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Re: CVE affected for PHP 5.3.9 ?
From: Kurt Seifried <kseifried () redhat com>
Date: Fri, 13 Jan 2012 21:41:42 -0700
On 01/13/2012 03:30 PM, Nicolas Grégoire wrote:
Le vendredi 13 janvier 2012 à 13:50 -0700, Kurt Seifried a écrit :
Again I'm still not clear on what/how a security boundary is being
crossed. How does this elevate privileges or give you remote access
that you wouldn't already if you can upload arbitrary PHP scripts?
XSLT 1.0, as defined by the W3C, doesn't allow to save the result of a
XSL transformation to the file system. This feature is an extension
provided by libxslt itself. As PHP 5 uses libxslt as its XSLT engine,
PHP applications parsing external/untrusted XSLT expose this feature.
An attacker can provide specially crafted XSLT code which will create an
arbitrary file with chosen content ("0wn3d.php" in my example). Then,
this PHP file is requested by the attacker and executed.
Somewhat similar to an undocumented file upload feature ...
Right, but in this case to upload the file you need to put a custom php
script on the server, so no additional privilege or access is gained. Is
it common for these scripts to allow a remote user to specify the output
location (this seems unlikely to me)?
-- Kurt Seifried / Red Hat Security Response Team