diff options
Diffstat (limited to 'NorthstarDLL/exploitfixes.cpp')
| -rw-r--r-- | NorthstarDLL/exploitfixes.cpp | 553 |
1 files changed, 553 insertions, 0 deletions
diff --git a/NorthstarDLL/exploitfixes.cpp b/NorthstarDLL/exploitfixes.cpp new file mode 100644 index 00000000..aa5adae3 --- /dev/null +++ b/NorthstarDLL/exploitfixes.cpp @@ -0,0 +1,553 @@ +#include "pch.h" + +#include "exploitfixes.h" +#include "exploitfixes_utf8parser.h" +#include "nsmem.h" +#include "cvar.h" +#include "gameutils.h" + +ConVar* ns_exploitfixes_log; +#define SHOULD_LOG (ns_exploitfixes_log->m_Value.m_nValue > 0) +#define BLOCKED_INFO(s) \ + ( \ + [=]() -> bool \ + { \ + if (SHOULD_LOG) \ + { \ + std::stringstream stream; \ + stream << "exploitfixes.cpp: " << BLOCK_PREFIX << s; \ + spdlog::error(stream.str()); \ + } \ + return false; \ + }()) + +struct Float3 +{ + float vals[3]; + + void MakeValid() + { + for (auto& val : vals) + if (isnan(val)) + val = 0; + } +}; + +#define BLOCK_NETMSG_FUNC(name, pattern) \ + KHOOK(name, ("engine.dll", pattern), bool, __fastcall, (void* thisptr, void* buffer)) \ + { \ + return false; \ + } + +// Servers can literally request a screenshot from any client, yeah no +BLOCK_NETMSG_FUNC(CLC_Screenshot_WriteToBuffer, "48 89 5C 24 ? 57 48 83 EC 20 8B 42 10"); +BLOCK_NETMSG_FUNC(CLC_Screenshot_ReadFromBuffer, "48 89 5C 24 ? 48 89 6C 24 ? 48 89 74 24 ? 57 48 83 EC 20 48 8B DA 48 8B 52 38"); + +// This is unused ingame and a big exploit vector +BLOCK_NETMSG_FUNC(Base_CmdKeyValues_ReadFromBuffer, "40 55 48 81 EC ? ? ? ? 48 8D 6C 24 ? 48 89 5D 70"); + +KHOOK(CClient_ProcessSetConVar, ("engine.dll", "48 8B D1 48 8B 49 18 48 8B 01 48 FF 60 10"), bool, __fastcall, (void* pMsg)) +{ + + constexpr int ENTRY_STR_LEN = 260; + struct SetConVarEntry + { + char name[ENTRY_STR_LEN]; + char val[ENTRY_STR_LEN]; + }; + + struct NET_SetConVar + { + void* vtable; + void* unk1; + void* unk2; + void* m_pMessageHandler; + SetConVarEntry* m_ConVars; // convar entry array + void* unk5; // these 2 unks are just vector capacity or whatever + void* unk6; + int m_ConVars_count; // amount of cvar entries in array (this will not be out of bounds) + }; + + auto msg = (NET_SetConVar*)pMsg; + + bool areWeServer; + + { + // Figure out of we are the client or the server + // To do this, we utilize the msg's m_pMessageHandler pointer + // m_pMessageHandler points to a virtual class that handles all net messages + // The first virtual table function of our m_pMessageHandler will differ if it is IServerMessageHandler or IClientMessageHandler + void* msgHandlerVTableFirstFunc = **(void****)(msg->m_pMessageHandler); + static auto engineBaseAddress = (uintptr_t)GetModuleHandleA("engine.dll"); + auto offset = uintptr_t(msgHandlerVTableFirstFunc) - engineBaseAddress; + + constexpr uintptr_t CLIENTSTATE_FIRST_VFUNC_OFFSET = 0x8A15C; + areWeServer = offset != CLIENTSTATE_FIRST_VFUNC_OFFSET; + } + + std::string BLOCK_PREFIX = std::string {"NET_SetConVar ("} + (areWeServer ? "server" : "client") + "): Blocked dangerous/invalid msg: "; + + if (areWeServer) + { + constexpr int SETCONVAR_SANITY_AMOUNT_LIMIT = 69; + if (msg->m_ConVars_count < 1 || msg->m_ConVars_count > SETCONVAR_SANITY_AMOUNT_LIMIT) + { + return BLOCKED_INFO("Invalid m_ConVars_count (" << msg->m_ConVars_count << ")"); + } + } + + for (int i = 0; i < msg->m_ConVars_count; i++) + { + auto entry = msg->m_ConVars + i; + + // Safety check for memory access + if (NSMem::IsMemoryReadable(entry, sizeof(*entry))) + { + + // Find null terminators + bool nameValid = false, valValid = false; + for (int i = 0; i < ENTRY_STR_LEN; i++) + { + if (!entry->name[i]) + nameValid = true; + if (!entry->val[i]) + valValid = true; + } + + if (!nameValid || !valValid) + return BLOCKED_INFO("Missing null terminators"); + + auto realVar = g_pCVar->FindVar(entry->name); + + if (realVar) + memcpy( + entry->name, + realVar->m_ConCommandBase.m_pszName, + strlen(realVar->m_ConCommandBase.m_pszName) + 1); // Force name to match case + + bool isValidFlags = true; + if (areWeServer) + { + if (realVar) + isValidFlags = ConVar::IsFlagSet(realVar, FCVAR_USERINFO); // ConVar MUST be userinfo var + } + else + { + // TODO: Should probably have some sanity checks, but can't find any that are consistent + } + + if (!isValidFlags) + { + if (!realVar) + { + return BLOCKED_INFO("Invalid flags on nonexistant cvar (how tho???)"); + } + else + { + return BLOCKED_INFO( + "Invalid flags (" << std::hex << "0x" << realVar->m_ConCommandBase.m_nFlags << "), var is " << entry->name); + } + } + } + else + { + return BLOCKED_INFO("Unreadable memory at " << (void*)entry); // Not risking that one, they all gotta be readable + } + } + + return oCClient_ProcessSetConVar(msg); +} + +// Purpose: prevent invalid user CMDs +KHOOK(CClient_ProcessUsercmds, ("engine.dll", "40 55 56 48 83 EC 58"), bool, __fastcall, (void* thisptr, void* pMsg)) +{ + struct CLC_Move + { + BYTE gap0[24]; + void* m_pMessageHandler; + int m_nBackupCommands; + int m_nNewCommands; + int m_nLength; + // bf_read m_DataIn; + // bf_write m_DataOut; + }; + + auto msg = (CLC_Move*)pMsg; + + const char* BLOCK_PREFIX = "ProcessUserCmds: "; + + if (msg->m_nBackupCommands < 0) + { + return BLOCKED_INFO("Invalid m_nBackupCommands (" << msg->m_nBackupCommands << ")"); + } + + if (msg->m_nNewCommands < 0) + { + return BLOCKED_INFO("Invalid m_nNewCommands (" << msg->m_nNewCommands << ")"); + } + + constexpr int NUMCMD_SANITY_LIMIT = 16; + if ((msg->m_nNewCommands + msg->m_nBackupCommands) > NUMCMD_SANITY_LIMIT) + { + return BLOCKED_INFO("Command count is too high (new: " << msg->m_nNewCommands << ", backup: " << msg->m_nBackupCommands << ")"); + } + + if (msg->m_nLength <= 0) + return BLOCKED_INFO("Invalid message length (" << msg->m_nLength << ")"); + + return oCClient_ProcessUsercmds(thisptr, pMsg); +} + +KHOOK(ReadUsercmd, ("server.dll", "4C 89 44 24 ? 