Thursday, April 18, 2024

Secrets To Recon (Reconnaissance) – A Bug Hunter’s Guide

Hello, readers! Welcome back to our CyberSecurity Academy. Today, we’ll be taking a deep dive into one of the most important stages of ethical hacking or bug hunting: reconnaissance. This is where you gather as much information as possible about a target before you even begin to exploit any vulnerabilities. It’s a stage that is often overlooked by beginners, but it can make or break your efforts in a penetration testing or bug hunting context. Let’s take a look at how you can build a rock-solid foundation for your hacking endeavors.

What is Reconnaissance?

Reconnaissance, also known as “recon,” is the first stage in the ethical hacking process. It involves gathering information about your target system before attempting to identify vulnerabilities or weaknesses. This can include details about the system’s IP addresses, domain details, network topology, and more. The more information you can gather at this stage, the better equipped you will be to identify potential attack vectors.

Why is Recon Important?

The information gathered during the reconnaissance phase can provide invaluable insights that can help you identify vulnerabilities more effectively. For instance, knowing the operating system of a target server can allow you to focus on OS-specific vulnerabilities. Similarly, understanding the network topology can help you identify poorly secured entry points.

Passive vs Active Reconnaissance

Reconnaissance can be split into two main categories: passive and active.

Passive recon involves gathering information without directly interacting with the target system. This could be as simple as doing a WHOIS lookup on a domain or using a service like Shodan to find information about exposed devices.

Active recon, on the other hand, involves directly interacting with the target system. This could involve port scanning, DNS querying, or even sending crafted packets to the system to understand how it responds.

Both types of recon are important, and understanding how to do both effectively can significantly improve your bug hunting abilities.

Irrespective of type of recon, always respect rate limits and remain in-scope!

Tools of the Trade

There are numerous tools available that can aid in the recon process. Here are a few of the most popular ones:

  1. Burp Suite: This is a web application security testing platform. It can be used for various tasks in the security testing process, including mapping and analyzing application contents, inspecting and manipulating traffic between the browser and the web application, and more.
  2. ffuf: This is a tool used to find directories and files on web servers. It works by brute-forcing server directories and files using a wordlist. It’s a very fast web fuzzer written in Go.
  3. Shodan: This is a search engine for internet-connected devices. It can provide valuable information about a target system, such as exposed ports and running services.
  4. WHOIS lookup: This can provide information about who owns a domain, when it was registered, and other useful details.
  5. Google Dorks: These are advanced Google search techniques that can reveal sensitive information that has been accidentally exposed online.
Recommended:  A Security Researcher Contacted Me - What should I do?

Important: when using automated tools, please always ensure that you are setting rate limits/delay/sleeps and remain within scope

Best Practices for Recon

Here are a few best practices to keep in mind when performing reconnaissance:

  1. Always stay within legal boundaries: It’s crucial to remember that any form of hacking, including recon, can be illegal if you don’t have explicit permission from the owner of the system you’re targeting. Always ensure you have the necessary permissions before beginning any recon activities.
  2. Document everything: Keeping detailed notes on what you discover during the recon phase can be invaluable later on when you’re trying to exploit vulnerabilities.
  3. Don’t rush it: Recon is a process that shouldn’t berushed. Take your time to thoroughly explore and understand the target system.
  4. Use multiple tools: Don’t rely solely on one tool or method. Using a combination of tools and techniques can provide a more complete picture of the target system.

Reconnaissance is a critical first step in any ethical hacking or bug hunting endeavor. By taking the time to gather as much information as possible, you can lay a solid groundwork for your subsequent steps.

Advanced Reconnaissance Techniques

Sometimes, the standard tools and techniques might not be enough. That’s when advanced reconnaissance techniques come into play. Here are a few you might find helpful:

