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TUCoPS :: Hacking Techniques :: footprnt.txt

Footprinting - How and why hackers gather information about systems

Footprinting: The Basics of Hacking

 What Is Footprinting?

Footprinting is the first and most convenient way that hackers use to gather
information about computer systems and the companies they belong to. The
purpose of footprinting to learn as much as you can about a system, it's remote
access capabilities, its ports and services, and the aspects of its security.

In order to perform a successful hack on a system, it is best to know as much as
you can, if not everything, about that system. While there is nary a company in the
world that isn't aware of hackers, most companies are now hiring hackers to protect
their systems. And since footprinting can be used to attack a system, it can also be
used to protect it. If you can find anything out about a system, the company that
owns that system, with the right personell, can find out anything they want about

In this talk, I will explain what the many functions of footprinting are and what they
do. I'll also footprint everyone's favorite website, just to see how much info we can
get on Grifter.

 Open Source Footprinting

Open Source Footprinting is the easiest and safest way to go about finding
information about a company. Information that is available to the public, such as
phone numbers, addresses, etc. Performing whois requests, searching through DNS
tables, and scanning certain IP addresses for open ports, are other forms of open
source footprinting. Most of this information is fairly easy to get, and getting it is
legal, legal is always good.

Most companies post a shit load of information about themselves on their website.
A lot of this information can be very useful to hackers and the companies don't even
realize it. It may also be helpful to skim through the webpage's HTML source to look
for comments. Comments in HTML code are the equivalent to the small captions
under the pictures in high school science books. Some comments found in the HTML
can hold small tid-bits of info about the company, otherwise not found anywhere

 Network Enumeration

Network Enumeration is the process of identifying domain names and associated
networks. The process is performing various queries on the many whois databases
found on the internet. The result is the hacker now having the information needed
to attack the system they are learning about. Companie's domain names are listed
with registrars, and the hacker would simply query the registrar to obtain the
information they are looking for. The hacker simply needs to know which registrar
the company is listed with. There are five types of queries which are as follows:

Registrar Query: This query gives information on potential domains matching the

Organizational Query: This is searching a specific registrar to obtain all instances of
the target's name. The results show many different domains associated with the

Domain Query: A domain query is based off of results found in an organizational
query. Using a domain query, you could find the company's address, domain name,
administrator and his/her phone number, and the system's domain servers. The
administrative contact could be very useful to a hacker as it provides a purpose for a
wardialer. This is also where social engineering comes into play. But that's a talk for
another time. Many administrators now post false phone numbers to protect
themselves from this.

Network Query: The fourth method one could use the American Registry for Internet
Numbers is to discover certain blocks owned by a company. It's good to use a broad
search here, as well as in the registrar query.

POC Query: This query finds the many IP adresses a machine may have.

 DNS Interrogation

After gathering the information needed using the above techniques, a hacker would
begin to query the DNS. A common problem with system adminstrators is allowing
untrusted, or worse, unknown users, to perform a DNS Zone Transfer. Many freeware
tools can be found on the internet and can be used to perform DNS interrogation.
Tools such as nslookup, for PC, and AGnet Tools, for Mac, are some common
programs used for this.

 Other Helpful Techniques Used In Footprinting

Ping Sweep: Ping a range of IP addresses to find out which machines are awake.

TCP Scans: Scan ports on machines to see which services are offered. TCP scans can
be performed by scanning a single port on a range of IPs, or by scanning a range of
ports on a single IP. Both techniques yeild helpful information.

UDP Scans: Send garbage UDP packets to a desired port. I normally don't perform
UDP scans a whole lot because most machines respond with an ICMP 'port
unreachable' message. Meaning that no service is available.

OS Indentification: This involves sending illegal ICMP or TCP packets to a machine.

The machine responds with unique invalid inputs and allows the hacker to find out
what the target machine is running.

 Let's Try It!

Ok, I've explained as best I can what the functions of footprinting are. Now we're
going to actually use them. Let's footprint to find out as much as we
can about Grifter. Keep in mind that I am using a mac and I don't know the
necessary tools to use on a PC when footprinting. For all the procedures listed
below, I will be using a utility known as AGnet Tools version 2.5.1. This application
allows you to use all of the basic funtions of footprinting in one easy to use
program. I know there are other security auditing tools for the mac out there which
offer more functions, but AGnet is the most user friendly program I can find.

