You can reset your dreambox password using dreambox remote:
1.install tuxbox commander using addons button
2. Start tuxboxcomander
3.go to in /var/etc/ and open the file passwd
4.press 4 on remote to go into edit mode.
The first line is root:*****:0:0:root:/home/root:/bin/sh
where the ****** delete it (by using remote arrows to move cursor right and then pressing volume minus)
delete *** until upto :0:0:root
and press ok and exit -> save
the first line should look like this after the edit
then login with user root and password leave empty
you could telnet and change the empty password with your own so known can easily hack into your dm box.