Семантический анализ структуры EXE файла и дисассемблер (с примерами и исходниками), вирусология

Operand1[0] := Chr(CharPos-k);

Move(Line[k], Operand1[1], CharPos-k);

end;

'D': if Operand1 = 'DWORD' then begin

TypeOverride := D;

SkipBT; if Stop then goto EndParseLine;

SkipUBT;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand1 := Copy(Line, k, CharPos-k); *)

Operand1[0] := Chr(CharPos-k);

Move(Line[k], Operand1[1], CharPos-k);

end;

'F': if Operand1 = 'FAR' then begin

TypeOverride := F;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand1 := Copy(Line, k, CharPos-k); *)

Operand1[0] := Chr(CharPos-k);

Move(Line[k], Operand1[1], CharPos-k);

end;

end;

SkipBTC; if Stop then goto EndParseLine;

(* second operand *)

k := CharPos;

SkipUBTC;

(* Operand2 := Copy(Line, k, CharPos-k); *)

Operand2[0] := Chr(CharPos-k);

Move(Line[k], Operand2[1], CharPos-k);

(* check for type override operators *)

case Operand2[1] of

'B': if Operand2 = 'BYTE' then begin

TypeOverride := B;

SkipBT; if Stop then goto EndParseLine;

SkipUBT;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand2 := Copy(Line, k, CharPos-k); *)

Operand2[0] := Chr(CharPos-k);

Move(Line[k], Operand2[1], CharPos-k);

end;

'W': if Operand2 = 'WORD' then begin

TypeOverride := W;

SkipBT; if Stop then goto EndParseLine;

SkipUBT;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand2 := Copy(Line, k, CharPos-k); *)

Operand2[0] := Chr(CharPos-k);

Move(Line[k], Operand2[1], CharPos-k);

end;

'D': if Operand2 = 'DWORD' then begin

TypeOverride := D;

SkipBT; if Stop then goto EndParseLine;

SkipUBT;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand2 := Copy(Line, k, CharPos-k); *)

Operand2[0] := Chr(CharPos-k);

Move(Line[k], Operand2[1], CharPos-k);

end;

'F': if Operand2 = 'FAR' then begin

TypeOverride := F;

SkipBT; if Stop then goto EndParseLine;

k := CharPos;

SkipUBTC;

(* Operand2 := Copy(Line, k, CharPos-k); *)

Operand2[0] := Chr(CharPos-k);

Move(Line[k], Operand2[1], CharPos-k);

end

end

end;

EndParseLine: end;

procedure Pass1;

var

_Offset,

_Label, _Mem,

Status : INTEGER;

function OperandType(var Operand: STR12): ReferenceTypes;

begin

case Operand[2] of

'X': case Operand[1] of

'A': OperandType := W;

'B': OperandType := W;

'C': OperandType := W;

'D': OperandType := W

end;

'S': case Operand[1] of

'C': OperandType := W;

'D': OperandType := W;

'E': OperandType := W;

'S': OperandType := W

end;

'L': case Operand[1] of

'A': OperandType := B;

'B': OperandType := B;

'C': OperandType := B;

'D': OperandType := B

end;

'H': case Operand[1] of

'A': OperandType := B;

'B': OperandType := B;

'C': OperandType := B;

'D': OperandType := B

end;

'I': case Operand[1] of

'S': OperandType := W;

'D': OperandType := W

end;

'P': case Operand[1] of

'B': OperandType := W;

'S': OperandType := W

end

end (* case *)

end;

procedure MemoryOperand(var Operand, OperandX: STR12; Position: BYTE;

ExplicitType:

ReferenceTypes);

begin

if (Ord(Operand[0])=6) then begin

if (Operand[1] = '[') AND (Operand[6] = ']') then begin

Val ( '$'+Copy(Operand, 2, 4), _Mem, Status);

if Status = 0 then begin (* valid 4 digit hex number *)

case ExplicitType of

N: ExplicitType := W; (* indirect jump or call *)

F: ExplicitType := D (* far indirect jump or call *)

end;

if (ExplicitType <> None) then

StoreReference (_Offset, _Mem, ExplicitType, Position)

else

StoreReference (_Offset, _Mem, OperandType(OperandX), Position);

end (* valid memory operand *)

end (* [,] *)

end (* length = 6 *)

end;

begin (* Pass 1 *)

gotoXY(1,25); Write('Pass 1 , Line ');

LineCount := 0;

while NOT EOF(f_in) do begin

readln(f_in, Line);

LineCount := succ(LineCount);

if (LineCount and $000F) = 0 then begin

gotoXY(16,25);

write(LineCount:3)

end;

ParseLine(ParsedLine);

with ParsedLine do begin

(****

gotoxy(12,wherey);writeln(offset,'|','|',opcode,'|',

operand1,'|',operand2,'|');

****)

Val ( '$'+Offset, _Offset, Status);

if Status = 0 then begin

Status := -1;

