CVE-2024-27928

Executive Summary

CVE-2024-27928 is a vulnerability in the vantage6 open-source infrastructure for privacy-preserving analysis. The flaw allows an attacker who has compromised a user's email account to bypass two-factor authentication (2FA) by resetting both the password and the 2FA token via email. This effectively reduces 2FA to single-factor authentication (email access). While the attack requires prior compromise of the email account, it undermines the security guarantees of 2FA. The vulnerability is rated with a CVSS score of 0.0 in the NVD, but based on the impact, a more realistic score is 7.1 (High). The vendor has released version 5.0.0 to address this issue.

Supply Chain & Package Security

This vulnerability affects the vantage6 Python package ecosystem. Organizations using vantage6 should verify they are not using a vulnerable version (< 5.0.0) and update immediately. The package is distributed via PyPI, and the fix is available in version 5.0.0.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attack is initiated over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker needs access to the user's email account.
• User Interaction (UI): Required (R) – The user must have an active session or the attacker must trigger the reset.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Full access to user data.
• Integrity (I): High (H) – Full ability to modify user data.
• Availability (A): None (N) – No impact on availability.

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
Base Score: 7.1 (High)

Deep Dive & Mechanics

The vulnerability lies in the password reset and 2FA token reset functionality of vantage6. The application allows users to reset their password via email, and also allows resetting the 2FA token via email. If an attacker gains access to a user's email account, they can:

1. Initiate a password reset request.
2. Receive the password reset link via email.
3. Reset the password.
4. Initiate a 2FA token reset request.
5. Receive the 2FA token reset link via email.
6. Reset the 2FA token.

This sequence bypasses the 2FA protection, reducing it to single-factor authentication (email access). The vulnerability is present in versions prior to 5.0.0.

Vulnerable vs. Patched Code

Vulnerable Code (Pre-5.0.0): The password reset and 2FA token reset endpoints likely do not require additional verification beyond the email link. For example, the password reset endpoint might accept a token from the email without checking if the user has an active session or if the request was initiated by the user.

# Vulnerable example (pseudo-code)
@app.route('/reset_password', methods=['POST'])
def reset_password():
    token = request.form['token']
    user = verify_reset_token(token)
    if user:
        user.password = hash_password(request.form['new_password'])
        user.save()
        return "Password reset successful"

Patched Code (5.0.0+): The patched version likely requires additional verification, such as requiring the user to confirm the reset via a separate channel or requiring the user to be logged in to initiate the reset.

# Patched example (pseudo-code)
@app.route('/reset_password', methods=['POST'])
def reset_password():
    token = request.form['token']
    user = verify_reset_token(token)
    if user and user.is_authenticated:
        user.password = hash_password(request.form['new_password'])
        user.save()
        return "Password reset successful"
    else:
        return "Unauthorized", 401

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to the victim's email account (e.g., via phishing, credential stuffing, or email account compromise).
• Knowledge of the vantage6 server URL.

Exploitation Steps:

1. Access the victim's email account.
2. Navigate to the vantage6 login page.
3. Click "Forgot password" and enter the victim's email address.
4. Check the victim's email for the password reset link.
5. Click the link and set a new password.
6. Log in with the new password (2FA will be prompted).
7. Click "Reset 2FA" or similar option.
8. Check the victim's email for the 2FA reset link.
9. Click the link and set a new 2FA token (or disable 2FA).
10. Log in with the new password and bypass 2FA.

No exploit code is available for this CVE.

Blue Team

Detection:

• Monitor for multiple password reset requests from the same IP or user agent.
• Monitor for password resets followed immediately by 2FA resets.
• Alert on password resets that occur outside of normal business hours.
• Monitor for login attempts from new devices or locations after a password reset.

Prevention:

• Enforce multi-factor authentication for email accounts.
• Implement rate limiting on password reset and 2FA reset endpoints.
• Require additional verification (e.g., security questions, SMS code) for password and 2FA resets.
• Monitor and alert on suspicious email account activity.

Indicators of Compromise (IOCs)

• Email Account Compromise: Unusual login locations, times, or devices for the victim's email account.
• Password Reset Requests: Multiple password reset requests for the same user in a short period.
• 2FA Reset Requests: 2FA reset requests immediately following a password reset.
• New Login Sessions: Login sessions from new IP addresses or user agents after a password reset.

Detection Engineering

YARA Rule

rule CVE_2024_27928_vantage6_password_reset {
    meta:
        description = "Detects potential exploitation of CVE-2024-27928 by monitoring for password reset and 2FA reset patterns"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-27928"
    strings:
        $password_reset = "reset_password" nocase
        $twofa_reset = "reset_2fa" nocase
        $email_link = "email" nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2024-27928 - Password and 2FA Reset Abuse
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-27928 by monitoring for password reset and 2FA reset requests
author: Valters IT
date: 2024-01-01
logsource:
    category: application
    product: vantage6
detection:
    selection:
        event: "password_reset"
    condition: selection
    timeframe: 5m
    aggregation:
        field: user
        function: count
        condition: gt 3
falsepositives:
    - Legitimate password resets
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-27928 - vantage6 Password Reset Attempt"; flow:to_server; content:"POST"; http_method; content:"/reset_password"; http_uri; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2024-27928 - vantage6 2FA Reset Attempt"; flow:to_server; content:"POST"; http_method; content:"/reset_2fa"; http_uri; sid:1000002; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade vantage6 to version 5.0.0 or later.
2. Ensure all user email accounts have 2FA enabled.
3. Monitor for suspicious password and 2FA reset activity.

Long-term Mitigations:

• Implement additional verification steps for password and 2FA resets (e.g., requiring the user to confirm via a separate channel).
• Enforce strong password policies and regular password changes.
• Conduct security awareness training to prevent email account compromise.

Valters IT