CVE-2025-15626

Executive Summary

CVE-2025-15626 is an authorization bypass vulnerability in the Ribblr iOS application for crochet and knitting. The flaw allows an authenticated user to bypass authorization controls, potentially accessing resources or performing actions beyond their intended privilege level. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), and no EPSS score, exploit code, or patch information is currently available. The vendor, Ribblr, has not released a patch, and the vulnerability remains unpatched.

Supply Chain & Package Security

This vulnerability affects a mobile iOS application distributed via the Apple App Store. While not a traditional package manager ecosystem (NPM, PyPI, Go, Ruby), the application may rely on third-party libraries and SDKs. The authorization bypass could stem from insecure implementation of role-based access control (RBAC) or improper session handling within the app's backend API. Supply chain risks include compromised dependencies used for authentication or authorization logic.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low (likely)
• Privileges Required (PR): Low (authenticated user)
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): High (potential access to other users' data)
• Integrity (I): High (potential to modify data)
• Availability (A): Low (unlikely to affect availability)

Threat Level: High. An authenticated user can bypass authorization, leading to unauthorized data access or actions.

Deep Dive & Mechanics

The vulnerability lies in the Ribblr iOS application's authorization mechanism. After authentication, the app likely uses a token or session identifier to authorize user actions. The flaw allows an attacker to manipulate this token or exploit missing server-side checks to access resources belonging to other users or perform administrative actions.

Potential Root Causes:

• Insecure Direct Object Reference (IDOR) in API endpoints.
• Missing or improper role/permission validation on the server side.
• Weak session management allowing token reuse or tampering.
• Client-side authorization checks that can be bypassed.

Attack Vector:

1. Authenticate as a low-privileged user.
2. Intercept API requests using a proxy (e.g., Burp Suite).
3. Modify parameters (e.g., user ID, role, resource ID) to access unauthorized data.
4. Server fails to validate the user's authorization for the requested resource.

Vulnerable vs. Patched Code

No patch is available. The vulnerable code likely resides in the backend API handling authorization. A patched version would implement server-side checks for every resource access, verifying the authenticated user's permissions against the requested action.

Vulnerable Code (Conceptual):

// Vulnerable: No server-side authorization check
app.get('/api/user/:id/profile', (req, res) => {
  const userId = req.params.id;
  // Directly returns profile without checking if req.user.id == userId
  const profile = db.getUserProfile(userId);
  res.json(profile);
});

Patched Code (Conceptual):

// Patched: Server-side authorization check
app.get('/api/user/:id/profile', (req, res) => {
  const userId = req.params.id;
  if (req.user.id !== userId && !req.user.isAdmin) {
    return res.status(403).json({ error: 'Forbidden' });
  }
  const profile = db.getUserProfile(userId);
  res.json(profile);
});

Exploitation & Lab Setup

Red Team

Prerequisites:

• A jailbroken iOS device or an iOS simulator.
• Burp Suite or mitmproxy configured to intercept traffic.
• A valid Ribblr account.

Steps:

1. Configure the iOS device to route traffic through the proxy.
2. Install the Ribblr app and authenticate.
3. Use Burp Suite to intercept API requests.
4. Identify endpoints that accept user IDs or resource IDs (e.g., /api/patterns/123).
5. Modify the ID to another user's pattern ID.
6. If the server returns data without authorization, the vulnerability is confirmed.

Example Request Modification:

GET /api/patterns/456 HTTP/1.1
Host: api.ribblr.com
Authorization: Bearer <token>

Change 456 to 789 (another user's pattern).

Blue Team

Detection:

• Monitor API logs for unusual access patterns (e.g., a single user accessing many different user IDs).
• Alert on 403 errors followed by successful access to the same resource.
• Implement rate limiting and anomaly detection on user behavior.

Mitigation:

• Enforce server-side authorization for all API endpoints.
• Use UUIDs instead of sequential IDs to reduce IDOR risk.
• Implement proper role-based access control (RBAC).
• Conduct regular security audits and penetration testing.

Indicators of Compromise (IOCs)

• Network: Unusual API requests with modified user/resource IDs.
• Logs: Repeated 403 errors followed by 200 responses for the same resource.
• Application: Unauthorized access to other users' patterns, profiles, or orders.

Example IOC (Log Entry):

{
  "timestamp": "2025-03-15T10:30:00Z",
  "user_id": "user123",
  "endpoint": "/api/patterns/456",
  "status_code": 200,
  "anomaly": true
}

Detection Engineering

YARA Rule

rule CVE_2025_15626_Ribblr_AuthBypass {
    meta:
        description = "Detects potential authorization bypass in Ribblr iOS app"
        author = "Valters IT"
        date = "2025-03-15"
        reference = "CVE-2025-15626"
    strings:
        $api_pattern = "/api/" ascii wide nocase
        $user_id_param = "user_id" ascii wide nocase
        $pattern_id_param = "pattern_id" ascii wide nocase
    condition:
        any of ($api_pattern) and (any of ($user_id_param) or any of ($pattern_id_param))
}

Sigma Rule

title: Ribblr Authorization Bypass Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential IDOR or authorization bypass in Ribblr API logs
author: Valters IT
date: 2025-03-15
logsource:
    category: application
    product: ribblr
detection:
    selection:
        endpoint|startswith: '/api/'
        status_code: 200
    filter:
        user_id|equals: 'current_user_id'  # Placeholder
    condition: selection and not filter
falsepositives:
    - Legitimate access to shared resources
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-15626 Ribblr Authorization Bypass"; flow:to_server,established; content:"/api/"; http_uri; nocase; content:"user_id"; http_uri; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable vulnerable endpoints if possible until a patch is available.
2. Implement Web Application Firewall (WAF) rules to block suspicious parameter manipulation.
3. Enforce server-side authorization for all API requests.
4. Audit user sessions and revoke tokens if abuse is detected.

Long-Term Fixes:

• Patch the application once Ribblr releases an update.
• Conduct a security review of the authentication and authorization logic.
• Implement rate limiting and anomaly detection.
• Use parameterized queries to prevent injection attacks.

Workarounds:

• Restrict API access to trusted IP ranges if possible.
• Monitor logs for unusual activity and respond promptly.

Valters IT