Interesting. Looks like keys are a risk. But, I still don't
understand, and I don't think the article was clear about, how a brute force
SSH password attack is possible over my very limited network. AT&T's
cheapest plan isn't a very big pipe and I use good passwords. The
attacker would have to have a great deal of luck.
Since I use ssh for personal access, I'm considering looking into a
firewall rule that simply walls out any IP that tries to log in with a
user that isn't my account. Another thing that makes me wonder about
this vector is the successful login wasn't from an account on my system.
It seems to me that the keys/certifcates are being attacked directly.
I've read other articles indicating that there are attackers in the wild doing this.
So, it seems to me that eliminating key/certificate logins from outward
facing systems may buy a lot of extra security. There were keys in my
.ssh directory, but whether I installed them or the attacker did, is not
clear. I wouldn't need them, but it is possible I could have created
them at some point over the last 15 years I've been using this system :)
-Gary
On Fri, Aug 05, 2022 at 03:54:33AM -0600, Linus Sphinx wrote:
> Join the club.
> https://www.bleepingcomputer.com/news/security/new-linux-malware-brute-forc…
>
> On Tue, Aug 2, 2022 at 12:43 PM Gary <saclug(a)garymcglinn.com> wrote:
>
> > Hi Brian,
> >
> > Open letter.
> >
> > I remember years ago you did a presentation on snort.
> >
> > Do you still like it?
> >
> > -Gary
> >
> > _______________________________________________
> > Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> > To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
> >
Before I powered down, while looking through the system logs on my poor
hacked computer, I noticed it was running chronyd, because it
complained. It is an old Fedora 13 system. It runs ntpd. That's bad.
But, on the VM and different box I am on on now, running Fedora 33, I
get:
[gary@entertain Mail]$ man -k date
date: nothing appropriate.
[gary@entertain Mail]$ man date
[gary@entertain Mail]$ man man
Where man date returns a man page. And according to the man page for
man:
man -k printf
Search the short descriptions and manual page names for the keyword
printf as regular expression. Print out any matches. Equivalent
to apropos printf.
Obviously man -k doesn't work.
I've been noticing more and more cruft like this. All kinds of things,
especially at the command line, where you can see, are broken.
I'm temporarily working from my entertainment system.
In reading so far, it looks like this is some kind of SSH key attack.
Makes me wonder why the default permissions in .ssh are what they are.
I must be missing somehting because the articles seem to call the .pub
file the private key. One even had a graphic with xxx.pub circled, to
show me where the private key is.
-Gary
Just when i was thinking of resurrecting meetings, Hacker Lab decided to
close! Wouldn't you know it! I wonder if Silver Skillet is still open?!
--
Brian Lavender
http://www.brie.com/brian/
"There are two ways of constructing a software design. One way is to
make it so simple that there are obviously no deficiencies. And the other
way is to make it so complicated that there are no obvious deficiencies."
Professor C. A. R. Hoare
The 1980 Turing award lecture
It looks like I've been hacked.
I came home after being away for 3 days to find my system had been rebooted. I have other systems that were fine, so I knew it wasn't a power glitch. My systems don't reboot if the power comes on. I checked my logs and the reboot occured at about 11 PM on Friday.
Before that, for at least hours and possibly days, there were a lot of login attempts. Some from users named terrorist, some that trace to Iran. I checked the audit log and found this:
type=CRYPTO_KEY_USER msg=audit(1659374984.916:5741): pid=5877 uid=0 auid=4294967295 ses=4294967295 msg='op=destroy kind=session fp=? direction=both spid=5878 suid=74 rport=51686 laddr=192.168.2.5 lport=23 exe="/usr/sbin/sshd" hostname=? addr=156.251.130.170 terminal=? res=success'
type=CRYPTO_KEY_USER msg=audit(1659374984.917:5742): pid=5877 uid=0 auid=4294967295 ses=4294967295 msg='op=destroy kind=server fp=b3:4d:28:a2:ce:77:2a:f8:58:21:75:95:d1:08:6d:26 direction=? spid=5877 suid=0 exe="/usr/sbin/sshd" hostname=? addr=156.251.130.170 terminal=? res=success
It traces to Africa. And I run sshd on port 23. This is the only IP I've found successful logins from. So, I've added a reject rule to the firewall.
It is interesting the journalctl only reports failed logins from this IP since the reboot. Audit.log has the successes, but no timestamp. I'm not sure why there should be continued failures from this address.
And now, I've got to start cleaning up.
And redoing with better security. Sigh.
