# Exploit Title: Typo3 v4.5-4.7 - Remote Code Execution (RFI/LFI)
# Date: 4th January 2012
# Author: MaXe
# Software Link: https://typo3.org/download/
# Version: 4.5.0 up to 4.5.8, 4.6.0 and 4.6.1 (+ development releases of
4.7 branch)


Typo3 v4.5-4.7 - Remote Code Execution (RFI/LFI)


Versions Affected: 4.5.0 up to 4.5.8, 4.6.0 and 4.6.1 (+ development
releases of 4.7 branch)

Info:
TYPO3 is a small to midsize enterprise-class Content Management Framework
offering
the best of both worlds: out-of-the-box operation with a complete set of
standard
modules and a clean and sturdy high-performance architecture accomodating
virtually
every kind of custom solution or extension.

External Links:
http://typo3.org/

Credits: Björn Pedersen and Christian Toffolo who discovered and reported
the issue and the Security Team member Helmut Hummel for providing the
patch.
(This advisory was rewritten by MaXe @InterN0T to offer a quick overview
of the vulnerability, including the removal of all irrelevant and untrue
details.


-:: The Advisory ::-
Requirements for any RCE:
- register_globals in the php.ini MUST be enabled (if the exploit fails
against a supposed to be vulnerable version, this is why. This setting is
often disabled by default.)

Requirements for RFI:
- allow_url_include has to be enabled (It's often "off" by default.)


Proof of Concept:
By browsing to a script / page, that uses the following file:
typo3/sysext/workspaces/Classes/Controller/AbstractController.php (direct
access may not be allowed)
It is possible to include PHP code to be executed via the "BACK_PATH"
global variable. This can be accessed in ways like:
AbstractController.php?BACK_PATH=LFI/RFI%00

The vulnerable piece of code: require_once($GLOBALS['BACK_PATH'] .
'template.php');
Demonstrates, that it is necessary to append a null-byte ( %00 ) after the
maliciously crafted input / URL. (Unless your remote file if applicable, is
named something.template.php)


-:: Solution ::-
* Update to the latest version of Typo3 OR change the vulnerable piece of
code to: require_once(PATH_site . TYPO3_mainDir . 'template.php');



References:
- http://typo3.org/fileadmin/security-team/bug32571/32571.diff
-
https://typo3.org/teams/security/security-bulletins/typo3-core/typo3-core-sa-2011-004/
-
http://news.typo3.org/news/article/important-security-bulletin-pre-announcement-2/