CVE-2025-13768

Executive Summary

CVE-2025-13768 is an Authentication Bypass vulnerability in the WebITR application developed by Uniong. This flaw allows an authenticated remote attacker to impersonate any user by manipulating a specific parameter during the authentication process. The attacker must first obtain a valid user ID (e.g., via enumeration or prior compromise) to exploit this vulnerability. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), but the impact is severe as it completely undermines the authentication mechanism, granting unauthorized access to all system functions and data accessible to the impersonated user. No public proof-of-concept (PoC) code or patch is currently available.

Supply Chain & Package Security

This vulnerability does not affect any known open-source package registries (NPM, PyPI, Go, Ruby). It is a proprietary web application (WebITR) developed by Uniong.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned value. Based on the vulnerability description, a realistic CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) – The attack is performed over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – The attacker must be authenticated (has a valid session) but can then escalate privileges.
• User Interaction (UI): None (N) – No user action is required.
• Scope (S): Unchanged (U) – The vulnerable component is the same as the affected component.
• Confidentiality (C): High (H) – Full access to all user data.
• Integrity (I): High (H) – Ability to modify data as the impersonated user.
• Availability (A): High (H) – Potential to disrupt service as a privileged user.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Estimated Base Score: 8.8 (High)

Threat Level: High. The vulnerability is easy to exploit (low complexity, low privileges required) and has a high impact on confidentiality, integrity, and availability.

Deep Dive & Mechanics

The vulnerability resides in the authentication logic of WebITR. The application likely uses a parameter (e.g., user_id, uid, username) to identify the user during session creation or validation. An authenticated attacker can intercept and modify this parameter in a request (e.g., via a proxy tool like Burp Suite) to impersonate another user.

Mechanism:

1. The attacker authenticates as a low-privileged user (e.g., user1).
2. The attacker obtains a valid user ID (e.g., user2's ID) through enumeration (e.g., by observing error messages, IDOR in other endpoints, or brute-forcing).
3. The attacker sends a request to a sensitive endpoint (e.g., /api/switch_user, /profile, or a session management endpoint) with the modified parameter set to user2's ID.
4. The server fails to properly validate that the attacker is authorized to assume that identity, and returns data or performs actions as user2.

This is a classic Insecure Direct Object Reference (IDOR) combined with Authentication Bypass. The root cause is insufficient server-side validation of the user identity parameter.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern.

Vulnerable Code (Conceptual - PHP/Java):

// Vulnerable: Directly uses the 'user_id' parameter without verifying ownership
$user_id = $_POST['user_id'];
$user_data = $db->query("SELECT * FROM users WHERE id = $user_id");
$_SESSION['user'] = $user_data;

Patched Code (Conceptual):

// Patched: Validates that the current session user is allowed to access the target user's data
$current_user_id = $_SESSION['user']['id'];
$target_user_id = $_POST['user_id'];

// Only allow if the target user is the same as the current user, or if the current user has admin privileges
if ($current_user_id == $target_user_id || is_admin($current_user_id)) {
    $user_data = $db->query("SELECT * FROM users WHERE id = $target_user_id");
    $_SESSION['user'] = $user_data;
} else {
    // Deny access
    http_response_code(403);
    echo "Forbidden";
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A valid user account on the WebITR application.
• A valid user ID of the target user (e.g., obtained via enumeration or IDOR).

Exploitation Steps:

1. Log in as a low-privileged user (e.g., attacker).
2. Intercept a request to a sensitive endpoint (e.g., /profile, /api/user_data, or a session switch endpoint).
3. Modify the parameter that identifies the user (e.g., user_id, uid, username) to the target user's ID.
4. Forward the request.
5. The server responds with the target user's data or performs actions as the target user.

Example Request (Burp Suite):

POST /api/get_user_data HTTP/1.1
Host: webitr.example.com
Cookie: session=attacker_session_token
Content-Type: application/x-www-form-urlencoded

user_id=12345&action=view

Replace 12345 with the target user's ID.

Lab Setup:

• Install WebITR on a local server (if available).
• Create multiple user accounts (e.g., user1, user2).
• Use Burp Suite or OWASP ZAP to intercept and modify requests.

Blue Team (Detection & Defense)

Detection:

• Monitor for anomalous parameter manipulation in authentication-related endpoints.
• Alert on requests where the user_id parameter differs from the session user ID without proper authorization.
• Log all authentication and authorization failures.

Defense:

• Implement strict server-side validation of user identity parameters.
• Use session-based user identification (e.g., $_SESSION['user_id']) instead of relying on client-supplied parameters.
• Apply the principle of least privilege: users should only be able to access their own data unless explicitly authorized (e.g., admin).
• Implement multi-factor authentication (MFA) to reduce the impact of credential compromise.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests with modified user_id parameters that do not match the session user.
  • Repeated 403 Forbidden responses followed by successful 200 OK responses for the same endpoint.
• Logs:
  • Authentication logs showing a user accessing another user's profile or data.
  • Error logs with messages like "User ID mismatch" or "Unauthorized access attempt".
• System:
  • Unusual account activity (e.g., a low-privileged user accessing admin functions).
  • Creation of new users or modification of user roles by unauthorized accounts.

Detection Engineering

YARA Rule

rule Detect_WebITR_AuthBypass_Attempt {
    meta:
        description = "Detects attempts to exploit CVE-2025-13768 in WebITR logs"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-13768"
    strings:
        $s1 = "user_id=" nocase
        $s2 = "uid=" nocase
        $s3 = "username=" nocase
        $s4 = "HTTP/1.1 200" nocase
        $s5 = "HTTP/1.1 403" nocase
    condition:
        any of ($s1, $s2, $s3) and ($s4 or $s5)
}

Sigma Rule

title: WebITR Authentication Bypass Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2025-13768 in WebITR
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains:
            - 'user_id='
            - 'uid='
            - 'username='
    condition: selection
falsepositives:
    - Legitimate user profile updates
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-13768 WebITR Authentication Bypass Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"user_id="; http_client_body;
    sid:1000001;
    rev:1;
    reference:cve,2025-13768;
    classtype:attempted-user;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the WebITR application from the internet if possible.
2. Implement a Web Application Firewall (WAF) rule to block requests with modified user_id parameters that do not match the session user.
3. Enforce strict session management: ensure the user identity is derived from the server-side session, not from client-supplied parameters.

Long-Term Fix:

• Contact Uniong for an official patch.
• If no patch is available, consider migrating to a different, actively maintained application.
• Conduct a full security audit of the application to identify similar vulnerabilities.

Compensating Controls:

• Enable detailed logging and monitoring for all authentication-related events.
• Implement multi-factor authentication (MFA) to reduce the impact of credential theft.
• Apply the principle of least privilege to all user accounts.

Valters IT