[CentOS] an actual hacked machine, in a preserved state

Pete Travis lists at petetravis.com
Tue Jan 3 20:31:34 UTC 2012

On Jan 3, 2012 12:36 PM, "Ljubomir Ljubojevic" <office at plnet.rs> wrote:
> On 01/03/2012 04:47 PM, m.roth at 5-cent.us wrote:
> > Having been on vacation, I'm coming in very late in this....
> >
> > Les Mikesell wrote:
> >> On Tue, Jan 3, 2012 at 4:28 AM, Bennett Haselton<bennett at peacefire.org>
> >> wrote:
> > <snip>
> >>> OK but those are *users* who have their own passwords that they have
> >>> chosen, presumably.  User-chosen passwords cannot be assumed to be
> >>> secure against a brute-force attack.  What I'm saying is that if
> >>> the only user, by my reasoning you don't need fail2ban if you just
use a
> >>> 12-character truly random password.
> >>
> >> But you aren't exactly an authority when you are still guessing about
> >> the cause of your problem, are you?  (And haven't mentioned what your
> >> logs said about failed attempts leading up to the break in...).
> >
> > Further, that's a ridiculous assumption. Without fail2ban, or something
> > like it, they'll keep trying. You, instead, Bennett, are presumably
> > generating that "truly random" password[1] and assigning it to all your
> > users[2], and not allowing them to change their passwords, and you will
> > changing it occasionally and informing them of the change.[3]
> >
> > Right?
> >
> >          mark
> >
> > 1. How will you generate "truly random"? Clicks on a Geiger counter?
> > is no such thing as a random number generator.
> > 2. Which, being "truly random", they will write down somewhere, or store
> > it on a key, labelling the file "mypassword" or some such.
> > 3. How will you notify them of their new password - in plain text?
> Bennet was/is the only one using those systems, and only as root. No
> additional users existed prior to breach. And he is very persisting in
> placing his own opinion/belief above those he asks for help. That is why
> we have such a long long long thread. It came to the point where I am
> starting to believe him being a troll. Not sure yet, but it is getting
> there.
> I am writing this for your sake, not his. I decided to just watch from
> no on. This thread WAS very informative, I did lear A LOT, but enough is
> enough, and I spent far to much time reading this thread.
> --
> Ljubomir Ljubojevic
> (Love is in the Air)
> PL Computers
> Serbia, Europe
> Google is the Mother, Google is the Father, and traceroute is your
> trusty Spiderman...
> StarOS, Mikrotik and CentOS/RHEL/Linux consultant
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> http://lists.centos.org/mailman/listinfo/centos

I'm subscribed to this list just because of threads like this.  I want to
thank you all for exposing me to knowledge and discussion that reveals far
more than manpages or readmes - it helps a lot to know where to start
reading, and about what.

I am not a statistician,  but I feel an observation should be made on the
idea of an 'unguessable password.'  A 12 character string may have 12^42
possible permutations, but you are assuming that the correct guess will be
the last possible guess.  Simplistic probability puts the odds of success
at 50% - either the attacker gets it right, or they don't.   An intelligent
brute forcing tool could be making some assumptions about the minimum
length and complexity of your password, and ruling out the dictionary words
and strings based on them happens quickly.  The next guess has the same
rough odds of being correct as the 100563674th guess.

Of course, no amount of guessing will succeed on a system that doesn't
accept passwords.   System security, in terms of probability, seems to be
an 'every little bit helps' sort of endeavour.

Thanks again for the insights,


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