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AUTOHOOK_INIT()
INT64(__fastcall* sub_F1320)(DWORD a1, char* a2);
// Reimplementation of an exploitable UTF decoding function in titanfall
bool __fastcall CheckUTF8Valid(INT64* a1, DWORD* a2, char* strData)
{
DWORD v3; // eax
char* v4; // rbx
char v5; // si
char* _strData; // rdi
char* v7; // rbp
char v11; // al
DWORD v12; // er9
DWORD v13; // ecx
DWORD v14; // edx
DWORD v15; // er8
int v16; // eax
DWORD v17; // er9
int v18; // eax
DWORD v19; // er9
DWORD v20; // ecx
int v21; // eax
int v22; // er9
DWORD v23; // edx
int v24; // eax
int v25; // er9
DWORD v26; // er9
DWORD v27; // er10
DWORD v28; // ecx
DWORD v29; // edx
DWORD v30; // er8
int v31; // eax
DWORD v32; // er10
int v33; // eax
DWORD v34; // er10
DWORD v35; // ecx
int v36; // eax
int v37; // er10
DWORD v38; // edx
int v39; // eax
int v40; // er10
DWORD v41; // er10
INT64 v43; // r8
INT64 v44; // rdx
INT64 v45; // rcx
INT64 v46; // rax
INT64 v47; // rax
char v48; // al
INT64 v49; // r8
INT64 v50; // rdx
INT64 v51; // rcx
INT64 v52; // rax
INT64 v53; // rax
v3 = a2[2];
v4 = (char*)(a1[1] + *a2);
v5 = 0;
_strData = strData;
v7 = &v4[*((UINT16*)a2 + 2)];
if (v3 >= 2)
{
++v4;
--v7;
if (v3 != 2)
{
while (1)
{
if (!CMemoryAddress(v4).IsMemoryReadable(1))
return false; // INVALID
v11 = *v4++; // crash potential
if (v11 != 92)
goto LABEL_6;
v11 = *v4++;
if (v11 == 110)
break;
switch (v11)
{
case 't':
v11 = 9;
goto LABEL_6;
case 'r':
v11 = 13;
goto LABEL_6;
case 'b':
v11 = 8;
goto LABEL_6;
case 'f':
v11 = 12;
goto LABEL_6;
}
if (v11 != 117)
goto LABEL_6;
v12 = *v4 | 0x20;
v13 = v4[1] | 0x20;
v14 = v4[2] | 0x20;
v15 = v4[3] | 0x20;
v16 = 87;
if (v12 <= 0x39)
v16 = 48;
v17 = v12 - v16;
v18 = 87;
v19 = v17 << 12;
if (v13 <= 0x39)
v18 = 48;
v20 = v13 - v18;
v21 = 87;
v22 = (v20 << 8) | v19;
if (v14 <= 0x39)
v21 = 48;
v23 = v14 - v21;
v24 = 87;
v25 = (16 * v23) | v22;
if (v15 <= 0x39)
v24 = 48;
v4 += 4;
v26 = (v15 - v24) | v25;
if (v26 - 55296 <= 0x7FF)
{
if (v26 >= 0xDC00)
return true;
if (*v4 != 92 || v4[1] != 117)
return true;
v27 = v4[2] | 0x20;
v28 = v4[3] | 0x20;
v29 = v4[4] | 0x20;
v30 = v4[5] | 0x20;
v31 = 87;
if (v27 <= 0x39)
v31 = 48;
v32 = v27 - v31;
v33 = 87;
v34 = v32 << 12;
if (v28 <= 0x39)
v33 = 48;
v35 = v28 - v33;
v36 = 87;
v37 = (v35 << 8) | v34;
if (v29 <= 0x39)
v36 = 48;
v38 = v29 - v36;
v39 = 87;
v40 = (16 * v38) | v37;
if (v30 <= 0x39)
v39 = 48;
v4 += 6;
v41 = ((v30 - v39) | v40) - 56320;
if (v41 > 0x3FF)
return true;
v26 = v41 | ((v26 - 55296) << 10);
}
_strData += (DWORD)sub_F1320(v26, _strData);
LABEL_7:
if (v4 == v7)
goto LABEL_48;
}
v11 = 10;
LABEL_6:
v5 |= v11;
*_strData++ = v11;
goto LABEL_7;
}
}
LABEL_48:
return true;
}
// prevent utf8 parser from crashing when provided bad data, which can be sent through user-controlled openinvites
// clang-format off
AUTOHOOK(Rson_ParseUTF8, engine.dll + 0xEF670,
bool, __fastcall, (INT64* a1, DWORD* a2, char* strData)) // 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
// clang-format on
{
static void* targetRetAddr = CModule("engine.dll").FindPattern("84 C0 75 2C 49 8B 16");
// only call if we're parsing utf8 data from the network (i.e. communities), otherwise we get perf issues
void* pReturnAddress =
#ifdef _MSC_VER
_ReturnAddress()
#else
__builtin_return_address(0)
#endif
;
if (pReturnAddress == targetRetAddr && !CheckUTF8Valid(a1, a2, strData))
return false;
return Rson_ParseUTF8(a1, a2, strData);
}
ON_DLL_LOAD("engine.dll", EngineExploitFixes_UTF8Parser, (CModule module))
{
AUTOHOOK_DISPATCH()
sub_F1320 = module.FindPattern("83 F9 7F 77 08 88 0A").RCast<INT64(__fastcall*)(DWORD, char*)>();
}
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