORCEINLINE auto Add(auto rhs, auto lhs) 47 | { 48 | auto tmp = limbo::helpers::load_from_reg(rhs); 49 | return tmp + lhs; 50 | } 51 | 52 | LIMBO_FORCEINLINE auto Sub(auto rhs, auto lhs) 53 | { 54 | auto tmp = limbo::helpers::load_from_reg(rhs); 55 | return tmp - lhs; 56 | } 57 | 58 | LIMBO_FORCEINLINE auto Mul(auto rhs, auto lhs) 59 | { 60 | auto tmp = limbo::helpers::load_from_reg(rhs); 61 | return tmp * lhs; 62 | } 63 | 64 | LIMBO_FORCEINLINE auto Div(auto rhs, auto lhs) 65 | { 66 | auto tmp = limbo::helpers::load_from_reg(rhs); 67 | return tmp / lhs; 68 | } 69 | 70 | LIMBO_FORCEINLINE auto And(auto rhs, auto lhs) 71 | { 72 | auto tmp = limbo::helpers::load_from_reg(rhs); 73 | return tmp & lhs; 74 | } 75 | 76 | LIMBO_FORCEINLINE auto Or(auto rhs, auto lhs) 77 | { 78 | auto tmp = limbo::helpers::load_from_reg(rhs); 79 | return tmp | lhs; 80 | } 81 | 82 | LIMBO_FORCEINLINE auto Not(auto rhs) 83 | { 84 | auto tmp = limbo::helpers::load_from_reg(rhs); 85 | return ~tmp; 86 | } 87 | 88 | LIMBO_FORCEINLINE auto Minus(auto rhs) 89 | { 90 | auto tmp = limbo::helpers::load_from_reg(rhs); 91 | return -tmp; 92 | } 93 | 94 | LIMBO_FORCEINLINE auto Xor(auto rhs, auto lhs) 95 | { 96 | auto tmp = limbo::helpers::load_from_reg(rhs); 97 | return tmp ^ lhs; 98 | } 99 | 100 | LIMBO_FORCEINLINE auto Shl(auto rhs, auto lhs) 101 | { 102 | auto tmp = limbo::helpers::load_from_reg(rhs); 103 | return tmp << lhs; 104 | } 105 | 106 | LIMBO_FORCEINLINE auto Shr(auto rhs, auto lhs) 107 | { 108 | auto tmp = limbo::helpers::load_from_reg(rhs); 109 | return tmp >> lhs; 110 | } 111 | 112 | // // 113 | // TODO: Add more/better rewrite rules 114 | 115 | template 116 | LIMBO_FORCEINLINE auto Add2(auto rhs, auto lhs) 117 | { 118 | // (rhs & lhs) + (rhs | lhs) 119 | return AddR(AndR(rhs, lhs), OrR(rhs, lhs)); 120 | } 121 | 122 | template 123 | LIMBO_FORCEINLINE auto Add3(auto rhs, auto lhs) 124 | { 125 | // (rhs ^ lhs) + 2 * (rhs & lhs) 126 | return AddR(XorR(rhs, lhs), Mul(2, AndR(rhs, lhs))); 127 | } 128 | 129 | 130 | template 131 | LIMBO_FORCEINLINE auto Sub2(auto rhs, auto lhs) 132 | { 133 | // (rhs ^ -lhs) + 2 * (rhs & -lhs) 134 | return AddR(XorR(rhs, Minus(lhs)), Mul(2, AndR(rhs, Minus(lhs)))); 135 | } 136 | 137 | template 138 | LIMBO_FORCEINLINE auto Sub3(auto rhs, auto lhs) 139 | { 140 | // (rhs + 1) + ~lhs 141 | return AddR(AddR(rhs, 1), Not(lhs)); 142 | } 143 | 144 | 145 | template 146 | LIMBO_FORCEINLINE auto And2(auto rhs, auto lhs) 147 | { 148 | // (~rhs | lhs) - ~rhs 149 | return SubR(OrR(Not(rhs), lhs), Not(rhs)); 150 | } 151 | 152 | template 153 | LIMBO_FORCEINLINE auto And3(auto rhs, auto lhs) 154 | { 155 | // ((~rhs | lhs) + rhs) + 1 156 | return AddR(AddR(OrR(Not(rhs), lhs), rhs), 1); 157 | } 158 | 159 | 160 | template 161 | LIMBO_FORCEINLINE auto Or2(auto rhs, auto lhs) 162 | { 163 | // (rhs & ~lhs) + lhs 164 | return AddR(AndR(rhs, Not(lhs)), lhs); 165 | } 166 | 167 | template 168 | LIMBO_FORCEINLINE auto Or3(auto rhs, auto lhs) 169 | { 170 | // ((rhs + lhs) + 1) + ((-rhs - 1) | (-lhs - 1)) 