SQL Injection (SQLi) is a web based attack used by hackers to steal sensitive information from organizations through web applications. It is one of the most common application layer attacks used today. This attack takes advantage of improper coding of web applications, which allows hackers to exploit the vulnerability by injecting SQL commands into the prior web application.The underlying fact that allows for SQLi is that the fields available for user input in the web application allow SQL statements to pass through and interact with or query the database directly.
For example, let us consider a web application that implements a form-based login mechanism to store the user credentials and performs a simple SQL query to validate each login attempt. Here is a typical example:
select * from users where username=’admin’ and password=’admin123′;
If the attacker knows the username of the application administrator is admin, then he can log into the app as admin by entering the username as admin’– and without supplying any password. The query in the back-end looks like:
Select * from users where username=’admin’--’ and password=’xxx’;
Note the comment sequence (–-) causes the followed query to be ignored, so query executed is equivalent to:
Select * from users where username=’admin’;
Hence the password check is bypassed and the attacker is logged into the app as admin. SQL Injection can be tested in two ways - Manual Pen-Testing & Automation.
1) Manual Pen-Testing: This is the process of detecting & exploiting the vulnerability manually. We need to test the vulnerability manually by passing the malicious strings and exploit it. I’ll give a clear explanation of exploiting SQLi manually in my next post.
2) Automated: This can be done by running the tools. There are many tools to find and exploit the SQLi vulnerability, some of them are SQLMAP, ABSINTHE, SQL NINJA, The Mole, etc… . I would love to use some tool which can be attached to a proxy that I use in my work regularly. So I chose SQLMap plugin for burp.
SQLMAP is an open source penetration testing tool that helps in automating the process of detecting and exploiting SQL injection vulnerabilities and taking full access over the database servers. SQLMAP comes with powerful detecting engine, and many niche features for the penetration tester and wide range of switches lasting from database fingerprinting, data fetching from the database, accessing the underlying file system and executing the commands on Operating System via Out-of-band Connections.
Since SQLMAP is developed in python it is a portable application, meaning that it will work in any operating system that supports python.
SQLMAP burp plug-in:
When we audit a web application, we normally configure an intermediate proxy to have more control over the request and response parameters. SQLMAP plug-in is an add-on feature that we can configure to the burp through which we can redirect a URL or a request directly to the SQLMAP with a single mouse click.
1. Download the plugin zip file from the following URL: http://code.google.com/p/gason/downloads/list
2. Unzip the file and keep it in the same folder where burp proxy is located.
3. Then execute the following command to run the burp with plug-in.
Java –classpath burpplugins.jar:”burpsuite_v184.108.40.206.jar” burp.StartBurp
Java –classpath burpsuite_v220.127.116.11.jar;burpplugins.jar burp.StartBurp
*Replace the burpsutie with the appropriate version that you are using. In my case I am using burpsuite_v18.104.22.168.jar. We also need to download the SQLMAP tool as we need to supply the executable to the burp plug-in.
Setting up SQLMAP:
1. Download and Install python 2.7 -http://www.python.org/getit/
2. Download sqlmap - https://github.com/sqlmapproject/sqlmap
3. Unzip the name.zip file to sqlmap directory.
For Ubuntu or Linux, run the below commands from the terminal
> Sudo apt-get install python-tk python2.7
> git clone git://github.com/sqlmapproject/sqlmap.git
> cd sqlmap
> wget http://gui-for-sqlmap.googlecode.com/files/sqm-60712.zip
> unzip sqm-60712.zip
Setting up the environment:
- If you are using OWASP broken web application, then simply access one of the vulnerable site from your local browser where you are running SQLMAP.
- If you don’t use OWASP broken web application, then you need to set up a virtual machine that has a web server to host the vulnerable web application.
- Configure another VM with ubuntu where the attacker runs SQLMAP
Configuring the Proxy:
- If you are using Mozilla Firefox, then go to Edit > Preferences > Advanced > Network > settings and select “Manual Proxy Configuration” by enabling the radio button. Run the HTTP proxy with local-host and the port in which the proxy is running.
- If you are using Chrome, then go-to settings > Show Advanced Options > Network > Change proxy Settings > Connections > Lan settings.