53 55 56 57"), void, __fastcall, (void* buf, void* pCmd_move, void* pCmd_from)) +{ + // Let normal usercmd read happen first, it's safe + oReadUsercmd(buf, pCmd_move, pCmd_from); + + // Now let's make sure the CMD we read isnt messed up to prevent numerous exploits (including server crashing) + struct alignas(4) SV_CUserCmd + { + DWORD command_number; + DWORD tick_count; + float command_time; + Float3 worldViewAngles; + BYTE gap18[4]; + Float3 localViewAngles; + Float3 attackangles; + Float3 move; + DWORD buttons; + BYTE impulse; + short weaponselect; + DWORD meleetarget; + BYTE gap4C[24]; + char headoffset; + BYTE gap65[11]; + Float3 cameraPos; + Float3 cameraAngles; + BYTE gap88[4]; + int tickSomething; + DWORD dword90; + DWORD predictedServerEventAck; + DWORD dword98; + float frameTime; + }; + + auto cmd = (SV_CUserCmd*)pCmd_move; + auto fromCmd = (SV_CUserCmd*)pCmd_from; + + std::string BLOCK_PREFIX = + "ReadUsercmd (command_number delta: " + std::to_string(cmd->command_number - fromCmd->command_number) + "): "; + + // Fix invalid player angles + cmd->worldViewAngles.MakeValid(); + cmd->attackangles.MakeValid(); + cmd->localViewAngles.MakeValid(); + + // Fix invalid camera angles + cmd->cameraPos.MakeValid(); + cmd->cameraAngles.MakeValid(); + + // Fix invaid movement vector + cmd->move.MakeValid(); + + if (cmd->tick_count == 0 || cmd->command_time <= 0) + { + BLOCKED_INFO( + "Bogus cmd timing (tick_count: " << cmd->tick_count << ", frameTime: " << cmd->frameTime + << ", commandTime : " << cmd->command_time << ")"); + goto INVALID_CMD; // No simulation of bogus-timed cmds + } + + return; + +INVALID_CMD: + // Fix any gameplay-affecting cmd properties + // NOTE: Currently tickcount/frametime is set to 0, this ~shouldn't~ cause any problems + cmd->worldViewAngles = cmd->localViewAngles = cmd->attackangles = cmd->cameraAngles = {0, 0, 0}; + cmd->tick_count = cmd->frameTime = 0; + cmd->move = cmd->cameraPos = {0, 0, 0}; + cmd->buttons = 0; + cmd->meleetarget = 0; +} + +// basically: by default r2 isn't set as a valve mod, meaning that m_bRestrictServerCommands is false +// this is HORRIBLE for security, because it means servers can run arbitrary concommands on clients +// especially since we have script commands this could theoretically be awful +KHOOK(IsValveMod, ("engine.dll", "48 83 EC 28 48 8B 0D ? ? ? ? 48 8D 15 ? ? ? ? E8 ? ? ? ? 85 C0 74 63"), bool, __fastcall, ()) +{ + bool result = !CommandLine()->CheckParm("-norestrictservercommands"); + spdlog::info("ExploitFixes: Overriding IsValveMod to {}...", result); + return result; +} + +// Fix respawn's crappy UTF8 parser so it doesn't crash -_- +// This also means you can launch multiplayer with "communities_enabled 1" and not crash, you're welcome +KHOOK( + CrashFunc_ParseUTF8, + ("engine.dll", "48 89 5C 24 ? 48 89 6C 24 ? 48 89 74 24 ? 57 41 54 41 55 41 56 41 57 48 83 EC 20 8B 1A"), + bool, + __fastcall, + (INT64 * a1, DWORD* a2, char* strData)) +{ + + static void* targetRetAddr = NSMem::PatternScan("engine.dll", "84 C0 75 2C 49 8B 16"); + +#ifdef _MSC_VER + if (_ReturnAddress() == targetRetAddr) +#else + if (__builtin_return_address(0) == targetRetAddr) +#endif + { + if (!ExploitFixes_UTF8Parser::CheckValid(a1, a2, strData)) + { + const char* BLOCK_PREFIX = "ParseUTF8 Hook: "; + BLOCKED_INFO("Ignoring potentially-crashing utf8 string"); + return false; + } + } + + return oCrashFunc_ParseUTF8(a1, a2, strData); +} + +// GetEntByIndex (called by ScriptGetEntByIndex) doesn't check for the index being out of bounds when it's +// above the max entity count. This allows it to be used to crash servers. +typedef