SQL Injection Attack Lab - Computing and Information Studies
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1. if get_magic_quotes_gpc and FALSE After removing and False the countermeasure within the if block will be executed if the magic quote mechanism is turned off To help describe your observations you should print out the SQL queries and see how the mechanism affect the queries Please go to the guideline section to learn how to print out information in PHP programs e Task 3 3 Escaping Special Characters using mysql_real_escape_string A better way to escape data to defend against SQL injection is to use database specific escaping mechanisms in stead of relying upon features like magical quotes MySQL provides an escaping mechanism called mysql_real_escape_st ring which prepends backslashes to a few special characters includ ing x00 n r 7 and x1A Please use this function to fix the SQL injection vulner abilities identified in the previous tasks You should disable the other protection schemes described in the previous tasks before working on this task e Task 3 4 Prepare Statement A more general solution to separating data from SQL logic is to tell the database exactly which part is the data part and which part is the logic part MySQL provides the prepare statement mechanism for this purpose db new mysqli localhost user pass db Sstmt Sdb gt prepare SELECT FROM users WHERE name AND age Sstmt gt bind_param si user Sage Sstmt gt execute Using th2. hosting feature in Apache could be used to host several web sites or URLs on the same machine A configuration file named default in the directory etc apache2 sites available contains the necessary directives for the configuration 1 The directive NameVirtualHost gt instructs the web server to use all IP addresses in the ma chine some machines may have multiple IP addresses 2 Each web site has a VirtualHost block that specifies the URL for the web site and directory in the file system that contains the sources for the web site For example to configure a web site with URL http www examplel com with sources in directory var www Example_1 and to configure a web site with URL http www example2 com with sources in directory var www Example_2 we use the following blocks lt VirtualHost gt ServerName http www examplel com DocumentRoot var www Example_1 lt VirtualHost gt lt VirtualHost gt ServerName http www example2 com DocumentRoot var www Example_2 lt VirtualHost gt You may modify the web application by accessing the source in the mentioned directories For example with the above configuration the web application http www examplel com can be changed by modifying the sources in the directory var www Example_1 Laboratory for Computer Security Education 3 2 2 Turn Off the Countermeasure PHP provides a mechanism to automatically defend against SQL inject
3. will not take effect Please turn on off the magic quote mechanism and see how it help the protection Please be noted that starting from PHP 5 3 0 the version in our provided VM is 5 2 6 the feature has been DEPRE CATED due to several reasons Portability Assuming it to be on or off affects portability Most code has to use a function called get_magic_quotes_gpc to check for this and code accordingly Laboratory for Computer Security Education 6 Performance and Inconvenience not all user inputs are used for SQL queries so mandatory escaping all data not only affects performance but also become annoying when some data are not supposed to be esecaped e Task 3 2 Escaping Special Characters using addslashes A PHP function called addslashes can also achieve what the magic quote does The original phpBB2 code uses addslashes to defend against the SQL injection attacks if the magic quote is not turned on Please look at the common php file in var www SQL SQLLabMysgqlPhpbb common php is included by login php so it will be executed whenever login php is executed We actually commented out the protection in phpBB2 to make the SQL injection possible Please turn the protection back on to see the difference by removing and FALSE from the the following line we added and False to bypass this block of code Please describe how this protection scheme help defend against your SQL injection attacks
4. Laboratory for Computer Security Education 1 SQL Injection Attack Lab Copyright 2006 2010 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview SQL injection is a code injection technique that exploits the vulnerabilities in the interface between web applications and database servers The vulnerability is present when user s inputs are not correctly checked within the web applications before sending to the back end database servers Many web applications take inputs from users and then use these inputs to construct SQL queries so the web applications can pull the information out of the database Web applications also use SQL queries to store information in the database These are common practices in the development of web applications When the SQL queries are not carefully constructed SQL injection vulnerabilities can occur SQL injection attacks is one of the most frequent attacks on web applications In this lab we modified a web application called phpBB and disabled several co
5. ation In web applications whatever are printed out by the server side program is actually displayed in the web page sent to the users the debugging printout may mess up with the web page There are several ways to solve this problem A simple way is to print out all the information to a file For example the following code snippet can be used by the server side PHP program to print out the value of a variable to a file SmyFile tmp mylog txt Sfh fopen SmyFile a or die can t open file SData a string fwrite fh Data n fclose Sfh A useful Firefox Add on Firefox has an add on called Tamper Data it allows you to modify each field in the HTTP request before the request is sent to the server For example after clicking a button on a web page an HTTP request will be generated However before it is sent out the Tamper Data add on intercepts the request and gives you a chance to make an arbitrary change on the request This tool is quite handy in this lab The add on only works for Firefox versions 3 5 and above If your firefox has an earlier version you need to upgrade it for this add on In our most recently built virtual machine image SEEDUbuntu9 Aug 2010 Firefox is already upgraded to version 3 6 and the Tamper Data add on is already installed 5 Submission You need to submit a detailed lab report to describe what you have done and what you have observed You also need to prov
