CVE-2019-25506: FreeSMS SQL Injection Vulnerability

CVE-2019-25506 Overview

FreeSMS 2.1.2 contains a boolean-based blind SQL injection vulnerability in the password parameter that allows unauthenticated attackers to bypass authentication by injecting SQL code through the login endpoint. Attackers can exploit the vulnerable password parameter in requests to /pages/crc_handler.php?method=login to authenticate as any known user and subsequently modify their password via the profile update function.

Critical Impact

This SQL injection vulnerability enables complete authentication bypass, allowing attackers to gain unauthorized access to any user account and potentially take over the entire FreeSMS application.

Affected Products

• FreeSMS 2.1.2

Discovery Timeline

• 2026-03-04 - CVE CVE-2019-25506 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2019-25506

Vulnerability Analysis

This vulnerability is classified as CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection'). The flaw exists in FreeSMS 2.1.2's login authentication mechanism, specifically within the password parameter handling at the /pages/crc_handler.php?method=login endpoint.

The application fails to properly sanitize user-supplied input before incorporating it into SQL queries. This allows attackers to inject malicious SQL code through the password field during authentication attempts. Because the injection point is in the authentication logic, successful exploitation grants attackers the ability to bypass login controls entirely without knowing valid credentials.

The boolean-based blind nature of this SQL injection means the attacker cannot directly view database query results. Instead, they infer information by observing differences in the application's behavior based on whether injected conditions evaluate to true or false. Despite this limitation, the attack is highly effective for authentication bypass scenarios.

Root Cause

The root cause of this vulnerability is insufficient input validation and improper parameterization of SQL queries in the authentication handler. The password parameter is directly concatenated into SQL statements without sanitization or the use of prepared statements with parameterized queries. This allows specially crafted input to alter the intended query logic, enabling attackers to manipulate authentication checks.

Attack Vector

The attack is executed over the network without requiring any prior authentication or user interaction. An attacker sends a crafted HTTP request to the login endpoint with a malicious SQL payload in the password parameter.

The exploitation flow typically involves:

1. Identifying the vulnerable login endpoint at /pages/crc_handler.php?method=login
2. Crafting a boolean-based SQL injection payload in the password parameter
3. Using the payload to manipulate the authentication query to return true for any targeted username
4. Successfully authenticating as the targeted user without knowing their actual password
5. Optionally using the profile update functionality to change the compromised user's password for persistent access

For detailed technical information and proof-of-concept examples, see the Exploit-DB #46658 entry and the VulnCheck Advisory.

Detection Methods for CVE-2019-25506

Indicators of Compromise

• Unusual login activity for user accounts, particularly successful authentications from unexpected IP addresses or at unusual times
• HTTP requests to /pages/crc_handler.php?method=login containing SQL syntax characters such as single quotes, double dashes, OR, AND, or UNION keywords in POST data
• Multiple rapid authentication attempts followed by a successful login, indicating potential injection testing
• Unexpected password changes in user accounts that the legitimate users did not initiate

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common SQL injection patterns in login request parameters
• Deploy application-layer logging to capture full request bodies for authentication endpoints, enabling forensic analysis
• Configure intrusion detection systems (IDS) to alert on requests containing SQL injection signatures targeting the FreeSMS login endpoint
• Monitor authentication logs for anomalous patterns such as successful logins from new geographic locations or devices

Monitoring Recommendations

• Enable detailed access logging for the /pages/crc_handler.php endpoint and review logs regularly for suspicious patterns
• Set up alerts for failed login attempts followed by successful authentication from the same source IP
• Monitor database query logs for malformed or suspicious SQL statements originating from the web application
• Track user account modifications, particularly password changes, and correlate with recent login activity

How to Mitigate CVE-2019-25506

Immediate Actions Required

• If FreeSMS 2.1.2 is deployed in production, consider taking the application offline until the vulnerability can be addressed
• Implement network-level access controls to restrict access to the FreeSMS login endpoint to trusted networks only
• Deploy a Web Application Firewall with SQL injection protection rules in front of the FreeSMS application
• Audit user accounts for unauthorized access or unexpected password changes and force password resets for any potentially compromised accounts

Patch Information

No official vendor patch has been identified in the available CVE data. Organizations using FreeSMS 2.1.2 should contact the vendor directly to inquire about security updates or consider migrating to an alternative SMS gateway solution with active security maintenance.

For additional context, review the VulnCheck Advisory for the latest information on this vulnerability.

Workarounds

• Place the FreeSMS application behind a reverse proxy or WAF configured to filter SQL injection attempts in authentication requests
• Restrict network access to the FreeSMS login endpoint using firewall rules, limiting access to trusted IP ranges only
• If source code modifications are possible, implement prepared statements with parameterized queries for all database operations in the authentication handler
• Consider disabling the vulnerable application entirely if it is not business-critical until a proper fix is available
• Monitor for and respond to any signs of exploitation while mitigations are in place

# Example WAF rule concept for blocking SQL injection in login requests
# This is a conceptual example - adjust for your specific WAF solution

# Block requests containing common SQL injection patterns in POST body
# targeting the FreeSMS login endpoint
location /pages/crc_handler.php {
    # Deny requests with SQL injection patterns
    if ($request_body ~* "(union|select|insert|update|delete|drop|--|;|'|\")") {
        return 403;
    }
}