Re: [Full-disclosure] [Security-news] SA-CONTRIB-2012-040 - CKEditor and FCKeditor - multiple XSS, arbitrary code execution

Hi MaXe,

Thanks for the response.

You raise a good point that our advisories are not as educational as
they could be as a result of not fully detailing the attacks. I
recognize I'm writing this on the full-disclosure list, but many
members of our community prefer a long waiting period after the
vulnerability is announced to share details or POC so our "vendor"
stance matches that desire.

However, members of the Drupal community often give presentations
about secure coding at community events like user group meetings,
regional and national events (we call them Drupalcamps and
Drupalcons). They often use previous security advisories to
demonstrate 1) how to exploit the attack and 2) how to fix the attack.
It probably wouldn't be as useful for you personally, but for anyone
else interested here are some videos:

One example video where I demonstrate a few kinds of attacks and how
to prevent them in Drupal:

A search for "drupal security" finds tons of other videos, most of
which should have similar demonstrations:


On Fri, Mar 16, 2012 at 3:53 PM, InterN0T Advisories
<advisories@xxxxxxxxxxxx> wrote:
Hello Greg,

Thank you for your response.

After re-reading the advisory a couple of times, and after a few
communication attempts from Ustima who seems to have personal issues with
me, I realized that I was wrong, and that it wasn't the same bug that I
made an advisory for.

I am glad however, that you pointed out the difference, and also how your
advisories are designed (e.g., without PoC's limiting both attacks but also
free knowledge. Of course I could just research this bug discovered by you
or your team and release a working exploit), but the confusing part is also
the time-frame, as the CKEditor developers has recently fixed the bug I

Thanks again for clarifying the difference, but also responding to this
public mailing list.

Best regards,

On Thu, 15 Mar 2012 07:57:17 -0600, Greg Knaddison
<greg.knaddison@xxxxxxxxxx> wrote:
Hello MaXe,

Thanks for the feedback.

Our security advisories are meant to be a little opaque and do not
include a POC, so I can understand how these two issues could be
confusing: they both include XSS in something named (F)CKEditor.

However this issue is quite different from the one you identified.

Your advisory was about Javascript execution in html attributes inside
the Javascript/CKEditor tool itself. This vulnerability is about a
feature of the Drupal module written in PHP which responds to Ajax
requests and sends back text filtered using one of Drupal's Input

Users of Drupal who upgraded (F)CKEditor Javascript previously to
address the issue you identified in that code need to update their
Drupal module as well to fix the issue described in the advisory


On Wed, Mar 14, 2012 at 2:42 PM, InterN0T Advisories
<advisories@xxxxxxxxxxxx> wrote:
FYI, this bug was recently fixed by the CKEditor Developers, as the bug
itself was in the CKEditor module, not Drupal. (They just use it like
everyone else.)

Cartoon of the day:


Best regards,

PS: Sorry for the previous HTML e-mail.

On Wed, 14 Mar 2012 19:03:36 +0000 (UTC), security-news@xxxxxxxxxx
* Advisory ID: DRUPAL-SA-CONTRIB-2012-040
  * Project: CKEditor [1], FCKeditor [2] - WYSIWYG HTML editor
  * Version: 6.x, 7.x
  * Date: 2012-March-14
  * Security risk: Highly critical [3]
  * Exploitable from: Remote
  * Vulnerability: Cross Site Scripting, Cross Site Request Forgery,
    PHP code execution


CKEditor and its predecessor FCKeditor allow Drupal to replace
fields with the (F)CKEditor - a visual HTML WYSIWYG editor.

The modules have an AJAX callback that filters text to prevent Cross
scripting attacks on content edits. This AJAX callback function
number of bugs which allow attackers to chose which filter to execute
chosen text or bypass the filter entirely.

The vulnerability can be used to conduct Cross site scripting (XSS)
on privileged users. Attackers can also execute arbitrary PHP code if
core PHP module is enabled. This can happen either directly or by
privileged user to visit a page.

Direct execution of PHP code requires that the attacker has the

"access fckeditor" for FCKeditor 6.x
"access ckeditor" for CKEditor 6.x

No additional permissions are required to directly exploit the PHP
execution flaw on CKEditor 7.x.


  * FCKeditor 6.x-2.x versions prior to 6.x-2.3.
  * CKEditor 6.x-1.x versions prior to 6.x-1.9.
  * CKEditor 7.x-1.x versions prior to 7.x-1.7.

Drupal core is not affected. If you do not use the contributed
WYSIWYG HTML editor [4] module, there is nothing you need to do.

-------- SOLUTION

Install the latest version:

  * If you use the FCKeditor module for Drupal 6.x, upgrade to
    6.x-2.3 [5].
  * If you use the CKEditor module for Drupal 6.x, upgrade to CKEditor
  * If you use the CKEditor module for Drupal 7.x, upgrade to CKEditor

See also the CKEditor - WYSIWYG HTML editor [8] project page.

-------- REPORTED BY

  * Heine Deelstra [9] of the Drupal Security Team

-------- FIXED BY

  * Wiktor Walc [10] the module maintainer


The Drupal security team can be reached at security at or
contact form at [11].

Learn more about the Drupal Security team and their policies [12],
secure code for Drupal [13], and securing your site [14].

[3] http://drupal.orgteam/risk-levels

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