Footprinting (also known as reconnaissance) is the technique used for gathering information about computer systems and the entities they belong to. To get this information, a hacker might use various tools and technologies. This information is very useful to a hacker who is trying to crack a whole system.

What is the main objective of footprinting reconnaissance?

The objectives of footprinting are to: Learn security posture Analyze the security posture of the target, find loopholes, and create an attack plan. Identify focus area Using different tools and techniques, narrow down the range of IP addresses

What is reconnaissance activity?

Active reconnaissance is a type of computer attack in which an intruder engages with the targeted system to gather information about vulnerabilities. … This type of recon requires that attacker interact with the target.

Types of Footprinting

There are two types of footprinting:

  • Passive footprinting
  • Active footprinting

Passive footprinting means collecting information without interacting with the target directly. This type of footprinting is used when information gathering must not be detected by the target.

Active footprinting means collecting information by interacting with the target directly. With this type of footprinting there is a chance that the target becomes aware of the information gathering.

Attackers use footprinting to collect the following information:

  • Network information
    • Domains
    • Subdomains
    • IP addresses
    • Whois and DNS records
  • System information
    • Web server operating systems
    • Server locations
    • Users
    • Passwords
  • Organization information
    • Employee information
    • Organization’s background
    • Phone numbers
    • Locations

Objectives of Footprinting

The objectives of footprinting are to:

  • Learn security posture Analyze the security posture of the target, find loopholes, and create an attack plan.
  • Identify focus area Using different tools and techniques, narrow down the range of IP addresses.
  • Find vulnerabilities Use the collected information to identify weaknesses in the target’s security.
  • Map the network Graphically represent the target’s network and use it as a guide during the attack.

How and Where to Collect Information

There are plenty of tools and online resources that we can use to collect information about our target.

Search Engine and Online Resources

Search engines can be used to extract information about the target organization. Search results can include information about the target organization’s employees, intranet, login pages, and other information that could be useful to attackers.

One way of gathering information using search engines is by utilizing google hacking techniques.

Google hacking is a technique which attackers use to perform a complex search and extract important information about their targets. It involves using a set of search operators and building complex queries. The operators that are used in Google hacking are called dorks.

Whois, IP Geolocation, and DNS Interrogation


Whois refers to a query and response protocol which is used for retrieving information about assigned Internet resources.

Whois databases contain domain owners’ personal information and are maintained by the Regional Internet Registries.

There are two type of data models that exist:

  • Thick whois
  • Thin whois

Thick whois contains all information from all registrars for the specified set of data. Thin whois contains limited information about the specified set of data.

Whois query results typically include:

  • Domain details
  • Domain owner details
  • Domain server
  • Net range
  • Domain expiration
  • Creation and last update dates

Regional Internet Registries, which maintain the whois databases, include:

  • ARIN (American Registry for Internet Numbers)
  • AFRINIC (African Network Information Center)
  • APNIC (Asia Pacific Network Information Center)
  • RIPE (Reseaux IP Europeens Network Coordination Centre)
  • LACNIC (Latin American and Caribbean Network Information Center)

IP Geolocation

IP geolocation helps find location information about a target such as country, city, postal code, ISP, and so on. With this information, hackers are able to perform social engineering attacks on the target.

DNS Interrogation

DNS footprinting refers to collecting information about DNS zone data, which includes information about key hosts in the network.

DNS interrogation tools help attackers to perform DNS footprinting. Using these tools, attackers are able to obtain information about server types and their locations.

Email Footprinting

Email footprinting refers to collecting information from emails by monitoring the email delivery and inspecting the headers.

Information collected through email footprinting includes:

  • IP address of the recipient
  • Geolocation of the recipient
  • Delivery information
  • Visited links
  • Browser and OS information
  • Reading time

Email headers contain information about the sender, subject, and recipient. All this information is valuable to hackers when planning to attack their target.

Information contained in email headers include:

  • Sender’s name
  • IP/Email address of the sender
  • Mail server
  • Mail server authentication system
  • Send and delivery stamp
  • Unique number of the message

It is also possible to track emails using various tracking tools. Email tracking tools have the capability of tracking emails and inspecting their headers to extract useful information. The sender is notified of the email being delivered and opened by the recipient.

Website Footprinting

Website footprinting is a technique in which information about the target is collected by monitoring the target’s website. Hackers can map the entire website of the target without being noticed.

Website footprinting gives information about:

  • Software
  • Operating system
  • Subdirectories
  • Contact information
  • Scripting platform
  • Query details

By examining the website headers, it is possible to obtain information about the following headers:

  • Content-Type
  • Accept-Ranges
  • Connection Status
  • Last-Modified Information
  • X-powered-by Information
  • Web Server Information

Additional ways to gather information is through HTML Source Code and cookie examination. By examining the HTML source code, it is possible to extract information from the comments in the code, as well as gain insight into the file system structure by observing the links and image tags.

Cookies too can reveal important information about the software that is running on the server and its behavior. Also, by inspecting sessions, it is possible to identify the scripting platforms.

There are programs designed to help in website footprinting. These programs are called web spiders and they methodically browse a website in search of specific information. Information collected this way can help attackers perform social engineering attacks.

Cloning Websites

Website mirroring or website cloning refers to the process of duplicating a website. Mirroring a website helps in browsing the site offline, searching the website for vulnerabilities, and discovering valuable information.

