Mail Splitting Attack in FuelCMS 1.5.2 Exposes Reset Tokens

Executive Summary

The vulnerability in Daylight Studio FuelCMS v1.5.2 allows attackers to exfiltrate users' password reset tokens by exploiting a mail splitting attack.

Specifically, the issue arises because the system improperly handles multiple email addresses submitted as an array during password reset requests. An attacker who knows or can guess a valid user's email can send a crafted request that includes both the victim's and the attacker's email addresses.

The application then sends the password reset email, containing the reset token, to both addresses. The attacker receives the token and can use it to reset the victim's password, gaining unauthorized access to their account.

This attack requires the attacker to obtain a valid session cookie and CSRF token beforehand.

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Impact Analysis

This vulnerability can lead to full account takeover of FuelCMS user accounts.

If the compromised account has administrative or editor privileges, the attacker can modify or delete any website content, severely impacting the integrity of the site.

While the confidentiality impact is considered low because the attacker only gains access to the current user's information, the integrity impact is high due to potential unauthorized changes.

Additionally, if combined with another vulnerability (PHP Code Execution via Dwoo Escape), the attacker could escalate the attack to remote code execution, making the impact critical.

No fix is currently available, increasing the risk for affected users.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious POST requests to the password reset endpoint `/index.php/fuel/login/pwd_reset` where the `email` parameter is sent as an array containing multiple email addresses.

To detect exploitation attempts, you can look for POST requests with parameters like `email[][email protected]&email[][email protected]` in your web server logs or by using network monitoring tools.

Additionally, checking for the presence of valid session cookies (`ci_session`) and CSRF tokens (`ci_csrf_token_FUEL`) in these requests can help identify potential attacks.

Example command to search web server logs for suspicious password reset requests (assuming Apache logs):

• grep 'POST /index.php/fuel/login/pwd_reset' /var/log/apache2/access.log | grep 'email%5B%5D='

You can also use tools like Wireshark or tcpdump to capture HTTP traffic and filter for POST requests to the reset endpoint containing multiple email parameters.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the password reset functionality to trusted users or IP addresses to reduce the attack surface.

Implement additional validation on the server side to reject password reset requests where the `email` parameter is an array or contains multiple email addresses.

Monitor and invalidate any suspicious password reset tokens and sessions to prevent unauthorized password changes.

Since no official fix is available and the FuelCMS master branch has not been updated for over four years, consider upgrading to a different CMS or applying custom patches to fix the email array parsing issue.

Ensure that session cookies and CSRF tokens are properly protected and not leaked to attackers.

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Compliance Impact

The vulnerability in Daylight Studio FuelCMS v1.5.2 allows attackers to exfiltrate users' password reset tokens via a mail splitting attack, leading to unauthorized account takeover. This compromises the confidentiality and integrity of user accounts.

Such unauthorized access and potential modification of user data can lead to non-compliance with data protection regulations like GDPR and HIPAA, which require safeguarding personal data and ensuring user account security.

Specifically, the exposure of password reset tokens and subsequent account takeover could result in unauthorized access to personal data, violating principles of data confidentiality and security mandated by these standards.

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