There has been an increase in attacks targeting a Cross-Site Scripting vulnerability in Beautiful Cookie Consent Banner, a WordPress plugin installed on over 40,000 sites. The vulnerability, which was fully patched in January in version 2.10.2, offers unauthenticated attackers the ability to add malicious JavaScript to a website, potentially allowing redirects to malvertizing sites as well as the creation of malicious admin users, both of which are appealing use cases for attackers.

Description: Beautiful Cookie Consent Banner <= 2.10.1 – Unauthenticated Stored Cross-Site Scripting
Affected Plugin:Beautiful Cookie Consent Banner 
Plugin Slug: beautiful-and-responsive-cookie-consent
Affected Versions: <= 2.10.1
CVE ID: Not Assigned
CVSS Score: 7.2 (High)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Researcher/s: Unknown
Fully Patched Version: 2.10.2

The Beautiful Cookie Consent Banner for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘nsc_bar_content_href’ parameter in versions up to, and including, 2.10.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. A partial patch was made available in 2.10.1 and the issue was fully patched in 2.10.2.

The Attacks

According to our records, the vulnerability has been actively attacked since February 5, 2023, but this is the largest attack against it that we have seen. We have blocked nearly 3 million attacks against more than 1.5 million sites, from nearly 14,000 IP addresses since May 23, 2023, and attacks are ongoing.

We believe that this is the work of a single actor, as every single attack contained a partial payload of onmouseenter=” and no further functioning JavaScript. It is likely that this set of attacks is being performed using a misconfigured exploit that expects a customized payload, and that the attacker has simply failed to provide one.

Despite this fact, if your website is running a vulnerable version of the plugin and you are not currently using Wordfence or another Web Application Firewall, these attacks do have the potential to corrupt the configuration of the plugin which can break its intended functionality, so we still recommend updating to the latest version, which is 2.13.0 at the time of this writing, as soon as possible.

Indicators of Compromise

Requests

POST requests to /wp-admin/admin-post.php from unrecognized IP addresses may appear in your server logs, or in your Live Traffic if you have the Wordfence plugin installed.

IP Addresses

We have included the top 20 attacking IP addresses, though there are many more:

• 209.126.12.142
• 101.34.223.139
• 92.204.37.157
• 66.37.4.138
• 92.205.48.232
• 212.237.233.32
• 195.201.82.166
• 67.205.58.212
• 51.38.27.102
• 173.236.213.148
• 207.244.241.230
• 74.208.177.185
• 92.204.33.117
• 134.119.0.186
• 5.9.238.21
• 92.205.64.149
• 94.158.149.174
• 173.236.215.161
• 92.205.48.177
• 190.54.62.76

If your site was impacted by this or an earlier attack campaign, it may have corrupted the ​​nsc_bar_bannersettings_json option in your database. The plugin’s developers have included functionality in patched versions to repair any changes made as a result of this exploit.

On April 25, 2023, our team identified and began the responsible disclosure process for a stored Cross-Site Scripting (XSS) vulnerability in W3 Eden’s Download Manager plugin, which is actively installed on more than 100,000 WordPress websites, making it one of the most popular download management plugins. The vulnerability enables threat actors with contributor-level permissions or higher to inject malicious web scripts into pages using the plugin’s shortcode.

We contacted W3 Eden on April 25, 2023, and promptly received a response. After providing full disclosure details, the developer released a patch on May 1, 2023. We would like to commend the W3 Eden development team for their prompt response and timely patch.

We urge users to update their sites with the latest patched version of Download Manager, version 3.2.71 at the time of this writing, as soon as possible.

Vulnerability Summary from Wordfence Intelligence

Description: Download Manager <= 3.2.70 – Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode
Affected Plugin: Download Manager
Plugin Slug: download-manager
Affected Versions: <= 3.2.70
CVE ID: CVE-2023-2305
CVSS Score: 6.4 (Medium)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Researcher/s: Lana Codes
Fully Patched Version: 3.2.71

The Download Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘wpdm_members’, ‘wpdm_login_form’, ‘wpdm_reg_form’ shortcodes in versions up to, and including, 3.2.70 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Technical Analysis

Download Manager is a plugin designed to allow WordPress users to manage, track and control file downloads. It provides a shortcode ([wpdm_members]) that lists the authors and the number of files they have added when added to a WordPress page. However, insecure implementation of the plugin’s shortcode functionality allows for the injection of arbitrary web scripts into these pages. Examining the code reveals that the members method in the User class did not adequately sanitize the user-supplied ‘sid’ input, and then loads the members.php view file, where it also did not adequately escape ‘sid’ output. This makes it possible to inject attribute-based Cross-Site Scripting payloads via the ‘sid’ attribute.

There are two other shortcodes, a login form shortcode ([wpdm_login_form]) and a registration form shortcode ([wpdm_reg_form]), that add forms to a WordPress site. However, the insecure implementation of these two shortcode functions, similar to the previous example, also allows arbitrary web scripts to be inserted into these pages. Examining the code reveals that the functions of both forms do not adequately sanitize the user-supplied ‘logo’ input, and in the view files these ‘logo’ outputs are not adequately escaped.

[View the Code Snippets on the Blog] 

These make it possible for threat actors to carry out stored XSS attacks. Once a script is injected into a page or post, it will execute each time a user accesses the affected page. While this vulnerability does require that a trusted contributor account is compromised, or a user be able to register as a contributor, successful threat actors could steal sensitive information, manipulate site content, inject administrative users, edit files, or redirect users to malicious websites which are all severe consequences.

Disclosure Timeline

April 25, 2023 – Wordfence Threat Intelligence team discovers the stored XSS vulnerability in Download Manager and initiates responsible disclosure.
April 27, 2023 – We get in touch with the development team at W3 Eden and send full disclosure details.
May 1, 2023 – The fully patched version, 3.2.71, is released.
May 3, 2023 – The vendor notified Wordfence that they released the patch.
May 3, 2023 – Wordfence confirms the fix addresses the vulnerability.

Conclusion

In this blog post, we have detailed a stored XSS vulnerability within the Download Manager plugin affecting versions 3.2.70 and earlier. This vulnerability allows authenticated threat actors with contributor-level permissions or higher to inject malicious web scripts into pages that execute when a user accesses an affected page. The vulnerability has been fully addressed in version 3.2.71 of the plugin.

We encourage WordPress users to verify that their sites are updated to the latest patched version of Download Manager.