CVE-2025-51656

Executive Summary

CVE-2025-51656 identifies a SQL injection vulnerability in SemCms v5.0, specifically within the SEMCMS_Link.php file via the ID parameter. This flaw allows an unauthenticated attacker to inject arbitrary SQL commands, potentially leading to unauthorized data access, modification, or deletion. The vulnerability is publicly known, but no official patch or exploit code has been released. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant due to the potential impact on data confidentiality and integrity.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder. Based on the vulnerability type (SQL injection) and the lack of authentication requirements, a realistic CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Full database read access possible.
• Integrity (I): High (H) – Data can be modified or deleted.
• Availability (A): High (H) – Database can be disrupted or destroyed.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Estimated Base Score: 9.8 (Critical)

Deep Dive & Mechanics

The vulnerability resides in the SEMCMS_Link.php file of SemCms v5.0. The ID parameter is directly concatenated into a SQL query without proper sanitization or parameterization. An attacker can manipulate this parameter to break out of the intended SQL syntax and execute arbitrary commands.

Vulnerable Code Snippet (Conceptual):

$id = $_GET['ID'];
$query = "SELECT * FROM links WHERE id = $id";
$result = mysqli_query($conn, $query);

Attack Vector: An attacker sends a crafted HTTP GET request to SEMCMS_Link.php with a malicious ID parameter. For example:

GET /SEMCMS_Link.php?ID=1 UNION SELECT 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100 HTTP/1.1
Host: target.com

This would attempt to union the results with a crafted set of columns, potentially revealing database structure or sensitive data.

Vulnerable vs. Patched Code

Vulnerable Code (SemCms v5.0):

$id = $_GET['ID'];
$query = "SELECT * FROM links WHERE id = $id";
$result = mysqli_query($conn, $query);

Patched Code (Hypothetical):

$id = intval($_GET['ID']);
$query = "SELECT * FROM links WHERE id = $id";
$result = mysqli_query($conn, $query);

Or using prepared statements:

$stmt = $conn->prepare("SELECT * FROM links WHERE id = ?");
$stmt->bind_param("i", $id);
$stmt->execute();
$result = $stmt->get_result();

The patched version ensures the ID parameter is treated as an integer, preventing SQL injection. Prepared statements are the most robust solution.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Deploy a vulnerable SemCms v5.0 instance (e.g., using Docker or a local web server with PHP and MySQL).
2. Ensure the SEMCMS_Link.php file is accessible.

Exploitation Steps:

1. Reconnaissance: Identify the number of columns in the links table using ORDER BY:

   GET /SEMCMS_Link.php?ID=1 ORDER BY 10--
   

   Increment the number until an error occurs.
2. Extract Data: Use UNION SELECT to retrieve database information:

   GET /SEMCMS_Link.php?ID=1 UNION SELECT 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100--
   

3. Blind SQL Injection: If no output is visible, use time-based or boolean-based techniques:

   GET /SEMCMS_Link.php?ID=1 AND SLEEP(5)--
   

No exploit code was provided in the Hacker Arsenal.

Blue Team (Defensive)

Detection:

• Monitor web server logs for suspicious GET requests to SEMCMS_Link.php containing SQL keywords like UNION, SELECT, SLEEP, OR, AND, --, #, or /*.
• Look for abnormal patterns in the ID parameter, such as long strings, special characters, or encoded payloads.

Mitigation:

• Immediately apply input validation and parameterized queries.
• Use a Web Application Firewall (WAF) to block SQL injection patterns.
• Restrict database user permissions to the minimum required.

Indicators of Compromise (IOCs)

• Network:

  • HTTP GET requests to /SEMCMS_Link.php with ID parameter containing SQL keywords.
  • Unusual response times (time-based injection).
  • Database error messages in HTTP responses.

• Host:

  • Unexpected database queries in MySQL logs.
  • Modified or deleted records in the links table.
  • Presence of new database users or privileges.

• File:

  • Suspicious entries in web server access logs (e.g., 192.168.1.100 - - [10/Jan/2025:12:00:00 +0000] "GET /SEMCMS_Link.php?ID=1 UNION SELECT ... HTTP/1.1" 200).

Detection Engineering

YARA Rule

rule CVE_2025_51656_SQLi_SemCms {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2025-51656 in SemCms v5.0"
        author = "Valters IT"
        date = "2025-01-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-51656"
    strings:
        $s1 = "SEMCMS_Link.php" nocase
        $s2 = "ID=" nocase
        $s3 = "UNION" nocase
        $s4 = "SELECT" nocase
        $s5 = "SLEEP" nocase
        $s6 = "OR" nocase
        $s7 = "AND" nocase
        $s8 = "--" nocase
        $s9 = "#" nocase
        $s10 = "/*" nocase
    condition:
        $s1 and $s2 and any of ($s3, $s4, $s5, $s6, $s7, $s8, $s9, $s10)
}

Sigma Rule

title: SQL Injection Attempt Against SemCms SEMCMS_Link.php
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects SQL injection attempts targeting CVE-2025-51656 in SemCms v5.0
author: Valters IT
date: 2025-01-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - "SEMCMS_Link.php"
            - "ID="
        cs-uri-query|contains|all:
            - "UNION"
            - "SELECT"
    condition: selection
falsepositives:
    - Legitimate use of UNION SELECT in rare cases
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-51656 SQL Injection Attempt - SemCms SEMCMS_Link.php"; flow:to_server,established; content:"GET"; http_method; content:"SEMCMS_Link.php"; http_uri; content:"ID="; http_uri; pcre:"/(UNION|SELECT|SLEEP|OR|AND|--|#|\/\*)/Ui"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action:

   • Disable or remove SEMCMS_Link.php if not essential.
   • Apply input validation: cast ID to integer.
   • Use prepared statements for all database queries.

2. Long-term Fix:

   • Upgrade to a patched version of SemCms (if available).
   • Conduct a full security audit of the application.
   • Implement a Web Application Firewall (WAF) with SQL injection rules.

3. Monitoring:

   • Enable detailed logging for all web requests.
   • Set up alerts for SQL injection patterns.
   • Regularly review database logs for unauthorized queries.

4. User Awareness:

   • Educate developers on secure coding practices (OWASP Top 10).
   • Enforce least privilege for database accounts.

Valters IT
Securing Digital Frontiers