How to find a Race-condition Bug and make $1300

1. What is a Race Condition Bug?

A race condition occurs when two or more operations attempt to execute simultaneously and rely on shared resources or data, resulting in unpredictable behavior. In a web application context, race conditions usually happen when multiple requests are processed concurrently without sufficient checks, allowing users to perform actions like doubling a purchase or transferring more funds than intended.

For example, let’s say a user is transferring $100 from one account to another. If two requests for the transfer are executed at the same time, it could result in a double transfer, even though the account only had enough funds for one.

2. How to Find Race Condition Bugs

Race condition bugs often require specialized testing and some creativity to exploit. Here’s a step-by-step approach to finding these bugs:

Understand the Functionality: Identify features in the application where users can initiate concurrent requests, like payment transactions, fund transfers, or balance updates.Look for API Endpoints Handling Sensitive Operations: Focus on endpoints that update resources, modify states, or handle financial transactions. Race conditions are often found here because of their reliance on shared data.Use Burp Suite Intruder for Automated Requests: You can exploit race conditions by sending multiple concurrent requests to the same endpoint, and Burp Suite Intruder’s attack types (such as pitchfork and battering ram) are excellent for this.Test for Inconsistent Application Responses: When sending concurrent requests, monitor for unexpected responses like duplicate transactions, incorrect balances, or even system errors.

3. Tools for Detecting Race Condition Bugs

Several tools and methods can assist in uncovering race condition vulnerabilities:

Burp Suite Intruder: Burp’s Intruder is effective for sending a large number of concurrent requests, which can simulate a race condition. Set up the Intruder to send requests in rapid succession to test if the application mishandles them.ffuf: A fast web fuzzer written in Go, ffuf is excellent for automated testing and brute-forcing, making it useful for checking the behavior of endpoints under concurrent requests.Turbo Intruder: This Burp Suite extension is tailored for detecting race conditions and can send requests with extremely high concurrency, helping to expose vulnerabilities.Race the Web: This specialized tool for detecting race conditions provides the ability to configure multiple requests and monitor for unexpected behaviors due to race conditions.

4. How to Approach Race Condition Bugs

Finding race condition bugs requires a unique mindset, as they don’t manifest like typical vulnerabilities:

Isolate Vulnerable Endpoints: Identify any endpoints that process critical data and operations sensitive to timing.Prepare Concurrent Payloads: If you’re testing a payment transaction, for example, prepare payloads that trigger the transaction multiple times and send them at nearly the same time.Analyze the Results: Look for duplicated or unexpected outcomes. Successful exploitation could lead to transactions being processed twice or unauthorized balance alterations.Report the Bug with Clear Reproduction Steps: Race condition bugs are often tricky to reproduce, so documenting the steps, payloads, and timing requirements in detail can help the bug triaging team replicate the issue.

5. Potential Earnings from Reporting Race Condition Bugs

Race condition bugs are generally rated as critical vulnerabilities because they can compromise the integrity of application functions and data. Here’s a breakdown of potential earnings:

Small Programs: Smaller programs or platforms may offer payouts between $500 — $2,000 for race condition bugs.Medium to Large Programs: Well-funded companies typically offer $5,000 — $10,000 for severe race condition bugs, especially if they impact financial transactions or sensitive user data.High-Impact Race Conditions: Race conditions that allow large-scale exploitation, such as manipulating account balances or bypassing security checks, may earn bounties as high as $20,000 or more, especially on platforms like Bugcrowd, HackerOne, or Synack.Please calp if you like it.