mirror of
https://github.com/vxunderground/MalwareSourceCode
synced 2024-06-16 12:08:36 +00:00
175 lines
4.4 KiB
PHP
175 lines
4.4 KiB
PHP
; Catchy32 v1.6-2 - Length Disassembler Engine 32bit
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; original source Catchy32.inc-orig (c) sars [HI-TECH] 2003
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; this slightly opimized version - herm1t'2004
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BITS 32
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CPU 386
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global catchy32
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pref66h equ 1
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pref67h equ 2
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catchy32: pushad
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mov esi, [esp + 36] ; pointer to opcode
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sub esp, 256 ; allocate space for the table in stack
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mov ebp, esp ; ebp <- opcode table
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mov edi, esp
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push esi
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;; (1) unpack table
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mov edx, esp ; save stack pointer
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push 115
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pop ecx
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call .data
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db 0x45,0x29,0x20,0x45,0x29,0x20,0x45,0x29
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db 0x20,0x45,0x29,0x20,0x45,0x29,0x36,0x45
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db 0x29,0x36,0x45,0x29,0x36,0x45,0x29,0x36
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db 0xe0,0xe0,0x60,0x25,0x57,0x30,0x28,0x40
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db 0xe7,0x27,0x2c,0x2b,0xc5,0xa0,0x31,0x40
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db 0x4f,0x40,0x29,0x60,0x87,0x8f,0x2b,0x2d
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db 0x25,0x2c,0x2e,0x2d,0x22,0x20,0x45,0x27
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db 0x20,0x85,0x87,0x2f,0x32,0x40,0x36,0x37
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db 0x20,0x25,0x60,0x65,0x33,0x40,0x35,0x34
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db 0x23,0x85,0x26,0x75,0x45,0x46,0x85,0x60
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db 0xb5,0xe5,0xe5,0xe5,0x65,0x4b,0x25,0x24
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db 0x85,0xef,0x2f,0xe5,0x25,0x20,0x21,0x2a
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db 0x25,0x20,0x21,0x2a,0xa5,0x35,0x2a,0x65
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db 0x2a,0x2b,0x2a,0x80,0x34,0xe5,0xe5,0x25
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db 0x34,0xc5,0x26
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; xlat table
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db 0x00,0x01,0x02,0x03,0x10,0x11,0x1e,0x22
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db 0x23,0x28,0x31,0x33,0x39,0x40,0x60,0x88
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db 0x89,0xc0,0xc2,0xe0,0xe1,0xee,0xf0,0xff
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.data: pop esi
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lea ebx, [esi + ecx]
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xor eax, eax
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.next: lodsb
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push ecx
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mov ecx, eax
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shr ecx, 5
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and al, 31
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xlat
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rep stosb
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pop ecx
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loop .next
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mov esp, edx ; restore stack frame
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;; /unpack
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pop esi
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push edi ; (2)
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mov edi, esi ; (3)
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cmp word [esi], 20cdh ; VXD call (6 bytes)
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jne ExtFlags
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inc esi
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inc esi
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lodsd
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CalcLen: sub esi, edi ; (3)
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cmp esi, 15
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jbe OK
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Error: xor esi, esi
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dec esi
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OK: pop esp ; (2)
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mov [esp+4*7], esi
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popad
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ret
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; ecx zero after loop
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;==============================================================================
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ExtFlags: xor eax, eax
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xor ebx, ebx
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cdq
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lodsb ;al <- opcode
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mov cl, al ;cl <- opcode
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cmp al, 0fh ;Test on prefix 0Fh
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jne NormTable
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lodsb
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inc ah ;EAX=al+100h (100h/2 - lenght first table)
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NormTable: shr eax, 1 ;Elements tables on 4 bits
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mov al, byte [ebp + eax]
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jc IFC1
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shr eax, 4 ;Get high 4-bits block if offset is odd, otherwise...
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IFC1: and al, 0fh
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xchg eax, ebx ;EAX will be needed for other purposes
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CheckFlags: cmp bl, 0Eh ;Test on ErrorFlag
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je Error
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cmp bl, 0Fh ;Test on PrefixFlag
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je Prefix
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or ebx, ebx ;One byte command
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jz CalcLen
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btr ebx, 0 ;Command with ModRM byte
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jc ModRM
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btr ebx, 1 ;Test on imm8,rel8 etc flag
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jc incr1
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btr ebx, 2 ;Test on ptr16 etc flag
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jc incr2
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and bl, 11110111b ;Reset 16/32 sign
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cmp cl, 0A0h ;Processing group 0A0h-0A3h
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jb Check66h
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cmp cl, 0A3h
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ja Check66h
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test ch, pref67h
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jnz incr2
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jmp incr4
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Check66h: test ch, pref66h
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jnz incr2
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incr4: inc esi
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inc esi
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incr2: inc esi
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incr1: inc esi
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jmp_CheckFlags: jmp CheckFlags
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;-----------------------------------------------
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Prefix: cmp cl, 66h
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je SetF66h
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cmp cl, 67h
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jne ExtFlags
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SetF67h: or ch, pref67h
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jmp ExtFlags
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;-----------------------------------------------
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SetF66h: or ch, pref66h
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jmp ExtFlags
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;-----------------------------------------------
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ModRM: lodsb
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cmp cl, 0F7h ;Check on 0F6h and 0F7h groups
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je F6F7
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cmp cl, 0F6h
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jne ModXX
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F6F7: test al, 00111000b ;Processing groups 0F6h and 0F7h
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jnz ModXX
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test cl, 00000001b
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jz incbt1
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test ch, 1
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jnz incbt2
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inc esi
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inc esi
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incbt2: inc esi
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incbt1: inc esi
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ModXX: mov edx, eax ;Processing MOD bits
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and al, 00000111b ;al <- only R/M bits
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test dl, 11000000b ;Check MOD bits
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jz Mod00
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jp CheckFlags ;Or c_Mod11
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js Mod10
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Mod01: test ch, pref67h
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jnz incr1 ;16-bit addressing
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cmp al, 4 ;Check SIB
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je incr2
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jmp incr1
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;-----------------------------------------------
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Mod00: test ch, pref67h
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jz Mod00_32 ;32-bit addressing
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cmp al, 6
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je incr2
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jmp jmp_CheckFlags
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;-----------------------------------------------
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Mod00_32: cmp al, 4 ;Check SIB
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jne disp32
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lodsb ;Processing SIB byte
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and al, 00000111b
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disp32: cmp al, 5
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je incr4
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jmp jmp_CheckFlags
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;-----------------------------------------------
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Mod10: test ch, pref67h
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jnz incr2 ;16-bit addressing
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cmp al, 4 ;Check SIB
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jne incr4
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inc esi
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jmp incr4
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