171 | return AddR(AddR(AddR(rhs, lhs), 1), OrR(SubR(Minus(rhs), 1), SubR(Minus(lhs), 1))); 172 | } 173 | 174 | 175 | template 176 | LIMBO_FORCEINLINE auto Xor2(auto rhs, auto lhs) 177 | { 178 | // (~rhs & lhs) | (rhs & ~lhs) 179 | return OrR(AndR(Not(rhs), lhs), AndR(rhs, Not(lhs))); 180 | } 181 | 182 | template 183 | LIMBO_FORCEINLINE auto Xor3(auto rhs, auto lhs) 184 | { 185 | // (rhs | lhs) - (rhs & rhs) 186 | return SubR(OrR(rhs, lhs), AndR(rhs, lhs)); 187 | } 188 | 189 | // // 190 | 191 | template 192 | LIMBO_FORCEINLINE auto AddR(auto rhs, auto lhs) 193 | { 194 | #ifdef DEBUG 195 | // Don't emulate on debug builds 196 | return Add(rhs, lhs); 197 | #else 198 | // Check how many iterations left 199 | if constexpr (N > 0) 200 | { 201 | constexpr auto i = R % 2; 202 | 203 | if constexpr (i == 0) 204 | { 205 | return Add2(rhs, lhs); 206 | } 207 | else 208 | { 209 | return Add3(rhs, lhs); 210 | } 211 | } 212 | else 213 | { 214 | return Add(rhs, lhs); 215 | } 216 | #endif 217 | } 218 | 219 | template 220 | LIMBO_FORCEINLINE auto SubR(auto rhs, auto lhs) 221 | { 222 | #ifdef DEBUG 223 | // Don't emulate on debug builds 224 | return Sub(rhs, lhs); 225 | #else 226 | if constexpr (N > 0) 227 | { 228 | constexpr auto i = R % 2; 229 | 230 | if constexpr (i == 0) 231 | { 232 | return Sub2(rhs, lhs); 233 | } 234 | else 235 | { 236 | return Sub3(rhs, lhs); 237 | } 238 | } 239 | else 240 | { 241 | return Sub(rhs, lhs); 242 | } 243 | #endif 244 | } 245 | 246 | template 247 | LIMBO_FORCEINLINE auto AndR(auto rhs, auto lhs) 248 | { 249 | #ifdef DEBUG 250 | // Don't emulate on debug builds 251 | return And(rhs, lhs); 252 | #else 253 | if constexpr (N > 0) 254 | { 255 | constexpr auto i = R % 2; 256 | 257 | if constexpr (i == 0) 258 | { 259 | return And2(rhs, lhs); 260 | } 261 | else 262 | { 263 | return And3(rhs, lhs); 264 | } 265 | } 266 | else 267 | { 268 | return And(rhs, lhs); 269 | } 270 | #endif 271 | } 272 | 273 | template 274 | LIMBO_FORCEINLINE auto OrR(auto rhs, auto lhs) 275 | { 276 | #ifdef DEBUG 277 | // Don't emulate on debug builds 278 | return Or(rhs, lhs); 279 | #else 280 | if constexpr (N > 0) 281 | { 282 | constexpr auto i = R % 3; 283 | 284 | if constexpr (i == 0) 285 | { 286 | return Or2(rhs, lhs); 287 | } 288 | else 289 | { 290 | return Or3(rhs, lhs); 291 | } 292 | } 293 | else 294 | { 295 | return Or(rhs, lhs); 296 | } 297 | #endif 298 | } 299 | 300 | template 301 | LIMBO_FORCEINLINE auto XorR(auto rhs, auto lhs) 302 | { 303 | #ifdef DEBUG 304 | // Don't emulate on debug builds 305 | return Xor(rhs, lhs); 306 | #else 307 | if constexpr (N > 0) 308 | { 309 | constexpr auto i = R % 5; 310 | 311 | if constexpr (i == 0) 312 | { 313 | return Xor2(rhs, lhs); 314 | } 315 | else 316 | { 317 | return Xor3(rhs, lhs); 318 | } 319 | } 320 | else 321 | { 322 | return Xor(rhs, lhs); 323 | } 324 | #endif 325 | } 326 | } 327 | } 328 | -------------------------------------------------------------------------------- /source/limbo/helpers.