6. e are injected into the data field To solve this problem it is important to ensure that the view of the boundaries are consistent in the server side code and in the database There are various ways to achieve this this objective e Task 3 1 Escaping Special Characters using magic_quotes_gpc In the PHP code if a data variable is the string type it needs to be enclosed within a pair of single quote symbols For example in the SQL query listed above we see username Susername The single quote symbol surrounding username basically tries to seperate the data in the username variable from the code Unfortunately this separation will fail if the contents of username include any single quote Therefore we need a mechanism to tell the database that a single quote in Susername should be treated as part of the data not as a special character in SQL All we need to do is to add a backslash before the single quote PHP provides a mechanism to automatically add a backslash before single quote double quote backslash and NULL characters If this option is turned on all these characters in the inputs from the users will be automatically escaped To turn on this option go to etc php5 apache2 php ini and add magic_quotes_gpc On the option is already on in the VM provided to you Remeber if you update php ini you need to restart the apache server by running sudo service apache2 restart othewise your change
7. e prepare statement mechanism we divide the process of sending a SQL statement to the database into two steps The first step is to send the code i e the SQL statement without the data that need to be plugged in later This is the prepare step After this step we then send the data to the database using bind_param The database will treat everything sent in this step only as data not as code anymore Even if the magic quote option is turned on in php ini a statement in the beginning of common php turned off the magic quote at runtime This is done using set_magic_quotes_runtime 0 That is why get_magic_quotes_gpc will be false It should be noted that turning on the magic quotes at runtime does not affect the inputs provided by the users i e those in _GET and _POST It only affects the other inputs e g input from files etc The function set_magic_quotes_runtime is also deprecated starting from PHP version 5 3 0 Laboratory for Computer Security Education 7 Please use the prepare statement mechanism to fix the SQL injection vulnerability in the phpBB2 code In the bind_param function the first argument si means that the first parameter Suser has a string type and the second parameter Sage has an integer type 4 Guidelines Print out debugging information When we debug traditional programs e g C programs without using any debuging tool we often use printf to print out some debugging inform
8. et more points use your own creativity to find out first hand evidences If in case you find ways to succeed in the attacks you will be awarded bonus points 3 2 Task 2 30 Points SQL Injection on UPDATE Statements When users want to update their profiles in phpBB2 they can click the Profile link and then fill in a form to update the profile information After the user sends the update request to the server an UPDATE SQL statement will be constructed in include usercp_register php The objective of this state ment is to modify the current user s profile information in phpbb_users table There is a SQL injection vulnerability in this SQL statement Please find the vulnerability and then use it to do the following e Change another user s profile without knowing his her password For example if you are logged in as Alice your goal is to use the vulnerability to modify Ted s profile information including Ted s password After the attack you should be able to log into Ted s account 3 3 Task 3 40 Points Countermeasures The fundamental problem of SQL injection vulnerability is the failure of separating code from data When constructing a SQL statement the program e g PHP program knows what part is data and what part is code Unfortunately when the SQL statement is sent to the database the boundary has disappeared the boundaries that the SQL interpreter sees may be different from the original boundaries if cod
9. ide explanation to the observations that are interesting or surprising
10. ion attacks The method is called magic quote and more details will be introduced in Task 3 Let us turn off this protection first this protection method is deprecated after PHP version 5 3 0 1 2 3 4 2 3 Go to etc php5 apache2 php ini Find the line magic_quotes_gpc On Change it to this magic_quotes_gpc Off Restart the apache server by running sudo service apache2 restart Note for Instructors If the instructor plans to hold lab sessions for this lab we suggest that the following background materials be covered in the lab sessions 1 How to use the virtual machine Firefox web browser the LiveHttpHeaders and Tamper Data add ons Brief introduction to SQL only needs to cover the basic structure of the SELECT UPDATE and INSERT statements A useful online SQL tutorial can be found at http www w3schools com sql How to operate the MySQL database only the basics The account information about the MySQL database can be found in the User Manual of the Pre built Ubuntu 9 Virutal Machine which can be downloaded from our SEED web page Brief introduction to PHP only needs to cover the very basics Students who have a background in C C Java or other language should be able to pick up this script language quite quickly 3 Lab Tasks 3 1 Task 1 30 Points SQL Injection Attack on SELECT Statements For this task you will use the web application accessible via the URL www sq
