🔐 Bug Bounty Tip: Finding Password Reset Vulnerabilities

When it comes to securing web applications, the password reset process is often one of the most vulnerable entry points for attackers. A single weakness in this flow can lead to a catastrophic breach of user accounts. As bug bounty hunters, it’s crucial to understand the common vulnerabilities that can be exploited during the password reset process and how to identify them.

In this post, I’ll walk you through key issues to look for when testing for password reset vulnerabilities. By knowing what to test for, you can help developers strengthen their systems and earn some valuable bug bounty rewards.

1️⃣ Brute-Force Vulnerabilities in Password Reset OTPs

One of the most common issues in password reset flows is a lack of rate-limiting for One-Time Passwords (OTPs). Without rate-limiting, an attacker can try an unlimited number of OTPs in a short period, potentially gaining access to user accounts.

What to test for:

• Ensure that the application imposes a rate limit on OTP attempts.
• Check if the system locks the account or introduces a delay after a certain number of failed OTP entries.

Why it matters:
Brute-forcing OTPs is a simple attack, but rate-limiting can make it significantly harder for attackers to guess the correct code.

2️⃣ Predictable Tokens

Another common vulnerability is the use of predictable password reset tokens. If a token is easy to guess or follows a predictable pattern, attackers can simply generate tokens to reset other users’ passwords.

What to test for:

• Look for patterns in the tokens (e.g., sequential numbers, short-length tokens, or tokens that appear similar for multiple users).
• Ensure that tokens are sufficiently random and long enough to resist guessing attempts.

Why it matters:
A weak or predictable token can undermine the entire password reset process, making it a prime target for attackers.

3️⃣ JWT Misconfigurations

JSON Web Tokens (JWTs) are often used to authenticate users during password resets. However, misconfigurations in JWTs can allow attackers to tamper with the token’s payload, bypassing security checks and gaining unauthorized access.

What to test for:

• Check if the JWT is signed and validated properly.
• Verify that the token’s expiration time is set correctly and cannot be tampered with.

Why it matters:
Improper JWT configurations can allow attackers to manipulate token data, leading to unauthorized access.

4️⃣ IDOR (Insecure Direct Object Reference)

IDOR vulnerabilities occur when an attacker can manipulate IDs or tokens in the URL to gain unauthorized access to other users’ data. This includes the ability to reset passwords for accounts that aren’t their own.

What to test for:

• Test if modifying the user ID or token in the password reset URL allows access to another user’s account.
• Ensure that the system validates ownership of the account before allowing a password reset.

Why it matters:
IDOR vulnerabilities expose sensitive user data and can lead to unauthorized actions on behalf of other users.

5️⃣ Host Header Injection

Host header injection is a serious issue that can redirect users to malicious sites during the password reset process. If the application doesn’t properly validate the Host header, attackers can exploit this flaw to trick users into visiting a phishing site or leak sensitive data.

What to test for:

• Ensure that the Host header is properly validated and sanitized to prevent injection attacks.
• Test if malicious host headers can cause a redirection to an external malicious website during password reset flows.

Why it matters:
An attacker-controlled host header can redirect users to phishing sites or expose sensitive information.

6️⃣ Leaked Tokens or OTPs in HTTP Responses

Tokens or OTPs that are leaked in HTTP responses or included in URLs can be intercepted and used by attackers to perform password resets or other malicious actions.

What to test for:

• Check if tokens or OTPs are exposed in URLs or HTTP responses.
• Ensure that tokens and OTPs are only available in request bodies or secure storage, never in URLs or responses.

Why it matters:
Leaked tokens and OTPs can easily be captured by attackers, compromising user accounts.

7️⃣ Proper Validation of OTPs or Tokens

OTP or token validation is critical for ensuring that the reset process is secure. Systems must not only check if the token is valid, but also if it has expired or if it has already been used.

What to test for:

• Verify that the system correctly validates the expiration of OTPs or reset tokens.
• Check if the system handles duplicate or reused tokens properly.

Why it matters:
Without proper validation, attackers can reuse expired or already-used tokens to reset passwords and gain unauthorized access.

8️⃣ HTTP Parameter Pollution (HPP)

HTTP Parameter Pollution (HPP) allows attackers to inject additional parameters into HTTP requests, potentially manipulating the password reset process or bypassing security controls.

What to test for:

• Check if the password reset flow is vulnerable to HPP attacks by injecting extra parameters in the HTTP request.
• Test how the system handles multiple occurrences of the same parameter in a single request.

Why it matters:
HPP attacks can disrupt the password reset process and cause unexpected behavior, leading to security vulnerabilities.

Conclusion

Testing for password reset vulnerabilities is an essential part of any bug bounty program. By being aware of these common security issues, you can better protect users from potential attacks and contribute to improving the overall security of web applications.

If you discover any of these vulnerabilities during your testing, make sure to report them responsibly with clear steps and context. Responsible disclosure can not only earn you bug bounties but also help make the internet a safer place for everyone.

Happy hunting! 🕵️‍♂️

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