National CSIRT-CY | National Computer Security Incident Response Team of Cyprus

Η Εθνική Ομάδα Αντιμετώπισης Ηλεκτρονικών Επιθέσεων προβλέπει την αύξηση της ηλεκτρονικής ασφαλείας ενισχύοντας την προστασία του κυβερνοχώρου των Εθνικών Κρίσιμων Πληροφοριακών Υποδομών, των τραπεζών και των παροχών επικοινωνίας της Κυπριακής Δημοκρατίας.

Critical WordPress plugin bug lets hackers take over 1M sites

08 Μαΐου 2020

Hackers are actively exploiting two security vulnerabilities in the Elementor Pro and Ultimate Addons for Elementor WordPress plugins with the end goal of remotely executing arbitrary code and fully compromising unpatched targets.

Reports of threat actors attempting to abuse the two bugs in ongoing attacks have surfaced on May 6th as reported by Wordfence’s Threat Intelligence team today.

Attackers can wipe sites after successful exploitation

Elementor Pro is a paid plugin with an estimated number of over 1 million active installations that helps users to easily create WordPress websites from scratch with the help of a built-in theme builder, visual form widget designer, and custom CSS support.

The Elementor Pro vulnerability is a remote code execution bug rated as Critical that allows attackers with registered user access to upload arbitrary files on the targeted websites and execute code remotely — when the attacks started this was a zero-day.

The attackers who successfully exploit this security flaw can then install backdoors or webshells to maintain access to the compromised sites, gain full admin access to fully compromise it, or even wipe the entire site.

If they can’t register as users, they can exploit the second vulnerability affecting the Ultimate Addons for Elementor WordPress plugin (installed on over 110,000 sites) which will allow them to register as subscriber-level users on any site running the plugin even if user registration is disabled.

“Then they proceed to use the newly registered accounts to exploit the Elementor Pro [..] vulnerability and achieve remote code execution,” as Wordfence discovered.

Mitigation measures

To defend against these ongoing attacks you need to update Elementor Pro to version 2.9.4 which fixes the remote code execution vulnerability.

Users of the Ultimate Addons for Elementor will have to upgrade it to version 1.24.2 or later.

Wordfence recommends taking the following measures to make sure that your site hasn’t already been compromised:

• Check for any unknown subscriber-level users on your site. This may indicate that your site has been compromised as a part of this active campaign. If so, remove those accounts.
• Check for files named “wp-xmlrpc.php.” These can be considered an indication of compromise, so check your site for evidence of this file.
• Delete any unknown files or folders found in /wp-content/uploads/elementor/custom-icons/ directory. Files located here after a rogue subscriber-level account has been created are a clear indication of compromise.

Another massive series of attacks targeting more than 900,000 WordPress sites has started on April 28, attempting to redirect visitors to malvertising sites or to plant backdoors if their administrators are logged in.

The threat actor behind them used at least 24,000 IP‌ addresses to send malicious requests to over 900,000 sites, with more than 20 million attacks having been launched against over half a million sites on May 3rd alone.

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