CVE-2025-62651

Executive Summary

CVE-2025-62651 exposes a critical access control flaw in the Restaurant Brands International (RBI) assistant platform, affecting all deployments through 2025-09-06. The vulnerability allows any unauthenticated attacker to interact with the bathroom rating interface without proper authorization checks. This can lead to unauthorized data manipulation, privacy violations, and potential reputational damage for RBI. The CVSS score of 6.5 (Medium) reflects the ease of exploitation and the lack of authentication required, though the impact is limited to confidentiality and integrity of the rating data. No public exploit code or proof-of-concept is available, but the risk remains significant due to the absence of a patch.

Supply Chain & Package Security

This vulnerability is not related to any open-source package manager (NPM, PyPI, Go, Ruby). It is a custom web application component of the RBI assistant platform. No supply chain attack vector is identified.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – no authentication needed.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – limited exposure of rating data.
• Integrity Impact: Low (I:L) – ability to modify ratings.
• Availability Impact: None (A:N) – no denial-of-service risk.

Threat Level: Medium. The vulnerability is easy to exploit but has limited direct impact. However, it could be chained with other flaws for larger attacks.

Deep Dive & Mechanics

The RBI assistant platform includes a bathroom rating interface that allows users to submit and view ratings for restroom facilities. The vulnerability stems from the absence of access control checks on the API endpoints handling these ratings. Specifically, the server does not validate whether the requester is authenticated or authorized to perform actions such as submitting, modifying, or viewing ratings.

Root Cause: The application fails to enforce any authentication or authorization middleware on the bathroom rating endpoints. This is a classic case of Missing Authorization (CWE-862). The endpoints likely rely on client-side checks or assume that only legitimate users will access them, which is a flawed security model.

Attack Vector: An attacker can directly send HTTP requests to the bathroom rating API endpoints (e.g., /api/bathroom/rate, /api/bathroom/ratings) without any session token or API key. The server processes these requests as if they came from an authenticated user.

Potential Impact:

• Data Manipulation: Attackers can submit fake ratings, skewing the overall score.
• Data Exposure: Unauthorized access to all submitted ratings, potentially including user metadata.
• Reputational Damage: Manipulated ratings could mislead customers and harm RBI’s brand.

Vulnerable vs. Patched Code

Since no patch is available, the following illustrates the vulnerable pattern and a hypothetical secure implementation.

Vulnerable Code (Python Flask example):

@app.route('/api/bathroom/rate', methods=['POST'])
def submit_rating():
    data = request.get_json()
    # No authentication check
    rating = data.get('rating')
    bathroom_id = data.get('bathroom_id')
    # Save to database
    db.save_rating(bathroom_id, rating)
    return jsonify({"status": "success"}), 200

Patched Code (Hypothetical):

from flask import request, jsonify, g
from functools import wraps

def require_auth(f):
    @wraps(f)
    def decorated(*args, **kwargs):
        token = request.headers.get('Authorization')
        if not token or not validate_token(token):
            return jsonify({"error": "Unauthorized"}), 401
        g.user = get_user_from_token(token)
        return f(*args, **kwargs)
    return decorated

@app.route('/api/bathroom/rate', methods=['POST'])
@require_auth
def submit_rating():
    data = request.get_json()
    rating = data.get('rating')
    bathroom_id = data.get('bathroom_id')
    # Additional authorization check (e.g., user role)
    if not g.user.can_rate(bathroom_id):
        return jsonify({"error": "Forbidden"}), 403
    db.save_rating(bathroom_id, rating, g.user.id)
    return jsonify({"status": "success"}), 200

Exploitation & Lab Setup

Red Team

Objective: Demonstrate unauthorized access to the bathroom rating interface.

Prerequisites:

• Target URL of an RBI assistant platform instance (e.g., https://assistant.rbi.com).
• No authentication credentials required.

Steps:

1. Identify the bathroom rating API endpoint. Common patterns include:
   • POST /api/bathroom/rate
   • GET /api/bathroom/ratings
   • POST /api/v1/bathroom/rate
2. Send a direct request using curl:

   curl -X POST https://assistant.rbi.com/api/bathroom/rate \
     -H "Content-Type: application/json" \
     -d '{"bathroom_id": "123", "rating": 5}'
   

3. Observe the response. If successful (HTTP 200), the vulnerability is confirmed.
4. To read existing ratings:

   curl https://assistant.rbi.com/api/bathroom/ratings
   

Expected Outcome: The server returns a success response without requiring any authentication token.

Blue Team

Objective: Detect and block unauthorized access attempts.

Detection Strategy:

• Monitor for requests to bathroom rating endpoints that lack an Authorization header or contain invalid tokens.
• Alert on high volumes of rating submissions from a single IP in a short period.
• Implement rate limiting on all API endpoints.

Hunting Query (Splunk):

index=web_logs sourcetype=access_combined
| search uri_path IN ("/api/bathroom/rate", "/api/bathroom/ratings")
| eval has_auth=if(isnull(authorization_header), "no", "yes")
| where has_auth="no"
| stats count by src_ip, uri_path
| where count > 10

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /api/bathroom/rate or /api/bathroom/ratings without an Authorization header.
  • Repeated POST requests with JSON payloads containing bathroom_id and rating fields.
• File IOCs:
  • Log entries showing 200 responses to unauthenticated API calls.
• Behavioral IOCs:
  • Sudden spikes in rating submissions for a single bathroom ID.
  • Ratings from IP addresses not associated with known users.

Detection Engineering

YARA Rule

rule CVE_2025_62651_Bathroom_Rating_Exploit {
    meta:
        description = "Detects HTTP requests targeting the unauthenticated bathroom rating API"
        author = "Valters IT"
        date = "2025-09-06"
        cve = "CVE-2025-62651"
    strings:
        $api_path = "/api/bathroom/rate" nocase
        $api_path2 = "/api/bathroom/ratings" nocase
        $json_rating = "rating" nocase
        $json_bathroom = "bathroom_id" nocase
    condition:
        any of ($api_path, $api_path2) and any of ($json_rating, $json_bathroom)
}

Sigma Rule

title: Unauthenticated Access to RBI Bathroom Rating API
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests to the bathroom rating API without authentication
author: Valters IT
date: 2025-09-06
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-path:
            - "/api/bathroom/rate"
            - "/api/bathroom/ratings"
        cs-auth-type: "none"
    condition: selection
falsepositives:
    - Legitimate unauthenticated health checks (if any)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-62651 - Unauthenticated Bathroom Rating API Access"; flow:to_server; content:"/api/bathroom/rate"; http_uri; nocase; content:"rating"; http_client_body; nocase; content:"bathroom_id"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Implement Authentication: Add token-based or session-based authentication to all bathroom rating endpoints. Use OAuth 2.0 or JWT for stateless verification.
2. Apply Authorization Checks: Ensure that only authorized users (e.g., authenticated customers or employees) can submit or view ratings.
3. Rate Limiting: Enforce strict rate limits on rating submissions to prevent abuse.
4. Input Validation: Validate all input fields to prevent injection attacks.

Long-Term Fixes:

• Conduct a full security audit of the RBI assistant platform to identify similar missing access controls.
• Adopt a security-by-design approach, embedding authentication and authorization in the development lifecycle.
• Deploy a Web Application Firewall (WAF) with rules to block unauthenticated API calls.

Workaround (if patching is delayed):

• Disable the bathroom rating interface entirely until a fix is deployed.
• Restrict access to the API endpoints via network-level controls (e.g., IP whitelisting) if the feature is only used internally.

Valters IT