void*(__fastcall* GetEntByIndexType)(int idx); +GetEntByIndexType GetEntByIndex; + +static void* GetEntByIndexHook(int idx) +{ + if (idx >= 0x4000) + { + spdlog::info("GetEntByIndex {} is out of bounds", idx); + return nullptr; + } + return GetEntByIndex(idx); +} + +// RELOCATED FROM https://github.com/R2Northstar/NorthstarLauncher/commit/25dbf729cfc75107a0fcf0186924b58ecc05214b +// Rewrite of CLZSS::SafeUncompress to fix a vulnerability where malicious compressed payloads could cause the decompressor to try to read +// out of the bounds of the output buffer. +KHOOK( + LZSS_SafeUncompress, + ("engine.dll", "48 89 5C 24 ? 48 89 6C 24 ? 48 89 74 24 ? 48 89 7C 24 ? 33 ED 41 8B F9"), + uint32_t, + __fastcall, + (void* self, const unsigned char* pInput, unsigned char* pOutput, unsigned int unBufSize)) +{ + static constexpr int LZSS_LOOKSHIFT = 4; + + uint32_t totalBytes = 0; + int getCmdByte = 0, cmdByte = 0; + + struct lzss_header_t + { + uint32_t id, actualSize; + }; + + lzss_header_t header = *(lzss_header_t*)pInput; + + if (pInput == NULL || header.id != 'SSZL' || header.actualSize == 0 || header.actualSize > unBufSize) + return 0; + + pInput += sizeof(lzss_header_t); + + for (;;) + { + if (!getCmdByte) + cmdByte = *pInput++; + + getCmdByte = (getCmdByte + 1) & 0x07; + + if (cmdByte & 0x01) + { + int position = *pInput++ << LZSS_LOOKSHIFT; + position |= (*pInput >> LZSS_LOOKSHIFT); + position += 1; + + int count = (*pInput++ & 0x0F) + 1; + if (count == 1) + break; + + // Ensure reference chunk exists entirely within our buffer + if (position > totalBytes) + return 0; + + totalBytes += count; + if (totalBytes > unBufSize) + return 0; + + unsigned char* pSource = pOutput - position; + for (int i = 0; i < count; i++) + *pOutput++ = *pSource++; + } + else + { + totalBytes++; + if (totalBytes > unBufSize) + return 0; + + *pOutput++ = *pInput++; + } + cmdByte = cmdByte >> 1; + } + + if (totalBytes == header.actualSize) + { + return totalBytes; + } + else + { + return 0; + } +} + +////////////////////////////////////////////////// + +void DoBytePatches() +{ + uintptr_t engineBase = (uintptr_t)GetModuleHandleA("engine.dll"); + uintptr_t serverBase = (uintptr_t)GetModuleHandleA("server.dll"); + + // patches to make commands run from client/ui script still work + // note: this is likely preventable in a nicer way? test prolly + NSMem::BytePatch(engineBase + 0x4FB65, "EB 11"); + NSMem::BytePatch(engineBase + 0x4FBAC, "EB 16"); + + // disconnect concommand + { + uintptr_t addr = engineBase + 0x5ADA2D; + int val = *(int*)addr | FCVAR_SERVER_CAN_EXECUTE; + NSMem::BytePatch(addr, (BYTE*)&val, sizeof(int)); + } + + { // Dumb ANTITAMPER patches (they negatively impact performance and security) + + constexpr const char* ANTITAMPER_EXPORTS[] = { + "ANTITAMPER_SPOTCHECK_CODEMARKER", + "ANTITAMPER_TESTVALUE_CODEMARKER", + "ANTITAMPER_TRIGGER_CODEMARKER", + }; + + // Prevent thesefrom actually doing anything + for (auto exportName : ANTITAMPER_EXPORTS) + { + + auto address = (uintptr_t)GetProcAddress(GetModuleHandleA("server.dll"), exportName); + if (!address) + { + spdlog::warn("Failed to find AntiTamper function export \"{}\"", exportName); + } + else + { + // Just return, none of them have any args or are userpurge + NSMem::BytePatch(address, "C3"); + + spdlog::info("Patched AntiTamper function export \"{}\"", exportName); + } + } + } +} + +KHOOK( + SpecialClientCommand, + ("server.dll", "48 89 5C 24 ? 