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | #include 20 | 21 | namespace limbo 22 | { 23 | // 24 | // This namespace implements helper/utility functions that make our life easier 25 | // 26 | namespace helpers 27 | { 28 | // 29 | // Forces the compiler to generate code to load a value from a register instead of putting it into .data 30 | // Modified from xorstr (https://github.com/JustasMasiulis/xorstr/blob/master/include/xorstr.hpp#L88) 31 | // 32 | template 33 | LIMBO_FORCEINLINE constexpr T load_from_reg(T value) noexcept 34 | { 35 | #if defined(__clang__) || defined(__GNUC__) 36 | // Handles Clang(-CL) and GCC. This generates cleaner asm so we prefer this for Clang-CL 37 | asm( 38 | "" 39 | : "=r"(value) 40 | : "0"(value) 41 | : 42 | ); 43 | 44 | return value; 45 | #else 46 | #error "Unsupported compiler" 47 | #endif 48 | } 49 | } 50 | } 51 | -------------------------------------------------------------------------------- /source/limbo/mba.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | #ifdef DEBUG 20 | #define LIMBO_OBFUSCATED_FUNC(ret, name, ...) \ 21 | ret name(__VA_ARGS__) 22 | #else 23 | // I don't really like this macro, but it's the only one I've found so far. 24 | // We rename the original function to something different and create a dispatcher function 25 | // with the correct name. 26 | #define LIMBO_OBFUSCATED_FUNC(ret, name, ...) \ 27 | LIMBO_NOINLINE ret LIMBO_CAT(name, __LINE__)(__VA_ARGS__); \ 28 | _LIMBO_OBFUSCATED_BODY(name) \ 29 | LIMBO_NOINLINE ret LIMBO_CAT(name, __LINE__)(__VA_ARGS__) 30 | 31 | #define _LIMBO_OBFUSCATED_BODY(name) \ 32 | template \ 33 | LIMBO_NOINLINE decltype(auto) name(Args&&... args) { \ 34 | /* NOTE: This will fail and emit the original target address if the address isn't valid. */ \ 35 | constexpr std::uintptr_t key = limbo::rng::random_int<__COUNTER__>(-0x1000, 0x1000); \ 36 | /* NOTE: Addition is the only operation that didn't break this from my testing */ \ 37 | const std::uintptr_t shifted_addr = reinterpret_cast(&LIMBO_CAT(name, __LINE__)) + key; \ 38 | \ 39 | const auto loaded_addr = limbo::helpers::load_from_reg(shifted_addr); \ 40 | \ 41 | /* opaque predicate to hinder analysis TODO: better predicates */ \ 42 | const auto ret_addr = reinterpret_cast(_ReturnAddress()); \ 43 | \ 44 | const std::uintptr_t opaque_zero = limbo::emulation::XorR<5, LIMBO_RAND>(ret_addr, ret_addr); \ 45 | const std::uintptr_t opaque_key = limbo::emulation::AddR<5, LIMBO_RAND>(key, opaque_zero); \ 46 | \ 47 | /* calculate the correct target address */ \ 48 | const std::uintptr_t fixed_addr = limbo::emulation::SubR<5, LIMBO_RAND>(loaded_addr, opaque_key); \ 49 | \ 50 | const auto func = (decltype(LIMBO_CAT(name, __LINE__))*)(fixed_addr); \ 51 | return func(std::forward(args)...); \ 52 | }; 53 | #endif 54 | -------------------------------------------------------------------------------- /source/limbo/rng.h: -------------------------------------------------------------------------------- 1 | #pragma once 2 | 3 | /* 4 | * Copyright 2023 Ling 5 | * 6 | * Licensed under the Apache License, Version 2.0 (the "License"); 7 | * you may not use this file except in compliance with the License. 