Bug Bounty Hunting Essentials

5 (3 reviews total)
By Carlos A. Lozano , Shahmeer Amir
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    Basics of Bug Bounty Hunting

About this book

Bug bounty programs are the deals offered by prominent companies where-in any white-hat hacker can find bugs in the applications and they will have a recognition for the same. The number of prominent organizations having this program has increased gradually leading to a lot of opportunity for Ethical Hackers.

This book will initially start with introducing you to the concept of Bug Bounty hunting. Then we will dig deeper into concepts of vulnerabilities and analysis such as HTML injection, CRLF injection and so on. Towards the end of the book, we will get hands-on experience working with different tools used for bug hunting and various blogs and communities to be followed.

This book will get you started with bug bounty hunting and its fundamentals.

Publication date:
November 2018


Chapter 1. Basics of Bug Bounty Hunting

Bug bounty hunting is a method for finding flaws and vulnerabilities in web applications; application vendors reward bounties, and so the bug bounty hunter can earn money in the process of doing so. Application vendors pay hackers to detect and identify vulnerabilities in their software, web applications, and mobile applications. Whether it's a small or a large organization, internal security teams require an external audit from other real-world hackers to test their applications for them. That is the reason they approach vulnerability coordination platforms to provide them with private contractors, also known as bug bounty hunters, to assist them in this regard.

Bug bounty hunters possess a wide range of skills that they use to test applications of different vendors and expose security loopholes in them. Then they produce vulnerability reports and send them to the company that owns the program to fix those flaws quickly. If the report is accepted by the company, the reporter gets paid. There are a few hackers who earn thousands of dollars in a single year by just hunting for vulnerabilities in programs.

The bug bounty program, also known as the vulnerability rewards program (VRP), is a crowd-sourced mechanism that allows companies to pay hackers individually for their work in identifying vulnerabilities in their software. The bug bounty program can be incorporated into an organization's procedures to facilitate its security audits and vulnerability assessments so that it complements the overall information security strategy. Nowadays, there are a number of software and application vendors that have formed their own bug bounty programs, and they reward hackers who find vulnerabilities in their programs.

The bug bounty reports sent to the teams must have substantial information with proof of concept regarding the vulnerability so that the program owners can replicate the vulnerability as per how the researcher found it. Usually the rewards are subject to the size of the organization, the level of effort put in to identify the vulnerability, the severity of the vulnerability, and the effects on the users.

Statistics state that companies pay more for bugs with high severity than with normal ones. Facebook has paid up to 20,000 USD for a single bug report. Google has a collective record of paying 700,000 USD to researchers who reported vulnerabilities to them. Similarly, Mozilla pays up to 3,000 USD for vulnerabilities. A researcher from the UK called James Forshaw was rewarded 100,000 USD for identifying a vulnerability in Windows 8.1. In 2016, Apple also announced rewards up to 200,000 USD to find flaws in iOS components, such as remote execution with kernel privileges or unauthorized iCloud access.

In this chapter, we will cover the following topics:

  • Bug bounty hunting platforms
  • Types of bug bounty programs
  • Bug bounty hunter statistics
  • Bug bounty hunting methodology
  • How to become a bug bounty hunter
  • Rules of bug bounty hunting



Bug bounty hunting platforms

A few years ago, if someone found a vulnerability in a website, it was not easy to find the right method to contact the web application owners and then too after contacting them it was not guaranteed that they would respond in time or even at all. Then there was also the factor of the web application owners threatening to sue the reporter. All of these problems were solved by vulnerability co-ordination platforms or bug bounty platforms. A bug bounty platform is a platform that manages programs for different companies. The management includes:

  • Reports
  • Communication
  • Reward payments

There are a number of different bug bounty platforms being used by companies nowadays. The top six platforms are explained in the following sections.


HackerOne is a vulnerability collaboration and bug bounty hunting platform that connects companies with hackers. It was one of the first start-ups to commercialize and utilize crowd-sourced security and hackers as a part of its business model, and is the biggest cybersecurity firm of its kind.


Bugcrowd Inc. is a company that develops a coordination platform that connects businesses with researchers so as to test their applications. It offers testing solutions for web, mobile, source code, and client-side applications.


Cobalt's Penetration Testing as a Service (PTaaS) platform converts broken pentest models into a data-driven vulnerability co-ordination engine. Cobalt's crowdsourced SaaS platform delivers results that help agile teams to pinpoint, track, and remediate vulnerabilities.


Synack is an American technology company based in Redwood City, California. Synack's business includes a vulnerability intelligence platform that automates the discovery of exploitable vulnerabilities for reconnaissance and turns them over to the company's freelance hackers to create vulnerability reports for clients.


