Web Hosting Talk : Web Hosting Main Forums : Dedicated Server : Strange Reading

[Calibur747]

Hey all,

I have a strange reading showing up on the netstat readout for my linux box. It shows one of our nameservers connected to ede.nl.eu.undernet.org:ircd in a Close_Wait status.

Anyone know why this would be, and what ( if anything ) I should do about it?

It has only showed up recently, and so I am kind of puzzled.

Thanks.

[Xorlev]

Do you allow shell access to others? Remote connections through PHP/Perl? If not, then try to find which process it's coming from, and run some rootkit detection programs. I'd recommend running them anyways.

[Calibur747]

I don't allow shell access and I don't think I have ever set anything for or against remote connections with PHP or Perl. Where can I look to see if there are remote connections allowed?

[Xorlev]

If you can do a netstat -np you could possibly see the program using it.

[Calibur747]

My original netstat:

root@enterprise [~]# netstat
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 1064 0 ns1.*.com:36014 ede.nl.eu.undernet.org:ircd CLOSE_WAIT

My netstat -np readout:

root@enterprise [~]# netstat -np
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 1064 0 XXX.XXX.XX.XXX:36014 193.109.122.67:6667 CLOSE_WAIT 1491/[kjournald]
tcp 187 0 XXX.XXX.XX.XXX:59671 193.109.122.67:6667 CLOSE_WAIT 1491/[kjournald]

Anyonoe know why "kjournald" would be having my system connect with undernet ircd?

[Xorlev]

There's a possiblility it's been compromised. Load up rkhunter and run it, and maybe a few others and see if it picks up anything.

[morcego]

kjournald with pid 1491. Well, not impossible, but not likely either.
Sure looks like some process masq'ing as kjournald.

Maybe a look at /proc/1491 can give you a few tips ? /proc/1491/fd might also contain
interesting information.

[Steven]

Looks like you have a psybnc or something like that running. Follow the suggestion about looking in /proc. If that is the case you need to look into securing your server more.

[Calibur747]

It seemed to be running multiple instances under the same PID . I simply killed it and it hasn't returned in the netstat readouts.

Thanks for your help guys Greatly appreciated.

[morcego]

You really should give the machine a reboot to see if it comes back, and also to make sure the _correct_ kjournald is running.

[apollo88]

maybe could be an: ircd or psybnc, something about the world of irc..
Look in your /var/tmp, and see if you have got something of strange..

[Calibur747]

How can I be sure the correct kjournald is running?

[Calibur747]

WHM shows one at the following:

PID 412 (kjournald)
PID 1441 (kjournald)
PID 1491 ([kjournald]) /usr/lib/sshdlib/[kjournald /usr/lib/sshdlib
[kjournald]

[morcego]

Originally Posted by Calibur747

WHM shows one at the following:

PID 412 (kjournald)
PID 1441 (kjournald)
PID 1491 ([kjournald]) /usr/lib/sshdlib/[kjournald /usr/lib/sshdlib
[kjournald]

First, stop using WHM for this kind of thing. It is almost useless.

And yes, your host is compromised.. 412 is the real kjournald process.
You will also notice (if you use "ps auxww") that the real kjournald not only had a low pid, but it also has 0 RSS and VSZ.

/usr/lib/sshdlib/ ? Good bet you have some trace of the backdoor there, but not 100% sure. It can be anywhere.

So, in a nutshell, you are still compromised. And if the process has access to /usr/lib,
then you better rebuild your box from scratch, cause ... well, it is not your box anything. It is the hacker's.

[Calibur747]

Went to that directory and I found a bunch of files, including psybnc titled configs and scripts. I deleted this directory promptly.

Any other suggestions?