8 | * You may obtain a copy of the License at 9 | * 10 | * http://www.apache.org/licenses/LICENSE-2.0 11 | * 12 | * Unless required by applicable law or agreed to in writing, software 13 | * distributed under the License is distributed on an "AS IS" BASIS, 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | * See the License for the specific language governing permissions and 16 | * limitations under the License. 17 | */ 18 | 19 | #include 20 | #include 21 | 22 | namespace limbo 23 | { 24 | // 25 | // This namespace implements compile-time random number generation. 26 | // We use the compilation timestamp as a seed for xorshift 27 | // https://en.wikipedia.org/wiki/Xorshift 28 | // 29 | namespace rng 30 | { 31 | // 512 is the max recursion depth 32 | constexpr auto max_depth = 448; 33 | 34 | constexpr auto time = __TIME__; 35 | constexpr auto seed = static_cast(time[7]) + static_cast(time[6]) * 10 + static_cast(time[4]) * 60 + static_cast(time[3]) * 600 + static_cast(time[1]) * 3600 + static_cast(time[0]) * 36000; 36 | 37 | template 38 | LIMBO_FORCEINLINE constexpr std::uint64_t xorshift() 39 | { 40 | constexpr std::uint64_t s = xorshift(); 41 | constexpr std::uint64_t x1 = s ^ (s >> 12); 42 | constexpr std::uint64_t x2 = x1 ^ (x1 << 25); 43 | constexpr std::uint64_t x3 = x2 ^ (x2 >> 27); 44 | 45 | return x3 * 0x2545F4914F6CDD1DULL; 46 | } 47 | 48 | template <> 49 | LIMBO_FORCEINLINE constexpr std::uint64_t xorshift<0>() 50 | { 51 | constexpr std::uint64_t x1 = seed ^ (seed >> 12); 52 | constexpr std::uint64_t x2 = x1 ^ (x1 << 25); 53 | constexpr std::uint64_t x3 = x2 ^ (x2 >> 27); 54 | 55 | return x3 * 0x2545F4914F6CDD1DULL; 56 | } 57 | 58 | // Returns a random uint64_t in range of [0, max] 59 | template 60 | LIMBO_FORCEINLINE constexpr std::uint64_t random_int(std::uint64_t max = (std::numeric_limits::max)()) 61 | { 62 | return xorshift() % max; 63 | } 64 | 65 | // Returns a random uint64_t in range of [min, max] 66 | template 67 | LIMBO_FORCEINLINE constexpr std::uint64_t random_int(std::uint64_t min, std::uint64_t max) 68 | { 69 | return min + random_int(max - min - 1); 70 | } 71 | } 72 | } 73 | -------------------------------------------------------------------------------- /source/main.cpp: -------------------------------------------------------------------------------- 1 | 2 | #include 3 | 4 | #include "limbo.h" 5 | 6 | 7 | struct TestStruct 8 | { 9 | int a; 10 | }; 11 | 12 | LIMBO_OBFUSCATED_FUNC(int, obf_test, TestStruct struct_) 13 | { 14 | printf("[obf_test] Argument: %d\n", struct_.a); 15 | 16 | return struct_.a + 5; 17 | } 18 | 19 | 20 | int main(int argc, char* argv[]) 21 | { 22 | printf("[main] Starting...\n"); 23 | 24 | TestStruct emu {}; 25 | emu.a = 522; 26 | 27 | const auto ret = obf_test(emu); 28 | printf("[main] Received: %d\n", ret); 29 | 30 | return 0; 31 | } 32 | --------------------------------------------------------------------------------