Now, just by looking at the website, we know where the 2600 meetings are held and
at what time. This information really isn't useful right now because you obviously
managed to find your way here. Good for you. We find that Grifter also runs, and by going further into the website, we find that Grifter has
three main email contacts which are:

Ok, we have Grifter's three emails which we will use later. But for now, let's get
some information on We type in into the prompt of the
Name Lookup window in AGnet tools, and our result is this IP address:

But wait, just out of curiosity, what is the IP of We type the
domain into the Name Lookup prompt and we are given the same IP. We can safely
say that and are hosted on the same box. But if I
were to do a reverse name lookup on the IP, which domain will come up? or Neither, the result is Ah ha! So is the name of the box hosting and

So now that we have the IP, let's check to see if linuxninjas is awake. We type the
IP into the prompt in the Ping window. We'll set the interval between packets to 1
millisecond. We'll set the number of seconds to wait until a ping times out to 5.
We'll set the ping size to 500 bytes and we'll send ten pings.

Ten packets sent and ten packets received. returned a message to
my computer within an average of 0.35 seconds for every packet sent. Linuxninjas is
alive and kicking.

Moving on. Remember Grifter's three email addresses? What can we do with those?
This is where Finger comes in. A lot of businesses nowadays don't run finger,
because it reveals too much information about any one user on a system. But of
course, it never hurts to try. Let's enter Grifter's emails into the prompt in the Finger
window. = Finger failed. = Finger failed. = Finger failed.

Like I said, a lot of systems no longer use finger.

Ok, since Finger gave us bupkuss, let's move on to Whois. We open the Whois
window and type into the Query prompt, and into the Server prompt. This means we'll be asking
Network Solutions to tell us everything they know about

The result is this laundry list of info:

        Static Discharge (LINUXNINJAS-DOM) 511493
        SLC, UT 84151

        Domain Name: LINUXNINJAS.ORG

        Administrative Contact, Billing Contact:
        Wyler, Neil  (NWB43)
        Static Discharge 511493
        SLC, UT 84151

        Technical Contact:
        sutton, kenny  (KS16306)  root@HEKTIK.COM
        hektik 511493
        SLC, UT 84151

        Record last updated on 17-Aug-2001.
        Record expires on 11-Aug-2002.
        Record created on 11-Aug-2000.
        Database last updated on 12-Dec-2001 04:06:00 EST.

        Domain servers in listed order:


Wow. Check this out. But remember that a lot of sysadmins post false info into their
registrars database. So these phone numbers could be payphones, and these
addresses could be whore houses. But as far as we know, we now have Grifter's real
name, his address and his phone number. We also have the same for Kenny. We
can see when Grifter registered, when it expires, and when it was
last updated. And look! We have another one of Grifter's email addresses. Lets run
it through Finger just for kicks. = Finger failed. Oh well.

Well, now that we have a bit of personal info on Grifter, let's check back with

A corner stone of footprinting is Port Scanning. Let's port scan and
see what kind of services are running on that box. We type in the linuxninjas IP into
the Host prompt of the Port Scan window. We'll start searching from port number 1,
and we'll stop at the default Sub7 port, 27374. Our results are:

        21      TCP     ftp
        22      TCP     ssh     SSH 1.99-OpenSSH_2.30
        25      TCP     smtp
        53      TCP     domain
        80      TCP     www
        110     TCP     pop3
        111     TCP     sunrpc
        113     TCP     ident

Just by this we know that Grifter is running a website and email, (duh), using POP3,
(Post Office Protocal version 3), SUNRPC (SUN Remote Procedure Call), and ident.
This could lead to some fun trying to access his FTP, or telnetting to his SMTP and
sending your mom midget porn through his email address.


All of these functions are very basic. They are simpe and easy to use. And above all,
they are legal. As I said in the introduction, legal is always good. Whenever
footprinting a system, keep in mind that you could find something that you aren't
supposed to see. If this happens, contact the sysadmin and let them know of it.
You could get into serious trouble if you misuse the information you find. Also let
them know of any bugs or exploits you may find. Who knows? If you help them out
enough, you could land a job with them protecting their system. Nothing could be
greater than getting paid to do what you do best. But try not to let money be your
motivation. Hacking is all about learning.

There is definetely more to learn about Grifter and his little websites. Like why I
found him sneaking around my backyard last night. But I guess we'll have to delve
into that later.

Especially be careful when trying to access any open ports you may find. Brute
forcing an ftp or a web server can also land you in a pile. If anything you try to
access requires a password, you probably shouldn't be there. But like I said, if you
access something important and it didn't ask you for a password, let the sysadmin
know of it.

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