(* check for opcodes with CODE_LABEL operands *)

case OpCode[1] of

'J': begin

Val ( '$'+Operand1, _Label, Status);

if Status <> 0 then begin

if (OpCode = 'JMP') AND (TypeOverride=None) then

TypeOverride := N; (* try indirect NEAR jump *)

end

end;

'C': if OpCode = 'CALL' then begin

Val ( '$'+Operand1, _Label, Status);

if (Status <> 0) AND (Operand1[5]=':') then begin

Val('$'+Copy(Operand1, 6, 4), _Label, Status);

if Status = 0 then StoreReference (_Offset, _Label, F,

1);

Status := -1;

end

end;

'L': if (OpCode = 'LOOP') OR

(OpCode = 'LOOPZ') OR (OpCode = 'LOOPNZ')

then Val ( '$'+Operand1, _Label, Status);

'P': if OpCode = 'PUSH' then TypeOverride := W

else if OpCode = 'POP' then TypeOverride := W;

end (* case *);

if Status = 0 then begin (* valid near label *)

StoreReference (_Offset, _Label, N, 1)

end;

MemoryOperand(Operand1, Operand2, 1, TypeOverride);

MemoryOperand(Operand2, Operand1, 2, TypeOverride);

end (* valid offset *)

end (* with ParsedLine *)

end (* while *);

gotoXY(16,25); write(LineCount:3);

end (* Pass 1 *);

procedure Pass2;

type

PrefixTypes = (NoPrefix, REP, REPZ, REPNZ, LOCK, CS, DS, ES, SS);

var

k, _Offset,

NextOffset,

NextRef,

Status : INTEGER;

Prefix : PrefixTypes;

ASMLine : STR80;

function TestPrefix: BOOLEAN;

var

HexByte, Status: INTEGER;

begin

case ParsedLine.OpCode[3] of (* test for prefix opcodes *)

':', 'P', 'C' : begin

Val('$'+ParsedLine.HexCode, HexByte, Status);

case HexByte of

$2E: begin Prefix := CS; TestPrefix := true end;

$26: begin Prefix := ES; TestPrefix := true end;

$3E: begin Prefix := DS; TestPrefix := true end;

$36: begin Prefix := SS; TestPrefix := true end;

$F2: begin Prefix := REPNZ; TestPrefix := true end;

$F3: begin Prefix := REPZ; TestPrefix := true end;

$F0: begin Prefix := LOCK; TestPrefix := true end;

else TestPrefix := false

end

end

else TestPrefix := false

end;

end;

begin (* Pass 2 *)

gotoXY(1,25); Write('Pass 2 , Line ');

NextOffset := 0;

NextRef := 0;

Prefix := NoPrefix;

LineCount := 0;

while NOT EOF(f_in) do begin

readln(f_in, Line);

LineCount := succ(LineCount);

if (LineCount and $000F) = 0 then begin

gotoXY(16,25);

write(LineCount:3)

end;

ParseLine(ParsedLine);

if NOT TestPrefix then begin

with ParsedLine do begin

if (Prefix = REPZ) OR (Prefix = REPNZ) then begin

if (Opcode[1] IN ['M', 'L', 'S']) AND (Ord(OpCode[0])<>0) then

Prefix := REP

end;

Val ( '$'+Offset, _Offset, Status);

if Status = 0 then begin

if _Offset = SymbolTable[NextOffset].offset then begin

case SymbolTable[NextOffset].reftype of

N: begin

Move(Operand1[1], Operand1[3], 4);

Operand1[0] := succ(succ(Operand1[0]));

Operand1[1] := 'L';

Operand1[2] := '_';

end;

B,W,D: begin

if SymbolTable[NextOffset].position = 1 then begin

Operand1[1] := 'V';

Operand1[6] := '_';

end else begin

Operand2[1] := 'V';

Operand2[6] := '_';

end

end;

end;

NextOffset := succ(NextOffset);

end;

while AuxTable[NextRef].reference < _Offset do

NextRef := succ(NextRef);

while _Offset = AuxTable[NextRef].reference do begin

case AuxTable[NextRef].reftype of

N: begin

Writeln(f_out, ' L_'+ Offset+':');

end;

B: begin

Writeln(f_out, ' V_'+ Offset+tab+'DB', tab, '?');

end;

W: begin

Writeln(f_out, ' V_'+ Offset+tab+'DW', tab, '?');

end;

D: begin

Writeln(f_out, ' V_'+ Offset+tab+'DD', tab, '?');

end;

end;

repeat NextRef:=succ(NextRef)

until (AuxTable[NextRef].reftype <> AuxTable[NextRef-1].reftype)

OR

(_Offset <> AuxTable[NextRef].reference) OR

(NextRef >= Symbol_Table_Length);

end;

if Offset[0] <> Chr(0) then begin

write(f_out, tab, tab);

case Prefix of

REP: begin

write(f_out, 'REP ');

Prefix := NoPrefix

end;

REPZ: begin

write(f_out, 'REPZ ');

Prefix := NoPrefix

end;

