CVE-2025-47587

Executive Summary

CVE-2025-47587 is a critical Blind SQL Injection vulnerability discovered in the YaySMTP plugin by YayCommerce, a WordPress plugin ecosystem component. The flaw resides in improper neutralization of special elements used in an SQL command, allowing an unauthenticated attacker to perform blind SQL injection attacks. This vulnerability affects all versions of YaySMTP up to and including 2.6.4. With a CVSS score of 7.6, the vulnerability poses a significant risk to confidentiality, integrity, and availability of the underlying WordPress database. No public proof-of-concept (PoC) or exploit code has been released at this time, and the patch status remains unknown.

Supply Chain & Package Security

YaySMTP is distributed as a WordPress plugin, typically installed via the WordPress plugin repository or directly uploaded to a WordPress instance. The supply chain risk is elevated because the plugin is widely used for email delivery, and a compromised plugin could lead to data exfiltration of email logs, user credentials, and other sensitive database contents. Organizations should verify the integrity of their plugin files and monitor for any unauthorized modifications.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability can be exploited remotely over the network.
• Attack Complexity (AC): Low (L) – No special conditions or complex attack sequences are required.
• Privileges Required (PR): None (N) – No authentication is needed to exploit the vulnerability.
• User Interaction (UI): None (N) – The victim does not need to perform any action.
• Scope (S): Unchanged (U) – The exploitation does not affect other components beyond the vulnerable plugin.
• Confidentiality (C): High (H) – Successful exploitation can lead to full database disclosure.
• Integrity (I): Low (L) – Limited ability to modify database content.
• Availability (A): Low (L) – Potential for denial of service through resource exhaustion.

Threat Level: High. The combination of network-based, unauthenticated access with high confidentiality impact makes this a critical threat for any WordPress site using the YaySMTP plugin.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection flaw where user-supplied input is not properly sanitized before being used in SQL queries. In YaySMTP, the plugin likely processes parameters such as search filters, pagination, or AJAX requests without adequate escaping. An attacker can inject malicious SQL payloads into these parameters, causing the database to execute unintended commands.

Because this is a blind SQL injection, the attacker does not receive direct error messages or data output. Instead, they infer information by observing differences in response times or boolean responses (e.g., true/false conditions). This technique allows an attacker to extract data character by character, such as usernames, password hashes, and other sensitive information stored in the WordPress database.

The vulnerable code likely resides in a function that constructs SQL queries using string concatenation with user input. For example:

$query = "SELECT * FROM wp_options WHERE option_name = '" . $_GET['option'] . "'";

Without proper escaping, an attacker can break out of the string context and inject SQL commands.

Vulnerable vs. Patched Code

Vulnerable Code (Example):

function yaysmtp_search_logs($search_term) {
    global $wpdb;
    $query = "SELECT * FROM {$wpdb->prefix}yaysmtp_logs WHERE subject LIKE '%" . $search_term . "%'";
    $results = $wpdb->get_results($query);
    return $results;
}

Patched Code (Example):

function yaysmtp_search_logs($search_term) {
    global $wpdb;
    $query = $wpdb->prepare(
        "SELECT * FROM {$wpdb->prefix}yaysmtp_logs WHERE subject LIKE %s",
        '%' . $wpdb->esc_like($search_term) . '%'
    );
    $results = $wpdb->get_results($query);
    return $results;
}

The patched version uses $wpdb->prepare() with placeholders and esc_like() to safely handle user input, preventing SQL injection.

Exploitation & Lab Setup

Red Team

Lab Environment:

• WordPress 6.x with YaySMTP 2.6.4 installed and activated.
• MySQL/MariaDB database.
• Attacker machine with Burp Suite or SQLMap.

Exploitation Steps:

1. Identify a vulnerable parameter, e.g., ?s= in the admin AJAX handler.
2. Use SQLMap to automate blind SQL injection:

   sqlmap -u "http://target/wp-admin/admin-ajax.php?action=yaysmtp_search&s=test" --batch --dbs
   

3. Manually confirm with time-based payload:

   test' AND SLEEP(5)--
   

4. Extract data using boolean-based inference:

   test' AND (SELECT SUBSTRING(user_pass,1,1) FROM wp_users WHERE ID=1)='a'--
   

Note: No public exploit code is available; the above is a generic approach.

Blue Team

Detection Steps:

• Monitor for unusual SQL query patterns in database logs.
• Look for HTTP requests containing SQL keywords (e.g., SLEEP, UNION, SELECT) in parameters.
• Implement Web Application Firewall (WAF) rules to block SQL injection patterns.
• Use the detection rules provided in the Detection Engineering section.

Honeypot Setup:

• Deploy a decoy WordPress instance with YaySMTP to capture attacker behavior.
• Log all AJAX requests and analyze for SQL injection attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-admin/admin-ajax.php with parameters containing SQL keywords.
  • Unusual response times (e.g., >5 seconds) indicating time-based injection.
• File IOCs:
  • Modified plugin files in /wp-content/plugins/yaysmtp/.
  • Suspicious entries in WordPress debug log (wp-content/debug.log).
• Database IOCs:
  • Unexpected entries in wp_options or wp_usermeta tables.
  • Queries with SLEEP() or BENCHMARK() functions in MySQL logs.

Detection Engineering

YARA Rule

rule CVE_2025_47587_YaySMTP_SQLi {
    meta:
        description = "Detects SQL injection attempts targeting YaySMTP plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-47587"
    strings:
        $sqli1 = "SLEEP(" ascii nocase
        $sqli2 = "UNION SELECT" ascii nocase
        $sqli3 = "OR 1=1" ascii nocase
        $sqli4 = "admin-ajax.php" ascii nocase
        $sqli5 = "yaysmtp" ascii nocase
    condition:
        all of ($sqli*) and filesize < 10KB
}

Sigma Rule

title: CVE-2025-47587 YaySMTP SQL Injection Attempt
id: 8a9b3c2d-1e5f-4a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects SQL injection attempts against YaySMTP plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'SLEEP('
            - 'UNION SELECT'
            - 'OR 1=1'
            - 'admin-ajax.php'
            - 'yaysmtp'
    condition: selection
falsepositives:
    - Legitimate use of similar strings in non-malicious contexts
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-47587 YaySMTP SQL Injection Attempt"; flow:to_server,established; content:"admin-ajax.php"; http_uri; content:"yaysmtp"; http_uri; pcre:"/(SLEEP\(|UNION\s+SELECT|OR\s+1=1)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Implement a Web Application Firewall (WAF) with rules to block SQL injection patterns.
3. Restrict access to /wp-admin/admin-ajax.php using IP whitelisting or authentication.

Long-term Fix:

• Apply the official patch from YayCommerce as soon as it is released.
• Update to the latest version of YaySMTP (if a patched version becomes available).
• Conduct a security audit of all WordPress plugins and themes.

Workarounds:

• Use a security plugin like Wordfence to add virtual patching.
• Manually sanitize input by modifying the plugin code (not recommended for non-developers).

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.