48 89 74 24 ? 55 57 41 56 48 8D 6C 24 ? 48 81 EC ? ? ? ? 83 3A 00"), + bool, + __fastcall, + (void* player, CCommand* command)) +{ + + static ConVar* sv_cheats = g_pCVar->FindVar("sv_cheats"); + + if (sv_cheats->GetBool()) + return oSpecialClientCommand(player, command); // Don't block anything if sv_cheats is on + + // These are mostly from Portal 2 (sigh) + constexpr const char* blockedCommands[] = { + "emit", // Sound-playing exploit (likely for Portal 2 coop devs testing splitscreen sound or something) + + // These both execute a command for every single entity for some reason, nice one valve + "pre_go_to_hub", + "pre_go_to_calibration", + + "end_movie", // Calls "__MovieFinished" script function, not sure exactly what this does but it certainly isn't needed + "load_recent_checkpoint" // This is the instant-respawn exploit, literally just calls RespawnPlayer() + }; + + if (command->ArgC() > 0) + { + std::string cmdStr = command->Arg(0); + for (char& c : cmdStr) + c = tolower(c); + + for (const char* blockedCommand : blockedCommands) + { + if (cmdStr.find(blockedCommand) != std::string::npos) + { + // Block this command + spdlog::warn("Blocked exploititive client command \"{}\".", cmdStr); + return true; + } + } + } + + return oSpecialClientCommand(player, command); +} + +void SetupKHook(KHook* hook) +{ + if (hook->Setup()) + { + spdlog::debug("KHook::Setup(): Hooked at {}", hook->targetFuncAddr); + } + else + { + spdlog::critical("\tFAILED to initialize all exploit patches."); + + // Force exit + MessageBoxA(0, "FAILED to initialize all exploit patches.", "Northstar", MB_ICONERROR); + exit(0); + } +} + +void ExploitFixes::LoadCallback_MultiModule(HMODULE baseAddress) +{ + + spdlog::info("ExploitFixes::LoadCallback_MultiModule({}) ...", (void*)baseAddress); + + int hooksEnabled = 0; + for (auto itr = KHook::_allHooks.begin(); itr != KHook::_allHooks.end(); itr++) + { + auto curHook = *itr; + if (GetModuleHandleA(curHook->targetFunc.moduleName) == baseAddress) + { + SetupKHook(curHook); + itr = KHook::_allHooks.erase(itr); // Prevent repeated initialization + + hooksEnabled++; + + if (itr == KHook::_allHooks.end()) + break; + } + } + + spdlog::info("\tEnabled {} hooks.", hooksEnabled); +} + +void ExploitFixes::LoadCallback_Full(HMODULE baseAddress) +{ + spdlog::info("ExploitFixes::LoadCallback_Full ..."); + + spdlog::info("\tByte patching..."); + DoBytePatches(); + + for (KHook* hook : KHook::_allHooks) + SetupKHook(hook); + + spdlog::info("\tInitialized " + std::to_string(KHook::_allHooks.size()) + " late exploit-patch hooks."); + KHook::_allHooks.clear(); + + ns_exploitfixes_log = + new ConVar("ns_exploitfixes_log", "1", FCVAR_GAMEDLL, "Whether to log whenever exploitfixes.cpp blocks/corrects something"); + + HookEnabler hook; + ENABLER_CREATEHOOK(hook, (char*)baseAddress + 0x2a8a50, &GetEntByIndexHook, reinterpret_cast<LPVOID*>(&GetEntByIndex)); +} |