11. llabmysqlphpbb com which is phpBB2 configured with MySQL database inside your virtual machine Before you start to use phpBB2 the system will ask you to login The authentication is implemented by Login php on the server side This program will display a login window to the user and ask the user to type their username and password The login window is displayed in the following Laboratory for Computer Security Education 4 Username Password Log me on automatically each visit Log in Forgot my password Once the user types the username and password the login php program will use the user provided data to find out whether they match with the username and user_password fields of any record in the database If there is a match it means the user has provided a correct username and password combination and should be allowed to login Like most other web applications PHP programs interact with their back end databases using the standard SQL language In phpBB2 the following SQL query is constructed in login php to authenticate users SELECT user_id username user_password user_active user_level user_login_tries user_last_login_try FROM USERS_TABLE WHERE username Susername AND user_password md5 Spassword if found one record then allow the user to login In the above SQL statement the USERS_TABLE is a macro in php which will be replaced by the users ta ble name
12. phpbb_users username is a variable that holds the string typed in the Username textbox and Spassword is a variable that holds the string typed in the Password textbox User s inputs in these two textboxs are placed directly in the SQL query string SQL Injection Attacks on Login There is a SQL injection vulnerability in the above query Can you take advantage of this vulnerability to achieve the following objectives e Can you log into another person s account without knowing the correct password e Can you find a way to modify the database still using the above SQL query For example can you add a new account to the database or delete an existing user account Obviously the above SQL statement is a query only statement and cannot update the database However using SQL injection you can turn the above statement into two statements with the second one being the update statement Please try this method and see whether you can successfully update the database To be honest we are unable to achieve the update goal This is because of a particular defense mechanism implemented in MySQL In the report you should show us what you have tried in order to modify the database You should find out why the attack fails what mechanism in MySQL has Laboratory for Computer Security Education 5 prevented such an attack You may look up evidences second hand from the Internet to support your conclusion However a first hand evidence will g
13. ult You have to first start the web server using the following command o sudo service apache2 start Laboratory for Computer Security Education 2 The phpBB2 Web Application The phpBB2 web application is already set up in the pre built Ubuntu VM image We have also created several user accounts in the phpBB2 server The password information can be obtained from the posts on the front page You can access the phpBB2 server using the following URL the apache server needs to be started first http www sqllabmysqlphpbb com The source code of web application is located at var www SQL SQLLabMysqlPhpbb Configuring DNS This URL is only accessible from inside of the virtual machine because we have modified the etc hosts file to map the domain name www sqllabmysqlphpbb com to the vir tual machine s local IP address 127 0 0 1 You may map any domain name to a particular IP address using the etc hosts For example you can map http www example com to the local IP address by appending the following entry to etc hosts file 127 0 0 1 www example com Therefore if your web server and browser are running on two different machines you need to modify the etc hosts file on the browser s machine accordingly to map www sqllabmysqlphpbb com to the web server s IP address Configuring Apache Server In the pre built VM image we use Apache server to host all the web sites used in the SEED labs The name based virtual
14. untermeasures imple mented by phpBB2 As the results we created a version of phpBB that is vulnerable to the SQL Injection attack Although our modifications are artificial they capture the common mistakes made by many web de velopers Students goal in this lab is to find ways to exploit the SQL Injection vulnerabilities demonstrate the damage that can be achieved by the attacks and master the techniques that can help defend against such attacks 2 Lab Environment You need to use our provided virtual machine image for this lab The name of the VM image that supports this lab is called SEEDUbuntu9 Aug 2010 which is built in August 2010 If you happen to have an older version of our pre built VM image you need to download the most recent version as the older version does not work for this lab Go to our SEED web page http www cis syr edu wedu seed to get the VM image 2 1 Environment Configuration In this lab we will need three things 1 the Firefox web browser 2 the apache web server and 3 the phpBB2 message board web application For the browser we need to use several Firefox add ons to inspect and or modify the HTTP requests and responses The pre built Ubuntu VM image provided to you has already installed the Firefox web browser with the required extensions Starting the Apache Server The apache web server is also included in the pre built Ubuntu image However the web server is not started by defa
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