¥ 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 you.
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
¥ 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 else.
¥ 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 company.
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.