CVE-2024-11135

Executive Summary

CVE-2024-11135 is a critical unauthenticated SQL Injection vulnerability discovered in the Eventer WordPress plugin, affecting all versions up to and including 3.9.8. The flaw resides in the eventer_get_attendees function, where the event parameter is insufficiently sanitized and not properly prepared for SQL queries. This allows unauthenticated attackers to inject arbitrary SQL commands, potentially extracting sensitive data from the WordPress database, such as user credentials, session tokens, and other confidential information. The vulnerability has a CVSS score of 7.5 (High) and is currently unpatched, posing a significant risk to all sites using the affected plugin.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The Eventer plugin is distributed through the official WordPress plugin repository and third-party marketplaces. Since no official patch has been released, the supply chain risk is elevated. Site administrators must treat this as a zero-day threat and consider removing or disabling the plugin until a fix is available. No known open-source patches or GitHub advisories exist at this time.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

The vulnerability allows unauthenticated remote attackers to extract sensitive information from the database without any user interaction. The high confidentiality impact makes this a critical threat for data breaches.

Deep Dive & Mechanics

The vulnerability exists in the eventer_get_attendees function, which is typically called via AJAX or REST endpoints. The event parameter is directly concatenated into an SQL query without proper escaping or parameterized preparation. An attacker can inject SQL commands by crafting a malicious event value.

Root Cause:

• Insufficient input sanitization on the event parameter.
• Lack of prepared statements or parameterized queries in the eventer_get_attendees function.

Attack Flow:

1. An unauthenticated attacker sends a crafted HTTP request to the vulnerable endpoint.
2. The event parameter is passed directly into the SQL query.
3. The injected SQL executes, allowing the attacker to extract data from the database.

Example vulnerable SQL query (pseudocode):

SELECT * FROM wp_eventer_attendees WHERE event_id = '{$_GET['event']}'

An attacker could inject:

1' UNION SELECT user_login, user_pass FROM wp_users --

Vulnerable vs. Patched Code

Since no official patch is available, the following shows the vulnerable code pattern and a recommended fix.

Vulnerable Code (eventer.php or similar):

function eventer_get_attendees() {
    global $wpdb;
    $event_id = $_GET['event'];
    $results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}eventer_attendees WHERE event_id = '$event_id'");
    return $results;
}

Patched Code (recommended):

function eventer_get_attendees() {
    global $wpdb;
    $event_id = intval($_GET['event']); // Cast to integer
    $results = $wpdb->get_results($wpdb->prepare("SELECT * FROM {$wpdb->prefix}eventer_attendees WHERE event_id = %d", $event_id));
    return $results;
}

The patched version uses intval() to ensure the input is an integer and $wpdb->prepare() to parameterize the query, preventing SQL injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Eventer plugin version <= 3.9.8.
• The vulnerable endpoint is typically /wp-admin/admin-ajax.php?action=eventer_get_attendees&event=INJECTION.

Exploit Steps:

1. Identify the vulnerable endpoint.
2. Craft a payload to extract data.

Proof-of-Concept (PoC) using curl:

curl -X GET "http://target.com/wp-admin/admin-ajax.php?action=eventer_get_attendees&event=1' UNION SELECT user_login,user_pass,user_email FROM wp_users-- -"

Expected Output: The response will contain the extracted user credentials (hashed passwords) from the wp_users table.

Advanced Exploitation:

• Use time-based blind SQL injection to extract data when UNION is blocked.
• Use LOAD_FILE() to read server files if the database user has FILE privileges.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual SQL error messages in logs.
• Look for requests to admin-ajax.php with action=eventer_get_attendees and suspicious event parameters containing SQL keywords (UNION, SELECT, etc.).

Defense:

• Immediately disable or remove the Eventer plugin.
• Implement a Web Application Firewall (WAF) rule to block SQL injection patterns.
• Apply virtual patching via WAF or reverse proxy.

WAF Rule Example (ModSecurity):

SecRule ARGS:event "@rx (union|select|insert|drop|--)" "id:1001,phase:2,deny,status:403,msg:'SQL Injection Attempt Blocked'"

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /wp-admin/admin-ajax.php with action=eventer_get_attendees and event parameter containing SQL keywords.
  • Unusual SQL error messages in server logs (e.g., "You have an error in your SQL syntax").

• File IOCs:

  • Modified or new files in /wp-content/plugins/eventer/ (if attacker uploads webshells).
  • Suspicious entries in WordPress wp_options table (e.g., malicious admin users).

• Database IOCs:

  • Unauthorized queries to wp_users, wp_usermeta, or other sensitive tables.
  • New user accounts with administrative privileges.

Detection Engineering

YARA Rule

rule CVE_2024_11135_Eventer_SQLi {
    meta:
        description = "Detects SQL injection attempts targeting Eventer plugin CVE-2024-11135"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-11135"
    strings:
        $sqli1 = "union select" nocase
        $sqli2 = "union all select" nocase
        $sqli3 = "information_schema" nocase
        $sqli4 = "wp_users" nocase
        $sqli5 = "admin-ajax.php" nocase
        $sqli6 = "eventer_get_attendees" nocase
    condition:
        all of ($sqli5, $sqli6) and 1 of ($sqli1, $sqli2, $sqli3, $sqli4)
}

Sigma Rule

title: CVE-2024-11135 Eventer SQL Injection Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SQL injection attempts against the Eventer WordPress plugin
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-11135
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-query|contains:
            - "action=eventer_get_attendees"
            - "event="
    keywords:
        - "union"
        - "select"
        - "information_schema"
        - "wp_users"
    condition: selection and keywords
falsepositives:
    - Legitimate use of the word "union" in event names (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-11135 Eventer SQL Injection Attempt"; flow:to_server,established; content:"admin-ajax.php"; http_uri; content:"action=eventer_get_attendees"; http_uri; content:"event="; http_uri; pcre:"/(union|select|information_schema|wp_users)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Eventer plugin until an official patch is released.
2. Implement virtual patching via WAF to block SQL injection patterns.
3. Review server logs for signs of exploitation (unusual SQL errors, suspicious requests).

Long-term Fix:

• The vendor must release a patched version that uses prepared statements and input validation.
• If no patch is forthcoming, consider migrating to an alternative event management plugin.

Compromise Assessment:

• Check for unauthorized database queries or data exfiltration.
• Audit user accounts for unauthorized administrative access.
• Scan for webshells or backdoors in the WordPress installation.

Valters IT
Securing Digital Frontiers