-Gary
Permissions can be fun. I grant execute to the world to the operator home directory files, just for convenience.
But I haven't really played around with extended file attributes, for example. And I wonder if anyone actually uses SELinux.
And, I'm still trying to figure out how systemd is better than init.d. It's just different. I hate things that are just different since I waste energy learning them without gaining any benefit.
-Gary
----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
Date: Wed, 6 Jul 2022 15:36:00 -0600
From: Linus Sphinx <sphinxtar(a)gmail.com>
To: Gary <saclug(a)garymcglinn.com>
Subject: Re: [Lug-nuts] [sphinxtar(a)gmail.com: Re: [sphinxtar(a)gmail.com: Re:
Basic SSH]]
Downside is you always have that caveat of one user to rule them all, you
can hide him, tighten his permissions til he's almost useless but you still
have to have that one shared account for all the admins to use, after all
the goal is to have scripts that run root level stuff everywhere from one
location, sudo helps but for a large enterprise there is no avoiding the
descent into madness that is UNIX permissions itself.
On Wed, Jul 6, 2022 at 8:45 AM Gary <saclug(a)garymcglinn.com> wrote:
> Yes, I have a script to send a nice melody to my living room computer when
> my coffee is ready that uses at and ssh.
>
> But, I often log in and get up and do things and theoretically someone
> could walk in the front door and sit down. Not that I'm paranoid, but I
> don't like the session/user to be able to do too much or know too much. So
> I don't make accessing another box too easy, unless I have a good reason.
> Plus there is the whole layered defense concept and all that.
>
> So, for a lot of scripting with ssh certificates, I use user operator. It
> was just sitting around with it's teeth in its mouth, so I put it to work.
> Plus the name sounded sort of descriptive. I wrote a script to do
> clipboard sharing over the network, for example. And, since I don't log in
> as operator ever, unless I am adding scripts or features, I have less of a
> security concern.
>
> -Gary
>
> ----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
>
> Date: Wed, 6 Jul 2022 07:54:01 -0600
> From: Linus Sphinx <sphinxtar(a)gmail.com>
> To: Gary <saclug(a)garymcglinn.com>
> Subject: Re: [Lug-nuts] [sphinxtar(a)gmail.com: Re: Basic SSH]
>
> Way we had everything wired at etrade, made for some nice easy scripting.
>
> On Wed, Jul 6, 2022 at 6:37 AM Gary <saclug(a)garymcglinn.com> wrote:
>
> > I was thining of tyring that just to see if it would work. You would
> > think there would be an example of it somewhere. It's not how I'd like
> to
> > use it, but it would be a good way to figure things out.
> >
> > ----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
> >
> > Date: Wed, 6 Jul 2022 05:01:48 -0600
> > From: Linus Sphinx <sphinxtar(a)gmail.com>
> > To: Gary <saclug(a)garymcglinn.com>
> > Subject: Re: [Lug-nuts] Basic SSH
> >
> > Do you own both servers? Maybe generate keys and exchange them? Sorry for
> > the RTFM: https://man7.org/linux/man-pages/man1/ssh-keygen.1.html
> >
> >
> > On Tue, Jul 5, 2022 at 11:35 PM Gary <saclug(a)garymcglinn.com> wrote:
> >
> > > So, my eyes grow weary of google nonsense.
> > >
> > > But is there ever a way to use anything other than:
> > >
> > > ssh -L xxxx:localhost:yyyy server.com
> > > or
> > > ssh -L xxxx:server.com:yyyy server.com
> > >
> > > for example
> > >
> > > ssh -L xxxx:anotherserver.com:yyyy server.com
> > >
> > > for example when there are firewalls.
> > >
> > > How would it work? Certificates only? I'd like to use a password on
> > > anotherserver.com
> > >
> > > I know I could get what I want using a double login and chaining ports.
> > > But, it seems like a real waste if the :localhost: is just to tickle
> the
> > > bind addresses on the server.
> > >
> > > -Gary
> > >
> > > _______________________________________________
> > > Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> > > To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
> > >
> >
> > ----- End forwarded message -----
> > _______________________________________________
> > Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> > To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
> >
>
> ----- End forwarded message -----
> _______________________________________________
> Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
>
----- End forwarded message -----
Yes, I have a script to send a nice melody to my living room computer when my coffee is ready that uses at and ssh.
But, I often log in and get up and do things and theoretically someone could walk in the front door and sit down. Not that I'm paranoid, but I don't like the session/user to be able to do too much or know too much. So I don't make accessing another box too easy, unless I have a good reason. Plus there is the whole layered defense concept and all that.