Types of bug bounty program

Bug bounty programs come in two different types based on their participation perspectives. This division is based on the bug bounty hunter's statistics and their level of indulgence overall on a platform. There are two kinds of bug bounty program: public programs and private programs.


Public programs

A public bug bounty program is one that is open to anyone who wants to participate. This program may prohibit some researchers from participating based on the researcher's level and track record, but in general, anyone can participate in a public bounty program and this includes the scope, the rules of engagement, as well as the bounty guidelines. A public program is accessible by all researchers on the platform, and all bug bounty programs outside of the platforms are also considered bug bounty programs.

Private programs

A private bug bounty program is one that is an invite-only program for selected researchers. This is a program that allows only a few researchers to participate and the researchers are invited based on their skill level and statistics. Private programs only select those researchers who are skilled in testing the kinds of applications that they have. The programs tend to go public after a certain amount of time but some of them may never go public at all. These programs provide access only to those researchers that have a strong track record of reporting good vulnerabilities, so to be invited to good programs, it is required to have a strong and positive record.

There are a few differences between a public and private program. Conventionally, programs tend to start as private and over time evolve into the public. This is not always true but, mostly, businesses start a private bug bounty program and invite a group of researchers that test their apps before the program goes public to the community. Companies usually consider a few factors before they start a public program. There has to be a defined testing timeline and it is advised that companies initially work with researchers who specialize in that particular area to identify the flaws and vulnerabilities.

Most of the time, the companies do not open their programs to the public and limit the scope of testing as well so as to allow researchers to test these applications specifically in the sections that are critical. This reduces the number of low-severity vulnerabilities in out-of-scope applications. Many organizations use this technique to verify their security posture. Many researchers hunt for bugs in applications mainly for financial gain, so it is crucial that the organization outlines their payout structure within the program's scope. There are a few questions before anyone would want to start to participate in a bug bounty program; the most important one is What is the end goal of the program going public versus keeping it private?




Bug bounty hunter statistics

A bug bounty hunter's profile contains substantial information about the track record that helps organizations identify the skill level and skill set of the user. The bug bounty hunter stats include a number of pointers in the profile that indicate the level of the researcher. Different pointers indicate different levels on different platforms. But generally you will see the following pointers and indicators based on which you can judge a researcher's potential.

Number of vulnerabilities

The first thing you can observe in a researcher's profile is how many vulnerabilities the researcher has reported in his bug bounty hunting career. This indicated how much the researcher is active on the platform and how many vulnerabilities he has reported to date. A high number of reported vulnerabilities does not usually mean that the researcher has a positive track record and is relative to different factors. That is, if the researcher has 1,000 vulnerabilities submitted over a period of 1 year, the researcher is quite active.

Number of halls of fame

This is the number of programs to which the researcher has reported positive vulnerabilities to. The number of halls of fame is the number of programs the researcher participated in and had valid reports in those programs. A high number of programs means the level of participation of the researcher is active. That is, if the researcher has 150 halls of fame out of a total of 170 programs, the researcher is successful.

Reputation points

This is a relatively new indicator and it differs from platform to platform. Reputation points are points awarded for valid reports. It is a combination of the severity of the report, the bounty awarded to the report, and the bonus bounty of the report. That is, if the researcher has 8,000 reputation points over time, then he is above average.



A signal is an aggregate representation of report validity. It is basically a point-based system that represents how many invalid reports the researcher has submitted. A signal is calculated out of 10.


Impact is a representation of the average bounty awarded per report. It is an aggregate of the total bounty that was awarded for every report that was filed.


This is a percent-based system that indicates the number of accepted reports divided by the number of total reports. This tells the program owners how much success rate the researcher has in reporting vulnerabilities. If researcher A has 91% accuracy rate, he submits reports that are mostly valid.


Bug bounty hunting methodology

Every bug bounty hunter has a different methodology for hunting vulnerabilities and it normally varies from person to person. It takes a while for a researcher to develop their own methodology and lots of experimentation as well. However, once you get the hang of it, it is a self-driven process. The methodology of bug bounty hunting that I usually follow looks something like this:

  1. Analyzing the scope of the program: The scope guidelines have been clearly discussed in the previous chapters. This is the basic task that has to be done. The scope is the most important aspect of a bug bounty program because it tells you which assets to test and you don't want to spend time testing out-of-scope domains. The scope also tells you which are the most recent targets and which are the ones that can be tested to speed up your bounty process.
  2. Looking for valid targets: Sometimes the program does not necessarily have the entire infrastructure in its scope and there are just a number of apps or domains that are in the scope of the program. Valid targets are targets that help you quickly test for vulnerabilities in the scope and reduce time wasting.
  1. High-level testing of discovered targets: The next thing to do is a quick overview of targets. This is usually done via automated scanning. This basically tells the researchers whether the targets have been tested before or have they been tested a long time ago. If automated scanning does not reveal vulnerabilities or flaws within a web application or a mobile application, it is likely that the application has been tested by researchers before. Nonetheless, it is still advised to test that application one way or another, as this reveals the application's flaws in detail.
  2. Reviewing all applications: This is a stage where you review all the applications and select the ones based on your skill set. For instance, Google has a number of applications; some of them are coded in Ruby on Rails, some of them are coded in Python. Doing a brief recon on each application of Google will reveal which application is worth testing based on your skill set and level of experience. The method of reviewing all the applications is mostly information gathering and reconnaissance.
  3. Fuzzing for errors to expose flaws: Fuzzing is termed as iteration; the fastest way to hack an application is to test all of its input parameters. Fuzzing takes place at the input parameters and is a method of iterating different payloads at different parameters to observe responses. When testing for SQL injection vulnerabilities and cross-site scripting vulnerabilities, fuzzing is the most powerful method to learn about errors and exposure of flaws. It is also used to map an application's backend structure.
  4. Exploiting vulnerabilities to generate POCs: By fuzzing, we identify the vulnerabilities. In other scenarios, vulnerability identification is just one aspect of it. In bug bounty hunting, vulnerabilities have to be exploited constructively to generate strong proof of concepts so that the report is considered in high regard. A well explained the proof of concepts will accelerate the review process. In conventional penetration tests, vulnerability exploitation is not that important, but in bug bounty hunting, the stronger the proof of concept, the better the reward.

How to become a bug bounty hunter

Interestingly, a bug hunter is the reporter who is rewarded for finding out the vulnerabilities in websites and software. No certification or qualification is required to become a bug bounty hunter but the architecture of the application and the security issues in applications should be read thoroughly. Becoming a bug hunter is also not a matter of age, so get that out of the way.


To become a bug hunter, the crucial aspect is to learn about web application technologies and mobile application technologies. These are the things that will kick-start your career as a bug bounty hunter. Usually, if you form a team with a friend, it will help you bounce off ideas and work more closely with them in order to produce better reports and results

Bug bounty hunting is considered to be a desirable skill nowadays and it is the highest paid skill as well. A bug bounty hunter conventionally makes more than a software developer. It is advised to start small. Instead of finding and hitting large programs, start off with smaller programs and try to find vulnerabilities and bugs. When you are done with several little code and programs, then you may move on to some bigger programs. But do not jump over the software managing the entire company, despite some moderate sized software.

Reading books

There are many books available online to guide and help you in learning the basics and fundamentals of penetration testing and bug hunting. As bug bounties generally are about to comprise website targets, it is advised to start with website hacking and then move forward. It is essential to focus on the interesting and exciting area of hacking.

Practicing what you learned

At the time of learning, it is crucial that you understand and retain whatever you learn. Practice what you have learned in real time. Vulnerable applications and systems are great ways to test your skill set in virtual environments. This will also provide you with an estimate of what you are going to contribute in the real world.

Reading proof of concepts

Following the tips, by now you may have acquired a brief understanding of how to look for and deal with security vulnerabilities. So, the next step is to check what other bug bounty hunters are finding out and working on. Fortunately, the security community is pretty generous in sharing knowledge and a list of write-ups and tutorials is available to enhance your understanding. This can be done by viewing reports.


Learning from reports

By time you read POCs, you are almost about to start bug bounty hunting. But to start off with bug bounty hunting, you need to learn how the bug bounties work and how to get started with the procedure. This is done in order to assure and maximize the chances of success. Here are some resources that you can learn from:

  • H1 nobbed
  • Facebook's disclosure blog
  • Jack Whitton's blog
  • Frans Rosen's blog
  • Rafay Baloch's blog

Starting bug bounty hunting

When you are new or at a beginner level, then it is suggested not to try to hack the most public and common bugs. If you start off with hacking Microsoft, Google, Facebook, and other popular platforms, it is likely that you will end up frustrated because these sites are secure, as they have received and resolved many bug reports. Instead of targeting such sites, try to focus on the bounties that go ignored and unnoticed by other hackers and hunters.

Learning and networking with others

The most exciting thing about hacking is that it is a long journey of learning. There is always something new and interesting going around about hacking. A number of new articles and presentations are always available to learn from. There are many interesting people and experts to meet at conferences which, creates more opportunities to pursue in this field.