  • Subdomain enumeration: Subdomains can often host different applications and services from the main domain, providing potential additional attack vectors. Subdomain enumeration is a technique that involves identifying all the subdomains associated with a target domain. Tools like Sublist3r or Amass can be particularly useful for this purpose. They work by combining various techniques including search engines crawling, certificate transparency logs, and more. The result is a comprehensive list of subdomains that you can then further examine for potential vulnerabilities.
  • Web application testing: Web applications are complex systems with many components, and they often contain vulnerabilities that can be exploited. Manually testing is always a great start. Tools like OWASP ZAP and Burp Suite are designed specifically for web application testing. They can identify a wide range of vulnerabilities, such as injection vulnerabilities, cross-site scripting (XSS), and misconfigurations. Additionally, these tools often include functionality for manipulating HTTP requests and responses, allowing you to interact with the web application in ways a typical user or browser might not.
  • Content discovery: Not all directories or files on a web server are meant to be public. Sometimes, sensitive directories or files can be unintentionally exposed, providing a potential wealth of information. Content discovery tools like DirBuster, gobuster, or ffuf are designed to identify these hidden resources. They work by brute-forcing directory and file names against the web server and monitoring the responses.
  • Social Engineering: While not a technical method, social engineering is an incredibly effective reconnaissance technique. It involves manipulating people into revealing confidential information. Techniques can range from simple phishing attempts to complex scenarios involving multiple individuals and steps. It’s a stark reminder that humans can often be the weakest link in cybersecurity. Tools like the Social-Engineer Toolkit (SET) can help automate and streamline some social engineering efforts.
  • Data Leakage: Companies often have public and semi-public data repositories that can inadvertently contain sensitive information. This could include GitHub repositories, public Amazon S3 buckets, and more. Manually searching through these repositories can be time-consuming, but tools like GitRob, truffleHog, or Bucket Finder can automate the process, making it easier to identify potential data leakage.
Recommended:  Analysis of BlackGuard – a new info stealer malware being sold in a Russian hacking forum

Remember, these techniques should be used ethically and with permission. Always respect privacy and legality when conducting reconnaissance.

Reconnaissance is the first step in ethical hacking and bug hunting, and it’s an essential skill to master. By understanding your target thoroughly, you can plan your approach more effectively and increase your chances of success.

What to hunt for in 2023?

  • Insecure Direct Object References (IDOR): This is a type of access control vulnerability that arises when an application uses the actual name or key of an object when generating web pages. An attacker can manipulate these references to access unauthorized data. For example, a URL like “” might allow an attacker to view other accounts just by changing the id parameter. Testing for IDOR vulnerabilities usually involves manual testing, trying to change parameters and observing the responses. However, tools like Burp Suite can help automate some aspects of this process, such as easily changing request parameters.
  • Injection vulnerabilities: These occur when an application sends untrusted data to an interpreter. Injection vulnerabilities can lead to data loss, corruption, or disclosure to unauthorized parties, denial of service, and full system compromise. SQL Injection, Command Injection, and Cross-site Scripting (XSS) are common types of injection vulnerabilities.
  • Broken Authentication: This happens when session management functions related to authentication are implemented incorrectly, allowing attackers to compromise passwords, keys, session tokens, or exploit other implementation flaws to assume the identities of other users.
  • Sensitive Data Exposure: Many web applications and APIs do not properly protect sensitive data, such as financial data, usernames and passwords, and health information. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft, or other crimes.
Recommended:  Fixing indirect vulnerabilities without breaking your dependency tree

That’s it for today’s lesson. Remember, the aim of learning these skills is to strengthen security, not to exploit it. Always use your knowledge responsibly and ethically. Stay in Scope, Stay within limits, Stay safe, and happy hunting!’

Suggest an edit to this article

Check out our new Discord Cyber Awareness Server. Stay informed with CVE Alerts, Cybersecurity News & More!

Cybersecurity Knowledge Base


Remember, CyberSecurity Starts With You!

  • Globally, 30,000 websites are hacked daily.
  • 64% of companies worldwide have experienced at least one form of a cyber attack.
  • There were 20M breached records in March 2021.
  • In 2020, ransomware cases grew by 150%.
  • Email is responsible for around 94% of all malware.
  • Every 39 seconds, there is a new attack somewhere on the web.
  • An average of around 24,000 malicious mobile apps are blocked daily on the internet.
ClosePlease login
Share the word, let's increase Cybersecurity Awareness as we know it
- Sponsored -

Sponsored Offer

Unleash the Power of the Cloud: Grab $200 Credit for 60 Days on DigitalOcean!

Digital ocean free 200

Discover more infosec

User Avatar
Steven Black (n0tst3)
Hello! I'm Steve, an independent security researcher, and analyst from Scotland, UK. I've had an avid interest in Computers, Technology and Security since my early teens. 20 years on, and, it's a whole lot more complicated... I've assisted Governments, Individuals and Organizations throughout the world. Including; US DOJ, NHS UK, GOV UK. I'll often reblog infosec-related articles that I find interesting. On the RiSec website, You'll also find a variety of write-ups, tutorials and much more!

more infosec reads

Subscribe for weekly updates