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312 lines
7.9 KiB
312 lines
7.9 KiB
#include "RipXorInst.h"
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BOOL ObfEmitPushfqInst(PNATIVE_CODE_BLOCK Block)
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{
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UCHAR RawData[] = { 0x9C };
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PNATIVE_CODE_LINK Link = new NATIVE_CODE_LINK(CODE_FLAG_IS_INST, RawData, 1);
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XedDecode(&Link->XedInst, Link->RawData, 1);
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NcAppendToBlock(Block, Link);
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return TRUE;
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}
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BOOL ObfEmitPopfqInst(PNATIVE_CODE_BLOCK Block)
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{
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UCHAR RawData[] = { 0x9D };
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PNATIVE_CODE_LINK Link = new NATIVE_CODE_LINK(CODE_FLAG_IS_INST, RawData, 1);
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XedDecode(&Link->XedInst, Link->RawData, 1);
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NcAppendToBlock(Block, Link);
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return TRUE;
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}
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BOOL ObfEmitRipRelativeXorD(PNATIVE_CODE_BLOCK Block, INT32 RipDelta, ULONG Value)
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{
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UCHAR RawData[] = { 0x81, 0x35, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
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PNATIVE_CODE_LINK Link = new NATIVE_CODE_LINK(CODE_FLAG_IS_INST, RawData, sizeof(RawData));
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*(PINT32)&Link->RawData[DWORD_XOR_INST_RIP_OFFSET] = RipDelta;
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*(PULONG)&Link->RawData[DWORD_XOR_INST_XOR_OFFSET] = Value;
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XedDecode(&Link->XedInst, Link->RawData, Link->RawDataSize);
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NcAppendToBlock(Block, Link);
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return TRUE;
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}
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BOOL ObfEmitRipRelativeXorW(PNATIVE_CODE_BLOCK Block, INT32 RipDelta, ULONG Value)
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{
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UCHAR RawData[] = { 0x66, 0x81, 0x35, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
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PNATIVE_CODE_LINK Link = new NATIVE_CODE_LINK(CODE_FLAG_IS_INST, RawData, sizeof(RawData));
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*(PINT32)&Link->RawData[WORD_XOR_INST_RIP_OFFSET] = RipDelta;
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*(PUSHORT)&Link->RawData[WORD_XOR_INST_XOR_OFFSET] = (USHORT)Value;
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XedDecode(&Link->XedInst, Link->RawData, Link->RawDataSize);
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NcAppendToBlock(Block, Link);
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return TRUE;
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}
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BOOL ObfEmitRipRelativeXorB(PNATIVE_CODE_BLOCK Block, INT32 RipDelta, ULONG Value)
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{
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UCHAR RawData[] = { 0x80, 0x35, 0x00, 0x00, 0x00, 0x00, 0x00 };
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PNATIVE_CODE_LINK Link = new NATIVE_CODE_LINK(CODE_FLAG_IS_INST, RawData, sizeof(RawData));
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*(PINT32)&Link->RawData[BYTE_XOR_INST_RIP_OFFSET] = RipDelta;
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*(PUCHAR)&Link->RawData[BYTE_XOR_INST_XOR_OFFSET] = (UCHAR)Value;
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XedDecode(&Link->XedInst, Link->RawData, Link->RawDataSize);
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NcAppendToBlock(Block, Link);
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return TRUE;
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}
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VOID ObfXorInstBytes(PNATIVE_CODE_LINK Link, PXOR_INST_DATA XorData)
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{
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ULONG FourByte = Link->RawDataSize / 4;
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ULONG TwoByte = (Link->RawDataSize - (FourByte * 4)) / 2;
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ULONG OneByte = (Link->RawDataSize - (FourByte * 4) - (TwoByte * 2));
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PUCHAR Buffer = Link->RawData;
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while (FourByte)
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{
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*(PULONG)Buffer ^= XorData->Data[2 - FourByte];
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Buffer += 4;
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FourByte--;
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}
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if (TwoByte)
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{
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*(PUSHORT)Buffer ^= (USHORT)XorData->Data[3];
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Buffer += 2;
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}
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if (OneByte)
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*(PUCHAR)Buffer ^= (UCHAR)XorData->Data[3];
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}
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BOOL ObfiCheckXorFlagCollisions(CONST XED_FLAG_SET* FlagsRead, XED_FLAG_SET Ledger)
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{
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return ((FlagsRead->s.zf && FlagsRead->s.zf == Ledger.s.zf) ||
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(FlagsRead->s.sf && FlagsRead->s.sf == Ledger.s.sf) ||
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(FlagsRead->s.pf && FlagsRead->s.pf == Ledger.s.pf) ||
