aboutsummaryrefslogtreecommitdiff
path: root/NorthstarDedicatedTest/ExploitFixes.cpp
blob: 277475f6c84fd5ebd9f67d039d65375d1b29d231 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
#include "pch.h"

#include "ExploitFixes.h"
#include "ExploitFixes_UTF8Parser.h"
#include "NSMem.h"
#include "cvar.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;                                                                                                                  \
		}())

// Make sure 3 or less floats are valid
bool ValidateFloats(float a, float b = 0, float c = 0)
{
	return !isnan(a) && !isnan(b) && !isnan(c);
}

struct Vector
{
	float x, y, z;

	Vector(float x = 0, float y = 0, float z = 0) : x(x), y(y), z(z) {}

	bool IsValid()
	{
		return ValidateFloats(x, y, z);
	}
};

struct Angle
{
	float pitch, yaw, roll;

	Angle(float pitch = 0, float yaw = 0, float roll = 0) : pitch(pitch), yaw(yaw), roll(roll) {}

	bool IsInvalid()
	{
		if (!ValidateFloats(pitch, yaw, roll))
			return false;

		return (pitch > 90 || pitch < -90) || (yaw > 180 || yaw < -180) || (roll > 180 || roll < -180);
	}
};

#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 __declspec(align(4)) SV_CUserCmd
	{
		DWORD command_number;
		DWORD tick_count;
		float command_time;
		Angle worldViewAngles;
		BYTE gap18[4];
		Angle localViewAngles;
		Angle attackangles;
		Vector move;
		DWORD buttons;
		BYTE impulse;
		short weaponselect;
		DWORD meleetarget;
		BYTE gap4C[24];
		char headoffset;
		BYTE gap65[11];
		Vector cameraPos;
		Angle 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) + "): ";

	if (cmd->worldViewAngles.IsInvalid())
	{
		BLOCKED_INFO("CMD has invalid worldViewAngles");
		goto INVALID_CMD;
	}

	if (cmd->attackangles.IsInvalid())
	{
		BLOCKED_INFO("CMD has invalid attackangles");
		goto INVALID_CMD;
	}

	if (cmd->localViewAngles.IsInvalid())
	{
		BLOCKED_INFO("CMD has invalid localViewAngles");
		goto INVALID_CMD;
	}

	if (cmd->cameraAngles.IsInvalid())
	{
		BLOCKED_INFO("CMD has invalid cameraAngles");
		goto INVALID_CMD;
	}

	if (cmd->frameTime <= 0 || 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
	}

	if (!cmd->move.IsValid())
	{
		BLOCKED_INFO("Invalid move vector");
		goto INVALID_CMD;
	}

	if (!cmd->cameraPos.IsValid())
	{
		BLOCKED_INFO("Invalid cameraPos"); // IIRC this can crash spectating clients or anyone watching replays
		goto INVALID_CMD;
	}

	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 = Angle(0, 0, 0);
	cmd->tick_count = cmd->frameTime = 0;
	cmd->move = cmd->cameraPos = Vector(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
#include "gameutils.h"
KHOOK(IsValveMod, ("engine.dll", "48 83 EC 28 48 8B 0D ? ? ? ? 48 8D 15 ? ? ? ? E8 ? ? ? ? 85 C0 74 63"), bool, __fastcall, ())
{
	return !CommandLine()->CheckParm("-norestrictservercommands");
}

// 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");

	if (_ReturnAddress() == targetRetAddr)
	{
		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);
}

//////////////////////////////////////////////////

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);
			}
		}
	}
}

void ExploitFixes::LoadCallback(HMODULE baseAddress)
{
	spdlog::info("ExploitFixes::LoadCallback ...");

	spdlog::info("\tByte patching...");
	DoBytePatches();

	if (KHook::InitAllHooks())
	{
		spdlog::info("\tInitialized " + std::to_string(KHook::_allHooks.size()) + " exploit-patch hooks.");
	}
	else
	{
		spdlog::critical("\tFAILED to initialize all exploit patches.");

		// Force exit?
		MessageBoxA(0, "FAILED to initialize all exploit patches.", "Northstar", MB_ICONERROR);
		exit(0);
	}

	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));
}