How to use the plug-in:
Once you load the plug-in, then it is very easy to make use of it. Run the burp proxy with loaded plug-in. In the “site map” tab under the “target” you can see the particular domain that you are trying to test for SQLI and all the crawled pages related to the domain. On the right side click on the URL that you want to test, you can see the request parameters of the URL in the bottom panel. Right click on the request parameters and you can see the option “Send to sqlmap” as shown in the figure below.
Then you can see a new window (SQLMap wrapper) that will allow you to configure sqlmap. Below Image gives you a clear view of the wrapper.
Now lets have an over view of configuration features of the wrapper. In the “Target” text box specify the URL that you are willing to test. (Normally it will be filled by default as you have sent the request parameters previously, if needed you can change the URL).
Specify the method on which the domain is accessible (GET/POST). In the “Bin-path” give sqlmap executable.
If you are aware of the DBMS of the web application, specify the database by selecting one of the options listed in the dropdown list. By default “auto” is selected which means that the SQLMAP wrapper tries with all the databases listed in the dropdown list to find out the database used by the application.
You can enumerate the database users, passwords, roles, privileges, databases etc by selecting the appropriate option from the Action drop down list. By default it is set to “auto” which means it will try to enumerate all the options listed in the drop down list in the sequential order.
If you are aware of the databases, users, tables, or columns, you can enumerate it by simply specifying it in the Database options.
Tampers are a kind of special characters or symbols that you are willing to insert into the query while pen-testing the application.
Once we configure the SQLMAP click on the “RUN”, this will open a new tab with execution of the program with the configuration that you have given to the wrapper or the SQLMAP. We can make any number of simultaneous execution tabs with difference instances. Below image shows the output tab.
Bored with theory, now lets see an example, the below URL is a vulnerable site for practicing the SQLI. You can also find the SQLI practice URL’s by goggling.
Id parameter in the above URL is vulnerable to SQLI; lets find it out through our SQLMAP wrapper (Burp suite plug-in).
Open the URL in the browser for which the proxy has been configured. In the proxy (burp) go to the “site map” and click on the URL and send it to the sqlmap by right clicking on the response parameters of the website, as I mentioned previously. Figure below shows you the wrapper opened for the above mentioned URL.
The target specifies the URL we are testing, cookie specifies the cookie or session id. Wrapper automatically identifies the positions in the URL where SQLI can be injected and specifies list of the parameters in “Parameters to test” text area (in our case we have only one possibility for injection which is “id” parameter).
In this example I have configured the SQLMAP wrapper to enumerate the list of databases that are configured in the backend database.
Above figure shows you the output tab which intend displays you how the plug-in tried to exploit the SQLI vulnerability in different ways
We can see that initially the wrapper tried to exploit the vulnerability by using “Boolean-based blind SQLI” by using AND operator. The payload shows how the tool tried to exploit the vulnerability. Here we can see the payload: id=22 AND 4626=4626, which is equivalent to the following URL:
http://192.168.2.3/news-and-events.php?id=22 AND 4626=4626
As the URL is always true, the above URL returns the same page as of the original URL.
In the second trail it tried “error-based SQLI”. Later by using UNION operator.
From the above figure we can observe more server details like web server, Operating System, back-end DBMS.
“Information_schema” and “nilakantatrust” are the two databases that are used by the web application.
Now let us try to enumerate all the tables and the columns of the tables from the above databases. To do so configure the SQLMAP wrapper Action field with the option “Enumerate database tables and columns”. Below Figure shows you the same.
Below figure shows us the tables of the database “nilakantatrust”.
Let us see the columns of these tables. Figure below shows the columns and their data types of two tables “est_notice” and “est_news” of nilakantatrust database.
We can also dump complete database by selecting the option “dump dbms databases”. And also store complete data into a file by using the option “save to file” in the output tab.
Above figure shows the dumped data of the table “est_admin” from “nilakantatrust” database and storing it into a file.
SQLMAP is a powerful tool which is used to automate the process of detecting and exploiting the SQLI.
I have written this article for infosec institute. Take a look at the web application security course offered by infosecinstitute.