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(FlagsRead->s.of && FlagsRead->s.of == Ledger.s.of) ||
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(FlagsRead->s.cf && FlagsRead->s.cf == Ledger.s.cf) ||
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(FlagsRead->s.af && FlagsRead->s.af == Ledger.s.af)
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);
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}
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VOID ObfiUpdateXorLedger(CONST XED_FLAG_SET* FlagsWritten, XED_FLAG_SET* Ledger)
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{
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if (FlagsWritten->s.zf)
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Ledger->s.zf = FALSE;
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if (FlagsWritten->s.sf)
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Ledger->s.sf = FALSE;
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if (FlagsWritten->s.pf)
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Ledger->s.pf = FALSE;
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if (FlagsWritten->s.of)
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Ledger->s.of = FALSE;
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if (FlagsWritten->s.cf)
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Ledger->s.cf = FALSE;
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if (FlagsWritten->s.af)
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Ledger->s.af = FALSE;
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}
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BOOL ObfDoesInstWriteToAllXorFlags(PNATIVE_CODE_LINK Link)
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{
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CONST XED_SIMPLE_FLAG* SimpleFlags = XedDecodedInstGetRflagsInfo(&Link->XedInst);
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CONST XED_FLAG_SET* FlagsWritten = XedSimpleFlagGetWrittenFlagSet(SimpleFlags);
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CONST XED_FLAG_SET* FlagsUndefined = XedSimpleFlagGetUndefinedFlagSet(SimpleFlags);
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return (FlagsWritten->s.zf &&
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FlagsWritten->s.sf &&
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FlagsWritten->s.pf &&
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FlagsWritten->s.of &&
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FlagsWritten->s.cf &&
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FlagsUndefined->s.af
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);
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}
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BOOL ObfAreXorFlagsClobberedBeforeUse(PNATIVE_CODE_LINK Link)
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{
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XED_FLAG_SET Ledger;
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Ledger.s.zf = TRUE;
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Ledger.s.sf = TRUE;
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Ledger.s.pf = TRUE;
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Ledger.s.of = TRUE;
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Ledger.s.cf = TRUE;
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Ledger.s.af = TRUE;
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for (PNATIVE_CODE_LINK T = Link->Next; T; T = T->Next)
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{
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if (T->Flags & CODE_FLAG_IS_LABEL)
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continue;
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CONST XED_SIMPLE_FLAG* SimpleFlags = XedDecodedInstGetRflagsInfo(&T->XedInst);
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CONST XED_FLAG_SET* FlagsRead = XedSimpleFlagGetReadFlagSet(SimpleFlags);
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CONST XED_FLAG_SET* FlagsWritten = XedSimpleFlagGetWrittenFlagSet(SimpleFlags);
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if (ObfiCheckXorFlagCollisions(FlagsRead, Ledger))
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return FALSE;
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ObfiUpdateXorLedger(FlagsWritten, &Ledger);
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if (Ledger.flat == 0)
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return TRUE;
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}
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return FALSE;
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}
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PNATIVE_CODE_BLOCK ObfEmitPreXorForInst(PNATIVE_CODE_LINK Link, PXOR_INST_DATA XorData, BOOL SaveFlags, INT32 DeltaToInst)
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{
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ULONG FourByte = Link->RawDataSize / 4;
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ULONG TwoByte = (Link->RawDataSize - (FourByte * 4)) / 2;
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ULONG OneByte = (Link->RawDataSize - (FourByte * 4) - (TwoByte * 2));
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PNATIVE_CODE_BLOCK Block = new NATIVE_CODE_BLOCK;
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if (!Block)
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return NULL;
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if (SaveFlags && !ObfEmitPushfqInst(Block))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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ULONG Count = FourByte;
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while (Count)
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{
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//Account for remaining XORs
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INT32 RipDelta = (((Count - 1) * DWORD_XOR_INST_LENGTH) + (TwoByte * WORD_XOR_INST_LENGTH) + (OneByte * BYTE_XOR_INST_LENGTH));
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//Account for POPFQ
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if (SaveFlags)
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RipDelta += 1;
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//Account for already XORd instructions
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RipDelta += ((FourByte - Count) * 4);
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RipDelta += DeltaToInst;
