Aldo Foot wrote:
2008/1/22 Mikkel L. Ellertson <mikkel@xxxxxxxxxxxxxxxx>:
Aldo Foot wrote:
Well, the scenario I described actually happened years ago to someone I
knew.
If I create keys without a passphrase, and share the public keys between
two systems (A and B), then from system A I can log to system B by
simply saying "ssh user@B". This is very convenient for cron jobs.
This is particularly risky when the systems are accessed by the general
public.
How does someone finds out the username? I don't know... company
phonebook,
online profiles listing first/lastname, etc.
You do know that you first have to get the private key of the key
pair, right? So you have to crack user@A's account, at least to the
point of getting the private key. Remember, the key will not work
unless it is only readable by the user. The .ssh directory also
needs to be set this way. So just being able to log into machine A
is not enough. You also need access to the private key.
You are correct. My worst nightmare does not include stealing the private
key. But simply cracking into a user's account who has access to several
systems containing the keys.
Worst scenario is when someone brakes into a system gains root access
and does "su - user" to such account and by looking into the .shosts tries
his luck to other systems.
But even having a pass phrase does not help if someone uses dumb
passwords. Things like first name as user name, and last name as
password. Then they use their full name as the pass phrase on the
key. Or is machine B lets you ssh in using username/password, and
you have a user like this. The key is to use the tools responsibly.
Bingo! There lies my problem.
Perhaps a good practice is to configure accounts such as those for
cron jobs to use only specific commands.
Does anyone reading this thread uses such setup?
I'll play with this a bit.
Mikkel
--
I have some first hand experience with simple passwords. I chose my
password for my regular account to be very simple. After all no-one can
use it. WRONG! Someone did ssh to my system and correctly guessed the
simple password and never learned the root password but they did some
childish things.
That lesson cost nothing and it caused me to use a google type of
password. Longer than 6 characters with at least one number. I have seen
what could have been another ssh to me and a few tries at the password
and gone.
Karl
--
Karl F. Larsen, AKA K5DI
Linux User
#450462 http://counter.li.org.
PGP 4208 4D6E 595F 22B9 FF1C ECB6 4A3C 2C54 FE23 53A7