So, for a lot of scripting with ssh certificates, I use user operator. It was just sitting around with it's teeth in its mouth, so I put it to work. Plus the name sounded sort of descriptive. I wrote a script to do clipboard sharing over the network, for example. And, since I don't log in as operator ever, unless I am adding scripts or features, I have less of a security concern.
-Gary
----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
Date: Wed, 6 Jul 2022 07:54:01 -0600
From: Linus Sphinx <sphinxtar(a)gmail.com>
To: Gary <saclug(a)garymcglinn.com>
Subject: Re: [Lug-nuts] [sphinxtar(a)gmail.com: Re: Basic SSH]
Way we had everything wired at etrade, made for some nice easy scripting.
On Wed, Jul 6, 2022 at 6:37 AM Gary <saclug(a)garymcglinn.com> wrote:
> I was thining of tyring that just to see if it would work. You would
> think there would be an example of it somewhere. It's not how I'd like to
> use it, but it would be a good way to figure things out.
>
> ----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
>
> Date: Wed, 6 Jul 2022 05:01:48 -0600
> From: Linus Sphinx <sphinxtar(a)gmail.com>
> To: Gary <saclug(a)garymcglinn.com>
> Subject: Re: [Lug-nuts] Basic SSH
>
> Do you own both servers? Maybe generate keys and exchange them? Sorry for
> the RTFM: https://man7.org/linux/man-pages/man1/ssh-keygen.1.html
>
>
> On Tue, Jul 5, 2022 at 11:35 PM Gary <saclug(a)garymcglinn.com> wrote:
>
> > So, my eyes grow weary of google nonsense.
> >
> > But is there ever a way to use anything other than:
> >
> > ssh -L xxxx:localhost:yyyy server.com
> > or
> > ssh -L xxxx:server.com:yyyy server.com
> >
> > for example
> >
> > ssh -L xxxx:anotherserver.com:yyyy server.com
> >
> > for example when there are firewalls.
> >
> > How would it work? Certificates only? I'd like to use a password on
> > anotherserver.com
> >
> > I know I could get what I want using a double login and chaining ports.
> > But, it seems like a real waste if the :localhost: is just to tickle the
> > bind addresses on the server.
> >
> > -Gary
> >
> > _______________________________________________
> > Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> > To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
> >
>
> ----- End forwarded message -----
> _______________________________________________
> Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
>
----- End forwarded message -----
I was thining of tyring that just to see if it would work. You would think there would be an example of it somewhere. It's not how I'd like to use it, but it would be a good way to figure things out.
----- Forwarded message from Linus Sphinx <sphinxtar(a)gmail.com> -----
Date: Wed, 6 Jul 2022 05:01:48 -0600
From: Linus Sphinx <sphinxtar(a)gmail.com>
To: Gary <saclug(a)garymcglinn.com>
Subject: Re: [Lug-nuts] Basic SSH
Do you own both servers? Maybe generate keys and exchange them? Sorry for
the RTFM: https://man7.org/linux/man-pages/man1/ssh-keygen.1.html
On Tue, Jul 5, 2022 at 11:35 PM Gary <saclug(a)garymcglinn.com> wrote:
> So, my eyes grow weary of google nonsense.
>
> But is there ever a way to use anything other than:
>
> ssh -L xxxx:localhost:yyyy server.com
> or
> ssh -L xxxx:server.com:yyyy server.com
>
> for example
>
> ssh -L xxxx:anotherserver.com:yyyy server.com
>
> for example when there are firewalls.
>
> How would it work? Certificates only? I'd like to use a password on
> anotherserver.com
>
> I know I could get what I want using a double login and chaining ports.
> But, it seems like a real waste if the :localhost: is just to tickle the
> bind addresses on the server.
>
> -Gary
>
> _______________________________________________
> Lug-nuts mailing list -- lug-nuts(a)bigbrie.com
> To unsubscribe send an email to lug-nuts-leave(a)bigbrie.com
>
----- End forwarded message -----
I'm Ron.
I live in Sacramento, near Bradshaw and Old Placerville. I am retired, at least for now. I hope I don't have to go back to work. When I was working I was a helpdesk worker for several companies and for the last 10 years I worked in one of the bigger Data Centers here in SAC.
I use Kubuntu by the way. : ^ )
Hobbies: Python and C programming, Running Emulators for OLD computers. Have had a working mainframe emulator working but don't right now.