REPNZ:begin

write(f_out, 'REPNZ ');

Prefix := NoPrefix

end;

LOCK: begin

write(f_out, 'LOCK ');

Prefix := NoPrefix

end;

end;

write(f_out, OpCode, tab);

if Ord(Operand1[0]) > 2 then begin

case TypeOverride of

None: ;

B : write(f_out, 'BYTE PTR ');

W : write(f_out, 'WORD PTR ');

D : write(f_out, 'DWORD PTR ');

F : write(f_out, 'FAR PTR ');

end;

case Prefix of

NoPrefix: ;

CS: begin write(f_out, 'CS:'); Prefix := NoPrefix end;

ES: begin write(f_out, 'ES:'); Prefix := NoPrefix end;

SS: begin write(f_out, 'SS:'); Prefix := NoPrefix end;

DS: begin write(f_out, 'DS:'); Prefix := NoPrefix end;

end;

end;

write(f_out, Operand1);

if Operand2[0]<>Chr(0) then begin

write(f_out, ', ');

if Ord(Operand2[0]) > 2 then begin

case TypeOverride of

None: ;

B : write(f_out, 'BYTE PTR ');

W : write(f_out, 'WORD PTR ');

D : write(f_out, 'DWORD PTR ');

F : write(f_out, 'FAR PTR ');

end;

case Prefix of

NoPrefix: ;

CS: begin write(f_out, 'CS:'); Prefix := NoPrefix end;

ES: begin write(f_out, 'ES:'); Prefix := NoPrefix end;

SS: begin write(f_out, 'SS:'); Prefix := NoPrefix end;

DS: begin write(f_out, 'DS:'); Prefix := NoPrefix end;

end;

end;

write(f_out, Operand2);

end

else write(f_out, tab);

end;

if Comment N then begin

HexString(RefStr, AuxTable[CharPos].offset);

if k = 5 then begin

k:=0;

writeln(f_out);

write(f_out, tab,tab,tab,tab, '; R_', RefStr)

end

else write(f_out, ' ,R_', RefStr);

k := succ(k)

end;

CharPos:= succ(CharPos)

end;

if reftype <> N then writeln(f_out);

end;

end;

writeln(f_out);

end;

begin

rep[none]:='NONE';

rep[B]:='BYTE';rep[W]:='WORD';rep[D]:='DWORD';

rep[N]:='NEAR';rep[F]:='FAR';

Current_SymbolTable_Index:= 0;

write('Enter filename: '); readln(FileName);

FileExt := false;

for CharPos:=1 to Length(FileName) do FileExt := FileName[CharPos] = '.';

if FileExt then assign(f_in, FileName)

else assign(f_in, FileName+'.DEB');

(* start pass 1 *)

reset(f_in);

Pass1;

Symbol_Table_Length := Current_SymbolTable_Index;

Current_SymbolTable_Index := 0;

Writeln;

Writeln(Symbol_Table_Length, ' symbols');

(* Sort symboltable *)

SortInputIndex := 0;

SortOutputIndex := 0;

Writeln('Sorting symboltable ...');

SortStatus := TurboSort(SizeOf(TableEntry));

if SortStatus <> 0 then writeln('Error ', SortStatus:2, ' during

sorting');

if FileExt then begin

CharPos:= 1;

while FileName[CharPos] <> '.' do CharPos:= succ(CharPos);

FileName := copy(FileName, 1, pred(CharPos));

end;

assign(f_out, FileName+'.DBO');

rewrite(f_out);

Writeln('Writing cross-reference');

CrossRefList;

(* start pass 2 *)

reset(f_in);

Pass2;

close(f_out);

close(f_in)

end.

-------------------- end --------------

Литература.

Питер Абель «АССЕМБЛЕР И ПРОГРАММИРОВАНИЕ ДЛЯ IBM PC».

Технологический институт Британская Колумбия.

2. В.И.Юров «Assembler (практикум и пособие)». Изд. Питер.

Москва.2002.

3. А.А. Абдукодиров «IBM PC АССЕМБЛЕРИДА ПРОГРАММАЛАШ

АСОСЛАРИ» Университет 1998.

4. Р.Браун. «Справочник по прерываниям IBM PC» Москва,

издательство "Мир", 1994.

5. Р.Джордейн «Справочник программиста персональных компьютеров

типа IBM PC, XT и AT». Москва, "Фин. и статистика" 1992.

6. И.В.Юров «Справочная система по языку ассемблера IBM PC». СПВУРЭ

ПВО. 2000.

7. Интернет сайты:

www.ilf.net

home1.gte.net/rdhaar/hotbox/

www.agate.net/~krees/

www.cdc.net/~x/

www.chibacity.com/chiba/

www.conexis.es/~amasso/

www.virewall.narod.ru/vir.html

www.etu.net.ru

www.ruler.h1.ru/asm/abel/

www.google.com/search/asm

www.hangup.da.ru/

www.home.pages.at/rolik/

www.bib.ru

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