     .    
     .   -
   ,    -.

   

  (Trojan horse)   ,  ,  -
   -  . ,    -
        mkfs:

while true
do

echo ' ,  .  ? --.' > /dev/console
done

         ,  
    .     -
,      .      -
   .

      , 
 PATH  ,    ,  
 ,    PATH. (    ,   
   /etc/profile     PATH  root   -
    root.)        
 mkfs.      PATH  , 
,   ,    .   -
   mkfs    .

         ,   -
 ,   ,   . , 
    is  si.       
 si   ,      ,      -
,  ,      .

        ,   -
  PATH     (:)     
PATH,   (.)    (::)     PATH. 
         
    setuid (.  5   "  
"    ).     
:

- find / -perm -4000 -exec Is -Ih (} \ 2> /dev/null

-rwsr-xr-x 1 root root 54K Apr 5 16 17 /usr/bin/lppasswd

-rwsr-xr-x 1 root root 111K Feb 17 10 26 /usr/bin/crontab

-rwsr-xr-x 1 root root 7.OK Apr 13 08 26 /usr/bin/kpac_dhcp_helper

-rws--x--x 1 root root 18K Mar 23 12 05 /usr/bin/chfn

-rws--x--x 1 root root 6.8K Mar 23 12 05 /usr/bin/newgrp

-rwsr-xr-x 1 root root 39K Apr 15 12 26 /usr/bin/at

-rwsr-xr-x 1 root root 42K Mar 30 13 45 /usr/bin/gpasswd

-r-s--x--x 1 root root 91K Feb 15 10 04 /usr/bin/passwd

-rwsr-xr-x 1 root root 17K Feb 17 09 12 /usr/bin/rlogin

 11.  :                     401