CVE-2025-62643

Executive Summary

CVE-2025-62643 exposes a critical security flaw in the Restaurant Brands International (RBI) assistant platform, where user account passwords are transmitted in cleartext within email messages. This vulnerability, active through at least 2025-09-06, allows any party with access to the email transmission path (e.g., email server logs, network captures, or compromised email accounts) to directly retrieve plaintext passwords. The CVSS score of 3.4 reflects the low complexity of exploitation but underestimates the downstream risk of credential reuse and lateral movement. No public proof-of-concept (PoC) or exploit code has been released, and no patch is currently available.

Supply Chain & Package Security

This vulnerability is not related to an open-source package (NPM, PyPI, Go, Ruby). It is a proprietary web application platform. However, the cleartext transmission of credentials represents a fundamental failure in secure software development lifecycle (SSDLC) practices and could be exploited by attackers targeting the supply chain of RBI franchisees or partners.

CVSS Breakdown & Threat Level

• CVSS Score: 3.4 (Low)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Attack Vector (AV): Network – The attacker can exploit this over the network.
• Attack Complexity (AC): Low – No special conditions required.
• Privileges Required (PR): None – No authentication needed to intercept the email.
• User Interaction (UI): None – The victim does not need to perform any action beyond normal use.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): Low – Only password disclosure; other data not directly impacted.
• Integrity (I): None – No data modification.
• Availability (A): None – No denial of service.

Threat Level: While the CVSS score is low, the real-world impact is elevated due to the potential for credential stuffing, account takeover, and lateral movement within the RBI ecosystem. The lack of a patch makes this a persistent threat.

Deep Dive & Mechanics

The vulnerability resides in the RBI assistant platform's user account management module. When a user creates an account, resets a password, or performs any action that triggers a password-related email notification, the platform includes the plaintext password directly in the email body. This is a classic violation of secure password handling practices.

Root Cause: The application likely uses a legacy or poorly designed email notification system that retrieves the password from the database (or from the registration form) and inserts it into the email template without hashing or masking. This indicates that the application may also be storing passwords in plaintext or using reversible encryption, which is a separate but related vulnerability.

Attack Vector:

1. Email Interception: An attacker with access to the email server (e.g., via compromised SMTP credentials, man-in-the-middle on the network, or access to the user's email account) can read the plaintext password.
2. Log Analysis: Email server logs may contain the full email content, including the password, if logging is enabled.
3. Insider Threat: A malicious insider with access to email logs or the email system can harvest passwords.

Impact: Successful exploitation leads to direct account takeover of the RBI assistant platform. Given that users often reuse passwords across services, this could lead to compromise of other corporate or personal accounts.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable behavior and the expected secure implementation.

Vulnerable Code (Conceptual):

# Vulnerable email sending function
def send_password_email(user_email, password):
    subject = "Your RBI Assistant Account Password"
    body = f"Hello, your password is: {password}"
    send_email(user_email, subject, body)

Patched Code (Expected):

# Secure email sending function
def send_password_reset_email(user_email, reset_token):
    subject = "RBI Assistant Password Reset"
    body = f"Hello, use this link to reset your password: https://assistant.rbi.com/reset?token={reset_token}"
    send_email(user_email, subject, body)

The patched version should never include the password in the email. Instead, it should use a time-limited, one-time-use reset token. Additionally, passwords must be hashed (e.g., bcrypt) before storage.

Exploitation & Lab Setup

Red Team

Objective: Demonstrate interception of cleartext passwords from email traffic.

Lab Setup:

1. Environment: Use a local email server (e.g., MailHog or a test SMTP server) and a simulated RBI assistant instance.
2. Tools: Wireshark, tcpdump, or a simple SMTP sniffer.

Steps:

1. Deploy a test instance of the RBI assistant platform (if available) or simulate the vulnerable email behavior.
2. Create a user account via the platform's registration form.
3. Capture network traffic using Wireshark on the email server interface.
4. Filter for SMTP traffic (port 25, 587, or 465).
5. Follow the TCP stream to view the email content, including the plaintext password.

Example Wireshark Filter:

smtp contains "password"

Expected Output:

From: assistant@rbi.com
To: victim@example.com
Subject: Your RBI Assistant Account Password
Hello, your password is: MyP@ssw0rd!

Blue Team

Objective: Detect and prevent cleartext password transmission in emails.

Detection:

1. Email Content Scanning: Deploy an email security gateway (e.g., Proofpoint, Mimecast) with a rule to flag or block emails containing patterns like "your password is" or "password:" in the body.
2. Network Monitoring: Monitor SMTP traffic for unusual patterns or cleartext credential transmission.
3. Log Analysis: Review email server logs for any emails containing the word "password" in the subject or body.

Prevention:

1. Immediate Workaround: Disable any email notifications that include passwords. Use password reset tokens instead.
2. Code Review: Audit the application code to ensure passwords are never included in emails.
3. Password Storage: Ensure passwords are hashed using a strong algorithm (e.g., bcrypt, Argon2) and never stored in plaintext.

Indicators of Compromise (IOCs)

• Email Subject: "Your RBI Assistant Account Password" or similar variations.
• Email Body Pattern: "your password is:" followed by a plaintext string.
• SMTP Log Entries: Emails sent from assistant@rbi.com (or similar) with the subject containing "password".
• Network Traffic: SMTP sessions containing the string "password" in the DATA portion.

Detection Engineering

YARA Rule

rule CVE_2025_62643_Cleartext_Password_Email
{
    meta:
        description = "Detects emails containing cleartext passwords from RBI Assistant platform"
        author = "Valters IT"
        date = "2025-09-06"
        cve = "CVE-2025-62643"
    strings:
        $subject = /Subject:\s*Your RBI Assistant Account Password/i
        $body1 = /your password is:\s*\S+/i
        $body2 = /password:\s*\S+/i
    condition:
        $subject and ($body1 or $body2)
}

Sigma Rule

title: Cleartext Password in Email from RBI Assistant
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects emails containing cleartext passwords sent by the RBI Assistant platform
author: Valters IT
date: 2025-09-06
logsource:
    product: email
    service: smtp
detection:
    selection:
        Subject|contains: "Your RBI Assistant Account Password"
        Body|contains: "your password is:"
    condition: selection
falsepositives:
    - Legitimate password reset emails from other platforms (unlikely with exact subject)
level: high

Suricata Rule

alert smtp any any -> any any (msg:"CVE-2025-62643 - Cleartext Password in RBI Assistant Email"; content:"Subject: Your RBI Assistant Account Password"; content:"your password is:"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Password Emails: Immediately disable any email notifications that include plaintext passwords.
2. Implement Password Reset Tokens: Replace password-in-email with a secure, time-limited reset link.
3. Force Password Reset: Require all users to change their passwords immediately, as they may have been exposed.
4. Audit Email Logs: Check email server logs for any unauthorized access or leaked passwords.

Long-Term Fixes:

1. Code Review: Conduct a full security audit of the application's authentication and email notification modules.
2. Secure Password Storage: Ensure passwords are hashed using bcrypt or Argon2.
3. Encrypt Email Communications: Use TLS for all SMTP communications.
4. User Education: Inform users about the risk and advise them to change passwords on other services if reused.

Vendor Contact: Since no patch is available, contact Restaurant Brands International security team immediately and escalate through appropriate channels.

Valters IT