PSA: Nearly 5 Million Attacks Blocked Targeting 0-Day in BackupBuddy Plugin

Late evening, on September 6, 2022, the Wordfence Threat Intelligence team was alerted to the presence of a vulnerability being actively exploited in BackupBuddy, a WordPress plugin we estimate has around 140,000 active installations. This vulnerability makes it possible for unauthenticated users to download arbitrary files from the affected site which can include sensitive information.

After reviewing historical data, we determined that attackers started targeting this vulnerability on August 26, 2022, and that we have blocked 4,948,926 attacks targeting this vulnerability since that time.

The vulnerability affects versions 8.5.8.0 to 8.7.4.1, and has been fully patched as of September 2, 2022 in version 8.7.5. Due to the fact that this is an actively exploited vulnerability, we strongly encourage you to ensure your site has been updated to the latest patched version 8.7.5 which iThemes has made available to all site owners running a vulnerable version regardless of licensing status.

All Wordfence customers, including Wordfence Premium, Wordfence Care, Wordfence Response, and Wordfence Free users, have been, and will continue to be, protected against any attackers trying to exploit this vulnerability due to the Wordfence firewall’s built-in directory traversal and file inclusion firewall rules. Wordfence Premium, Care, & Response, customers receive enhanced protection as attackers heavily targeting the vulnerability are blocked by the IP Blocklist.

Vulnerability Details

The BackupBuddy plugin for WordPress is designed to make back-up management easy for WordPress site owners. One of the features in the plugin is to store back-up files in multiple different locations, known as Destinations, which includes Google Drive, OneDrive, and AWS just to name a few. There is also the ability to store back-up downloads locally via the ‘Local Directory Copy’ option. Unfortunately, the method to download these locally stored files was insecurely implemented making it possible for unauthenticated users to download any file stored on the server.

More specifically the plugin registers an admin_init hook for the function intended to download local back-up files and the function itself did not have any capability checks nor any nonce validation. This means that the function could be triggered via any administrative page, including those that can be called without authentication (admin-post.php), making it possible for unauthenticated users to call the function. The back-up path is not validated and therefore an arbitrary file could be supplied and subsequently downloaded.

Due to this vulnerability being actively exploited, and its ease of exploitation, we are sharing minimal details about this vulnerability.

Indicators of Compromise

The Wordfence firewall has blocked over 4.9 million exploit attempts targeting this vulnerability since August 26, 2022, which is the first indication we have that this vulnerability was being exploited. We are seeing attackers attempting to retrieve sensitive files such as the /wp-config.php and /etc/passwd file which can be used to further compromise a victim.

The top 10 Attacking IP Addresses are as follows:

• 195.178.120.89 with 1,960,065 attacks blocked
• 51.142.90.255 with 482,604 attacks blocked
• 51.142.185.212 with 366770 attacks blocked
• 52.229.102.181 with 344604 attacks blocked
• 20.10.168.93 with 341,309 attacks blocked
• 20.91.192.253 with 320,187 attacks blocked
• 23.100.57.101 with 303,844 attacks blocked
• 20.38.8.68 with 302,136 attacks blocked
• 20.229.10.195 with 277,545 attacks blocked
• 20.108.248.76 with 211,924 attacks blocked

A majority of the attacks we have observed are attempting to read the following files:

• /etc/passwd
• /wp-config.php
• .my.cnf
• .accesshash

We recommend checking for the ‘local-download’ and/or the ‘local-destination-id’ parameter value when reviewing requests in your access logs. Presence of these parameters along with a full path to a file or the presence of ../../ to a file indicates the site may have been targeted for exploitation by this vulnerability. If the site is compromised, this can suggest that the BackupBuddy plugin was likely the source of compromise.

Conclusion

In today’s post, we detailed a zero-day vulnerability being actively exploited in the BackupBuddy plugin that makes it possible for unauthenticated attackers to steal sensitive files from an affected site and use the information obtained in those files to further infect a victim. This vulnerability was patched yesterday and we strongly recommend updating to the latest version of the plugin, currently version 8.7.5, right now since this is an actively exploited vulnerability.

All Wordfence customers, including Wordfence Premium, Wordfence Care, Wordfence Response, and Wordfence Free users, have been, and will continue to be, protected against any attackers trying to exploit this vulnerability due to the Wordfence firewall’s built-in directory traversal and file inclusion firewall rules.

If you believe your site has been compromised as a result of this vulnerability or any other vulnerability, we offer Incident Response services via Wordfence Care. If you need your site cleaned immediately, Wordfence Response offers the same service with 24/7/365 availability and a 1-hour response time. Both these products include hands-on support in case you need further assistance.

If you know a friend or colleague who is using this plugin on their site, we highly recommend forwarding this advisory to them to help keep their sites protected, as this is a serious vulnerability that is actively being exploited in the wild.

We will continue to monitor the situation and follow up as more information becomes available.