CVE-2024-47926

Executive Summary

CVE-2024-47926 is a critical SQL Injection vulnerability in Tecnick TCExam, a web-based exam management system. The flaw resides in improper neutralization of special elements used in an SQL command, allowing an unauthenticated remote attacker to execute arbitrary SQL queries against the backend database. With a CVSS score of 9.8, this vulnerability poses a severe risk to data confidentiality, integrity, and availability. No public proof-of-concept (PoC) or exploit code has been released, and no official patch is currently available. The EPSS score of 0.0% indicates low exploitation activity in the wild, but the criticality demands immediate attention.

Supply Chain & Package Security

This vulnerability affects a standalone PHP application (TCExam) and is not distributed via NPM, PyPI, Go, or Ruby package managers. However, organizations using TCExam should treat it as a critical supply chain risk due to the lack of a patch and the potential for data exfiltration.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – Full database read access.
• Integrity Impact: High (I:H) – Ability to modify or delete data.
• Availability Impact: High (A:H) – Potential for denial of service via SQL manipulation.

Threat Level: Critical. Immediate remediation is required.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection (CWE-89) in TCExam. The application fails to sanitize user-supplied input before incorporating it into SQL queries. An attacker can inject malicious SQL code through input fields (e.g., login forms, search parameters, or API endpoints) to manipulate the database.

Attack Flow:

1. The attacker identifies an input parameter that is directly concatenated into an SQL query.
2. The attacker submits a crafted payload (e.g., ' OR '1'='1) to bypass authentication or extract data.
3. The backend executes the malicious SQL, returning unauthorized data or allowing further exploitation.

Potential Impact:

• Full database compromise (user credentials, exam data, system configurations).
• Lateral movement to other systems if database credentials are reused.
• Data exfiltration or ransomware deployment.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical example of the vulnerable code pattern and its secure counterpart.

Vulnerable Code (PHP):

$username = $_POST['username'];
$password = $_POST['password'];
$query = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($conn, $query);

Patched Code (PHP):

$username = mysqli_real_escape_string($conn, $_POST['username']);
$password = mysqli_real_escape_string($conn, $_POST['password']);
$query = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($conn, $query);

Better Approach (Prepared Statements):

$stmt = $conn->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
$result = $stmt->get_result();

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A vulnerable instance of TCExam (version unknown).
• Network access to the application.

Manual Exploitation Steps:

1. Identify an input field (e.g., login form, search box).
2. Inject a test payload: ' OR '1'='1
3. If successful, the application returns data for all users.
4. Use SQLmap for automated exploitation:

   sqlmap -u "http://target.com/login.php" --data="username=admin&password=test" --batch --dbs
   

Example Payloads:

• admin' -- (comment out rest of query)
• ' UNION SELECT 1,2,3,4,5-- (union-based injection)
• ' OR SLEEP(5)-- (time-based blind injection)

Blue Team (Detection & Defense)

Detection:

• Monitor web server logs for SQL injection patterns (e.g., ' OR, UNION, --).
• Deploy a Web Application Firewall (WAF) with SQL injection rules.
• Use the detection rules provided in the Detection Engineering section.

Defense:

• Immediately isolate the TCExam server if possible.
• Apply input validation and parameterized queries as a temporary fix.
• Restrict database user privileges to least privilege.
• Enable detailed logging for forensic analysis.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests containing SQL keywords in parameters (e.g., UNION, SELECT, OR 1=1).
• Unusual database error messages in HTTP responses (e.g., "You have an error in your SQL syntax").

File IOCs:

• Modified PHP files in the TCExam directory (e.g., login.php, admin.php).
• Suspicious files in the web root (e.g., webshells, backdoors).

Log IOCs:

• Repeated failed login attempts followed by successful login.
• Database queries with unexpected syntax in application logs.

Detection Engineering

YARA Rule

rule CVE_2024_47926_SQLi_TCExam {
    meta:
        description = "Detects SQL injection attempts targeting TCExam CVE-2024-47926"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2024-47926"
    strings:
        $sqli1 = /'.*OR.*'1'='1/i
        $sqli2 = /UNION.*SELECT/i
        $sqli3 = /'.*--/i
        $sqli4 = /SLEEP\(/i
    condition:
        any of them
}

Sigma Rule

title: SQL Injection Attempt Against TCExam
id: 8f4a3b2c-1d5e-6f7a-8b9c-0d1e2f3a4b5c
status: experimental
description: Detects SQL injection patterns in HTTP requests to TCExam
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - "' OR"
            - "UNION SELECT"
            - "'--"
            - "SLEEP("
    condition: selection
falsepositives:
    - Legitimate use of SQL keywords in non-malicious contexts (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-47926 TCExam SQL Injection Attempt"; flow:to_server,established; content:"' OR"; http_uri; nocase; content:"'1'='1"; http_uri; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the TCExam server from the network if possible.
2. Apply virtual patching via WAF rules to block SQL injection patterns.
3. Review database logs for signs of compromise.

Long-Term Fixes:

• Upgrade to a patched version once released by Tecnick.
• Rewrite all database queries using prepared statements or parameterized queries.
• Implement strict input validation and output encoding.
• Conduct a full security audit of the application.

Workarounds:

• Disable unused features that accept user input.
• Use a reverse proxy with SQL injection filtering (e.g., ModSecurity).

Valters IT
Securing Digital Frontiers