Rules of bug bounty hunting

We will study the rules of bug bounty hunting in the following sections.


Targeting the right program

Targeting a bug is not a matter of luck. Instead, it is considered to be a matter of skills and luck. Don't waste time on finding the already reported bugs. Otherwise, you may end up being depressed by the duplication. It is suggested to spend time on understanding the functionality of the application. Also, try making notes and have a track of suspicious endpoints. You are not going to earn a satisfactory amount for the known issues if you are too early or the first one to report. If you get to know about a program within 10 to 12 hours of its launch, don't waste your time in looking for the issues at the surface level; rather, take a deep dive into the application.

Approaching the target with clarity

If you are inspecting for vulnerabilities such as CSRF, XSS, subdomains, and so on, then you may end up getting several duplicates or not getting any bug at all. It is suggested to first check their documentation and then understand the functionalities and privileges of target users.

Keeping your expectations low

Don't expect any specific reward after reporting the bug. So, whenever you report a bug, close the report and start looking for other bugs and vulnerabilities. Develop a mindset of hunting bugs instead of hunting bugs in a matter of hours.

Learning about vulnerabilities

A pretty common scenario is that a lot of new bounty hunters just start searching for bugs without having a basic knowledge of how things work. As far as my personal experience is concerned, you will not get to know how an application works and the flow of the application until and unless you know how it is built. It is vital to know how the application is built in a programming language before you start breaking it.

Keeping yourself up-to-date

  1. Create a Twitter handle and go to the HackerOne leaderboard: https://hackerone.com/leaderboard/all-time.
  2. Go to their HackerOne profile one by one and follow them on Twitter. Keep on marking their pages.
  3. Read the HackerOne disclosed activity at http://h1.nobbd.de/.
  4. Join Bug Bounty World on Slack and keep reading their blogs, tools, general channels, and their conversations about testing, and share what you know.

Automating your vulnerabilities

In order to automate your vulnerabilities, you need to learn scripting and learning a programming language is highly recommended. JS, Python, Ruby, Bash, and so on. are some of the best scripting languages that even know some curl tricks for basic bash commands scripting.

Gaining experience with bug bounty hunting

It is saddening when a bug hunter receives no bounty. However, getting no bounty adds to experience and knowledge. You can always take bug bounty hunting in a positive way and motivate yourself.

Chaining vulnerabilities

Whenever you identify a vulnerability, the foremost question should be, what security impact is the bug going to make on the application? You can either start hunting with the goal of finding a bug or you can start hunting with a vision of looking for the best impact in the application. The former vision is an isolated one, whereas, the latter upholds a wider point of view.



In this chapter, we learned about the basics of bug bounty hunting, including the concepts of different aspects of a bug bounty program. We learned how you should engage with a bug bounty program and the platforms that you should engage with. We learned the difference between public and private bug bounty programs and about bug bounty hunter statistics.

We learned about a formulated methodology to hunt in bug bounty programs and a roadmap on how to become a bug bounty hunter, including some rules and pointers on how to work on and with bug bounty programs. This chapter is essential as it provides a basis for the chapters to come in the future. It is crucial that you go through this chapter more than once to learn deeply about what it has to say.

About the Authors

  • Carlos A. Lozano

    Carlos A. Lozano is a security consultant with more than 15 years' experience in various security fields. He has worked as a penetration tester, but most of his experience is with security application assessments. He has assessed financial applications, ISC/SCADA systems, and even low-level applications, such as drivers and embedded components. Two years ago, he started on public and private bug bounty programs and focused on web applications, source code review, and reversing projects. Also, Carlos works as Chief Operations Officer at Global CyberSec, an information security firm based in Mexico, with operations in the USA and Chile.

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  • Shahmeer Amir

    Shahmeer Amir is ranked as the third most accomplished bug hunter worldwide and has helped more than 400 organizations, including Facebook, Microsoft, Yahoo, and Twitter, resolve critical security issues in their systems. Following his vision of a safer internet, Shahmeer Amir is the founder and CEO of a cyber security start-up in Pakistan, Veiliux, aiming to secure all kinds of organizations. Shahmeer also holds relevant certifications in the field of cyber security from renowned organizations such as EC-Council, Mile2, and ELearn Security. By profession, Shahmeer is an electrical engineer working on different IoT products to make the lives of people easier.

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Latest Reviews

(3 reviews total)
Information is real world examples. Great for my bug hunting job.
Decent book, covers a lot of the importance such as report quality.
good explain book are easy to understand

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