Vulnerability Summary from Wordfence Intelligence
Description: Backup Migration <= 1.3.7 backup-backup Unauthenticated Remote Code Execution 
Affected Plugin: Backup Migration
Plugin Slug: backup-backup
Affected Versions: <= 1.3.7
CVE ID:CVE-2023-6553
Pending CVSS Score: 9.8 (Critical)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Researcher/s: Nex Team 
Fully Patched Version: 1.3.8
Bounty Award: $2,751.00
The Backup Migration plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 1.3.7 via the /includes/backup-heart.php file. This is due to an attacker being able to control the values passed to an include, and subsequently leverage that to achieve remote code execution. This makes it possible for unauthenticated threat actors to easily execute code on the server.
Technical Analysis
Line 118 within the /includes/backup-heart.php file used by the Backup Migration plugin attempts to include bypasser.php from the BMI_INCLUDES directory. The BMI_INCLUDES directory is defined by concatenating BMI_ROOT_DIR with the includes string on line 64. However, note that BMI_ROOT_DIR is defined via the content-dir HTTP header on line 62.
affected_code_image_2 
This means that the BMI_ROOT_DIR is user-controllable. By submitting a specially-crafted request, threat-actors can leverage this issue to include arbitrary, malicious PHP code and execute arbitrary commands on the underlying server in the security context of the WordPress instance.
Disclosure Timeline
December 5, 2023 – We receive the submission of the PHP Code Injection vulnerability in Backup Migration via the Wordfence Bug Bounty Program.
December 6, 2023 – We validate the report and confirm the proof-of-concept exploit.
December 6, 2023 – We initiate contact with the plugin developer and send over the full disclosure details. The vendor acknowledges the report and begins working on a fix. A fully patched version of the plugin, 1.3.8, is released.
Conclusion
In this blog post, we detailed a critical PHP Code Injection vulnerability within the Backup Migration plugin affecting versions 1.3.7 and earlier. This vulnerability allows unauthenticated threat actors to inject arbitrary PHP code, resulting in a full site compromise. The vulnerability has been fully addressed in version 1.3.8 of the plugin.
We urge WordPress users to verify that their sites are updated to the latest patched version of Backup Migration.
Wordfence users running Wordfence Premium , Wordfence Care , and Wordfence Response  have been protected against these vulnerabilities as of December 6, 2023. Users still using the free version of Wordfence will receive the same protection on January 5, 2024.
If you know someone who uses this plugin on their site, we recommend sharing this advisory with them to ensure their site remains secure, as this vulnerability poses a significant risk.