🚀 go-pugleaf

On Mon, 27 May 2002 06:50:40 +0800, Graham Daniell wrote:
> I have a RH 6.2 Linux server (torvalds) which provides internet
> connection for my home network of several Win9x PC's and one RH72
> PC.
> 
> For some time I have been getting attacked by this IP number:
> 
> May 26 12:04:35 torvalds in.telnetd[915]: refused connect from
> 195.119.1.180
> May 26 12:19:35 torvalds in.telnetd[921]: refused connect from
> 195.119.1.180
> May 26 18:08:44 torvalds in.telnetd[1069]: refused connect from
> 195.119.1.180
> May 26 18:51:07 torvalds in.telnetd[1087]: refused connect from
> 195.119.1.180
> 
> Last night's message log showed this:
> 
> May 26 20:49:41 torvalds network: Bringing up route unknown
> succeeded
> May 26 20:49:41 torvalds network: Bringing up route eth0 succeeded
> May 26 20:49:49 torvalds network: Bringing up route unknown
> succeeded
> May 26 20:49:50 torvalds network: Bringing up route eth0 succeeded
> May 26 20:55:49 torvalds network: Bringing up route unknown
> succeeded
> May 26 20:55:49 torvalds network: Bringing up route eth0 succeeded
> May 26 20:56:00 torvalds network: Bringing up route unknown
> succeeded
> May 26 20:56:00 torvalds network: Bringing up route eth0 succeeded
> 
> It looks to me like someone managed to install a route between my
> internal network and an unknown address (probably 195.119.1.180?)
> 
> Should I be worried?  (I already am :-(  )
> 
> Should I not use my internal network till I reformat and relaod my
> RH62 server?

Telnet and ftp are insecure.

login id and password is passed as clear text and can
be snatched with a packet sniffer off both ends of the connection.


That ip resolves to open.proxy.austnet.org

When you decide your box has been cracked,
unplug your system from the internet, Your machine is a menace to
society and you until it's cleaned it up. 

Here is why you need a FORMAT and clean install when your box IS cracked.
   http://www.linuxdoc.org/LDP/LG/issue36/kuethe.html
4'th paragraph.

Think about that paragraph.
You cannot use ANY of your pc's utilities to see if your box is cracked
and find what addtional files are installed.

http://www.chkrootkit.org   has a program for checking for rootkit installs
on the cracked box. That will tell you about known root kits if you have one.
The cracker may not have installed a rootkit.


What you can do is have a dual boot system. You install a second copy of
your OS and label it Auditor. You never, EVER mount it from the internet OS.

Anytime you THINK you've been cracked, you can boot into Auditor, mount the
internet os partition and start checking the internet OS partitions for new
files and whatnot.


Any time you KNOW your're box is cracked, you should:
o       Pull the box off the network. You do not want the police taking
        you and your equipment to jail because a cracker used it
        to crack a bank or military site. If the cracker removes their
        backtracks to their box, you get to do the jail time.

o       Put the hardrive(s) into a standalone machine,
	mount the disk(s) readonly,
	save any data, user files, ...,

o       Save a full copy of the disk(s) for your forensic attempt,
	save the disk(s) for FBI forensics if it's a Big, BIG dollar loss.

o       Re-FORMAT disk drives and do a fresh install from known clean
        source to remove any possible back doors and/or password sniffers
        the cracker installed.

o       Restore your saved files, verify that the restored files
	do not have the suid bit set  "find / -perm +6000 -ls".

o       Have everyone on the box's network change passwords and
	tell them that the cracker may have been running a
	password sniffer so they will not use the passwords ever again.
	Any other boxes logged into from the cracked box should
	have their passwords changed.


Install a modern firewall. Example: iptables is better than ipchains.
If you have a spare linux computer, you can use it to port scan
your box with nmap from http://www.insecure.org/nmap/ 

Get all the vendor updates to your distro.

You might want to read Armoring Linux
	http://www.linuxdoc.org/HOWTO/Security-Quickstart-HOWTO/index.html
        http://www.enteract.com/~lspitz/linux.html
http://www.ibiblio.org/pub/Linux/docs/HOWTO/Security-Quickstart-Redhat-HOWTO
http://www.ibiblio.org/pub/Linux/docs/linux-doc-project/solrhe/Secur
ing-Optimizing-Linux-RH-Edition-v1.3.txt

	http://www.linuxsecurity.com/docs/colsfaq.html
        http://www.securityportal.com/lskb/articles/
        http://www.securityportal.com/lasg/
keep an eye on
        http://www.cert.org/advisories/


For cheap install cd's 
http://cart.cheapbytes.com/cgi-bin/cart 
top left under Products.
For people accross the pond,
        http://www.linuxemporium.co.uk
        http://www.linux123.co.uk/
and for down under fokes
        http://www.cetustech.com.au/


Never login as root unless you have to.
Always login from the console, no su, telnet, ssh,..
That way a keystroke logger in your user account cannot
catch your root login password.

You can audit your system if you are using the  rpm   package manager with
  rpm -Va | grep '..5' > /tmp/verify.log
Runs for a while; more than 5 minutes.

/tmp/verify.log  will contain changes which you have made using
configuration tools

Hope crackers do not put in a rootkit which makes the rpm check obsolete.
I think this has happened, though not sure. On one of my boxes
it cored after about 2 minutes, log looked like it ran but never completes
the audit.

rpm -Va | grep '..5' will give you a warm feeling about what changed.
That warm feeling might turn into the warm feeling you get when
you do not get to the bathroom in time.  :(

The cracker could install trojaned files some where else and modify
PATH to use them instead of the files you just checked.
You could look at the report and see 
	S.5....T c /root/.bash_profile
	S.5....T c /root/.bashrc
You see that and say, "Ok, I did change those. No problem."
BZZZZzzit. WRONG answer, Cracker changed your PATH and you are
running his code.

It also does not show additional files. I have created a site file in
/etc/profile.d which puts my site/bin into PATH. 

Cracker can add his own cracked.sh file to change/add to PATH and
create aliases to substitute a stock command for his code.