Websites may store documents of different format which in turn may contain hidden information and metadata that can be analyzed and used in performing an attack. This metadata can be extracted using various metadata extraction tools as well as help attackers perform social engineering attacks.

Network Footprinting

Network footprinting refers to the process of collecting information about the target’s network. During this process, attackers collect network range information and use the information to map the target’s network.

Network range gives attackers an insight into how the network is structured and which machines belong to the network.


Nmap is a tool used for network discovery. It uses raw IP packets to determine the available hosts on the network, the services offered by those hosts, operating systems they are running, firewall types that are being used, and other important characteristics.

Nmap features include the ability to scan large networks as well as mapping out networks.


Traceroute programs are used for discovering routers that are on the path to the target host. This information helps with carrying out man-in-the-middle and other related attacks.

Traceroute uses ICMP protocol and the TTL field in the IP header to discover the route. It records IP addresses and DNS names of discovered routers.

The results of a traceroute help attackers collect information about network topology, trusted routers, as well as firewall locations. They can use this to create network diagrams and plan their attacks.


Active Reconnaissance

Active reconnaissance is a type of computer attack in which an intruder engages with the targeted system to gather information about vulnerabilities. This may be through automated scanning or manual testing using various tools like ping, traceroute, netcat etc. This type of recon requires that attacker interact with the target. This recon is faster and more accurate, however it also makes much more noise. Since the attacker have to interact with the target to gain information, there’s an increased chance that the recon will get caught by a firewall or one of the network security devices. (Intrusion Detection Systems, network firewalls, etc.)

Tools and Techniques Used

In order to gather information from the target host, attacker normally use port scanning techniques.

Nmap is probably the most well-known tool for active network reconnaissance. Nmap is a network scanner designed to determine details about a system and the programs running on it. This is accomplished through the use of a suite of different scan types that take advantage of the details of how a system or service operates. By launching scans against a system or a range of IP addresses under a target’s control, a hacker can learn a significant amount of information about the target network.

Metasploit is primarily designed as an exploitation toolkit. It contains a variety of different modules that have prepackaged exploits for a number of vulnerabilities. With Metasploit, even a novice hacker has the potential to break into a wide range of vulnerable machines.

Although it was designed as an exploit toolkit, Metasploit can also be effectively used for reconnaissance. At the minimum, using the autopwn option on Metasploit allows a hacker to try to exploit a target using any means necessary. More targeted analysis can allow a hacker to perform reconnaissance using Metasploit with more subtlety.

Port Scanning

Port Scanning is a systematically scanning computer ports as whole information is going in and out is through portand port scanning identifies open ports to a computer.Through port scanning attacker infer which services are visible and where attack is possible. Basic principal of port scanning is that to retrieve data from the opened port and analyze it.

Passive Reconnaissance

Passive reconnaissance is an attempt to gain information about targeted computers and networks without actively engaging with the systems. It is a gathering the information without alerting victim. If the victim host alerted then it drastically increases security against the attack.

Tools and Techniques Used

Wireshark is best known as a network traffic analysis tool, but it can also be invaluable for passive network reconnaissance. If an attacker can gain access to an organization’s Wi-Fi network or otherwise eavesdrop on the network traffic of an employee (e.g., by eavesdropping on traffic in a coffee shop), analyzing it in Wireshark can provide a great deal of useful intelligence about the target network.

Shodan is a search engine for internet-connected devices. As the Internet of Things grows, individuals and organizations increasingly are connecting insecure devices to the internet.

Using Shodan, a hacker may be able to find devices within the IP address range belonging to a company, indicating that they have the device deployed on their network. Since many IoT devices are vulnerable by default, identifying one or more on the network may give a hacker a good starting point for a future attack.

OS Fingerprinting

OS Fingerprinting is a method for determining which operating system does the remote computer runs.OS Fingerprinting is mostly used for cyber reconnaissance as most exploitable vulnerabilities are operating system specific.

How to prevent Footprinting?

Footprinting Penetration Testing

Penetration testing refers to the process of testing the organization’s security posture using similar techniques and tools as that of an attacker, but with the knowledge and approval of the organization. Footprinting is the first step to perform in pen testing process. The pen tester will discover potential security liabilities that an attacker may exploit.

So, what is footprinting penetration testing ?

It helps in determining an organization’s information on the Internet such as network architecture, operating systems, applications, and users. The pen tester tries to gather publicly available sensitive information of the target by pretending to be an attacker. The target may be a specific host or a network.

Footprinting penetration testing helps organizations/businesses to:

  1. Prevent information leakage
  2. Reduce the chances of Social Engineering
  3. Prevent DNS record retrieval from public servers

Footprinting Countermeasures

Some of the footprinting countermeasures include:

  • Restricting access to social media
  • Enforcing security policies
  • Educating employees about security threats
  • Encrypting sensitive information
  • Disabling protocols that are not required
  • Proper service configuration

Footprinting Reports

Footprinting reports should include details about the performed tests, used techniques, and test results. It should also include a list of vulnerabilities and how they can be fixed. These reports should be kept highly confidential, so that they do not fall into wrong hands.


  • Perform continuous inspection of network traffic flows to detect and prevent port scans and host sweeps.
  • Implement security awareness training so users are mindful about what should and should not be posted – sensitive documents, customer lists, event attendees, job roles and responsibilities (i.e., using specific security tools within an organization), etc.

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Author: refuge_2020