A Comprehensive Guide to Bug Bounty Hunting

Bug bounty hunting is a powerful method for identifying security flaws and vulnerabilities in web and mobile applications. It’s a mutually beneficial relationship: application vendors reward hackers with bounties, and in return, hackers help secure their software. This crowdsourced approach allows companies of all sizes to receive an external audit from real-world hackers, providing a crucial layer of security that internal teams might miss.

What is a Bug Bounty Program?

A bug bounty program, also known as a Vulnerability Rewards Program (VRP), is a mechanism where companies pay individual hackers for their work in identifying and reporting vulnerabilities in their software. It complements an organization’s existing security strategy by facilitating continuous security audits and vulnerability assessments. Many software and application vendors have their own dedicated bug bounty programs, and they reward hackers who find flaws in their systems.

The Value of Vulnerability Reports

To be accepted and rewarded, a bug bounty report must contain substantial information and a proof of concept (POC). The POC allows the program owners to replicate the vulnerability exactly as the researcher found it. The reward a hacker receives is typically based on several factors, including:

• The size of the organization.
• The level of effort required to identify the vulnerability.
• The severity of the vulnerability.
• The potential impact on users.

Statistics show that companies pay significantly more for high-severity bugs. For example, Facebook has paid up to $20,000 for a single bug report, while Google has paid a collective $700,000 to researchers. Mozilla also pays up to $3,000 for vulnerabilities. In 2016, Apple even announced rewards of up to $200,000 for specific flaws in iOS components, such as unauthorized iCloud access or remote code execution with kernel privileges.

Bug Bounty Hunting Platforms

Before the rise of bug bounty platforms, it was challenging for hackers to responsibly disclose vulnerabilities. Finding the right contact, ensuring a timely response, and avoiding legal threats from companies were significant hurdles. Vulnerability coordination platforms solved these problems by acting as a middleman.

A bug bounty platform manages programs for different companies, handling everything from report submissions and communication to reward payments. Some of the top platforms in the industry include:

• HackerOne: One of the first and largest platforms to commercialize and utilize crowdsourced security.
• Bugcrowd: A platform that connects businesses with researchers and offers testing solutions for web, mobile, and source code.
• Cobalt: A Penetration Testing as a Service (PTaaS) platform that focuses on providing data-driven vulnerability coordination.
• Synack: A technology company that uses a vulnerability intelligence platform to automate discovery and then assigns findings to freelance hackers for further reporting.

Types of Bug Bounty Programs

Bug bounty programs are generally categorized into two types based on their participation model: public and private programs.

Public Programs

A public bug bounty program is open to anyone who wants to participate. While some may have restrictions based on a researcher’s track record, they generally provide the scope, rules of engagement, and bounty guidelines to all researchers on the platform. Any program that is publicly accessible outside of a platform is also considered a public program.

Private Programs

A private bug bounty program is an invite-only program for selected researchers. Companies invite hackers based on their skill level and statistics, ensuring that only those skilled in testing specific types of applications are granted access. These programs often start as private and may evolve into public programs over time, but some remain private indefinitely. To get invited to these exclusive programs, a researcher must have a strong track record of reporting high-quality vulnerabilities.

The Public vs. Private Debate

Companies often start with a private program to work with a small, trusted group of specialists before opening up to the broader community. This allows them to define a clear testing timeline and limit the scope to critical areas, which helps reduce the number of low-severity reports on out-of-scope assets. For hackers, private programs often offer better rewards and less competition.

Understanding Bug Bounty Hunter Statistics

A bug bounty hunter’s profile contains key statistics that help organizations assess their skill level and track record. While different platforms may have their own unique indicators, here are some of the most common metrics used to judge a researcher’s potential:

• Number of Vulnerabilities: The total number of vulnerabilities a researcher has reported. A high number indicates activity, but doesn’t necessarily mean a positive track record.
• Halls of Fame: The number of programs where the researcher has submitted valid reports. A high number signifies broad participation and success. For example, a researcher with 150 Halls of Fame out of 170 programs is considered very successful.
• Reputation Points: A point-based system awarded for valid reports, often based on the report’s severity, bounty amount, and any bonus bounties.
• Signal: A representation of report validity, usually a score out of 10. A high signal indicates a low number of invalid reports.
• Impact: The average bounty awarded per report, representing the total bounty money received.
• Accuracy: A percentage-based system that shows the ratio of accepted reports to total reports. An accuracy rate of 91% means a researcher’s reports are almost always valid.

A Recommended Bug Bounty Hunting Methodology

Every bug bounty hunter develops their own unique methodology over time through experimentation. Here is a common, self-driven process that many follow:

1. Analyze the Program Scope: The scope is the most critical part of any program. It tells you exactly which assets to test, saving you time from testing out-of-scope domains. It also helps prioritize recent or critical targets.
2. Look for Valid Targets: Sometimes, a program’s scope only includes a few specific domains or applications. Identifying these valid targets early helps focus your efforts and maximize efficiency.
3. Perform High-Level Testing: Conduct a quick overview of targets, often using automated scanning tools. While this may not reveal new vulnerabilities in applications that have been tested before, it provides a crucial initial assessment.
4. Review All Applications: Perform information gathering and reconnaissance on all applications within the scope. This allows you to select targets based on your specific skillset. For example, if you’re skilled in Ruby on Rails, you would focus on applications built with that framework.
5. Fuzzing for Errors: Fuzzing involves iterating different payloads at an application’s input parameters to observe its responses. This is a powerful technique for exposing errors and mapping backend structures, especially for vulnerabilities like SQL injection and cross-site scripting (XSS).
6. Exploit Vulnerabilities and Generate POCs: After identifying a vulnerability through fuzzing or other methods, you must exploit it constructively to create a strong proof of concept. A well-explained POC is crucial for getting your report accepted and will often lead to a better reward.