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//Add the actual instruction
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if (!ObfEmitRipRelativeXorD(Block, RipDelta, XorData->Data[FourByte-Count]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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--Count;
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}
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if (TwoByte)
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{
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INT32 RipDelta = (OneByte * BYTE_XOR_INST_LENGTH);
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if (SaveFlags)
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RipDelta += 1;
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RipDelta += (FourByte * 4);
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RipDelta += DeltaToInst;
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if (!ObfEmitRipRelativeXorW(Block, RipDelta, XorData->Data[3]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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}
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if (OneByte)
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{
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INT32 RipDelta = 0;
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if (SaveFlags)
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RipDelta += 1;
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RipDelta += (FourByte * 4) + (TwoByte * 2);
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RipDelta += DeltaToInst;
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if (!ObfEmitRipRelativeXorB(Block, RipDelta, XorData->Data[4]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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}
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if (SaveFlags && !ObfEmitPopfqInst(Block))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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return Block;
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}
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PNATIVE_CODE_BLOCK ObfEmitPostXorForInst(PNATIVE_CODE_LINK Link, PXOR_INST_DATA XorData, BOOL SaveFlags, INT32 DeltaToInst)
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{
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ULONG FourByte = Link->RawDataSize / 4;
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ULONG TwoByte = (Link->RawDataSize - (FourByte * 4)) / 2;
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ULONG OneByte = (Link->RawDataSize - (FourByte * 4) - (TwoByte * 2));
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PNATIVE_CODE_BLOCK Block = new NATIVE_CODE_BLOCK;
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if (!Block)
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return NULL;
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if (SaveFlags && !ObfEmitPushfqInst(Block))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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ULONG Count = FourByte;
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while (Count)
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{
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INT32 RipDelta = Link->RawDataSize - ((FourByte - Count) * 4);
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if (SaveFlags)
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RipDelta += 1;
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RipDelta += (FourByte - (Count - 1)) * DWORD_XOR_INST_LENGTH;
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RipDelta *= (-1);
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RipDelta += DeltaToInst;
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if (!ObfEmitRipRelativeXorD(Block, RipDelta, XorData->Data[FourByte - Count]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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--Count;
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}
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if (TwoByte)
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{
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INT32 RipDelta = Link->RawDataSize - (FourByte * 4);
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if (SaveFlags)
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RipDelta += 1;
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RipDelta += (FourByte * DWORD_XOR_INST_LENGTH);
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RipDelta += WORD_XOR_INST_LENGTH;
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RipDelta *= (-1);
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RipDelta += DeltaToInst;
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if (!ObfEmitRipRelativeXorW(Block, RipDelta, XorData->Data[3]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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}
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if (OneByte)
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{
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INT32 RipDelta = Link->RawDataSize - (FourByte * 4) - (TwoByte * 2);
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if (SaveFlags)
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RipDelta += 1;
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RipDelta += (FourByte * DWORD_XOR_INST_LENGTH);
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RipDelta += WORD_XOR_INST_LENGTH;
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RipDelta += BYTE_XOR_INST_LENGTH;
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RipDelta *= (-1);
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RipDelta += DeltaToInst;
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if (!ObfEmitRipRelativeXorB(Block, RipDelta, XorData->Data[4]))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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}
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if (SaveFlags && !ObfEmitPopfqInst(Block))
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{
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NcDelete(Block);
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delete Block;
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return NULL;
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}
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return Block;
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}
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