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How to secure codeigniter Application?

CodeIgniter Security Class

CodeIgniter contain security class methods which will help to create a secure application and process input data. The methods are given below.

CodeIgniter xss_clean

XSS means Cross-site scripting, which is a type of security vulnerability found in web application. The XSS technique commonly used to trigger Javascript or other types of malicious code that attempt to hijack runnable code.

Usage of xss_clean(), we can stop the data and filter up, if any disallowed data is encountered it is rendered by xss_clean function and safe convert into the character entities.

Without the using of xss_clean(), encountered data via cookies and post, get method directly applied to the code, which is harmful.

Codeigniter provides “security” class which contains methods that help you create a secure application.

$data = $this->security->xss_clean($data);
You should use this function only when you are submitting data. The optional second Boolean parameter can also be used to check image file for XSS attack. This is useful for file upload facility. If its value is true, means image is safe and not otherwise.

Codeigniter File : form.php

View File : view_form.php

CSS File : style.css

CSRF (Cross-site Request Forgery)

To enable CSRF do the following settings in application/config/config.php file.
$config['csrf_protection'] = TRUE;

When you are creating form using form_open() function, it will automatically insert a CSRF as hidden field. You can also manually add the CSRF using the get_csrf_token_name() and get_csrf_hash() function. The get_csrf_token_name() function will return the name of the CSRF and get_csrf_hash() will return the hash value of CSRF.

The CSRF token can be regenerated every time for submission or you can also keep it same throughout the life of CSRF cookie. By setting the value TRUE, in config array with key ‘csrf_regenerate’ will regenerate token as shown below.

$config['csrf_regenerate'] = TRUE;
You can also whitelist URLs from CSRF protection by setting it in the config array using the key ‘csrf_exclude_uris’ as shown below. You can also use regular expression.

$config['csrf_exclude_uris'] = array('api/person/add');

Class Reference

Class CI_Security

SQL Injection Prevention

SQL injection is an attack made on database query. In PHP, we are use mysql_real_escape_string() function to prevent this along with other techniques but CodeIgniter provides inbuilt functions and libraries to prevent this.

We can prevent SQL Injection in CodeIgniter in the following three ways −

Escaping Queries

$this->db->escape() function automatically adds single quotes around the data and determines the data type so that it can escape only string data.

Query Biding

In the above example, the question mark(?) will be replaced by the array in the second parameter of query() function. The main advantage of building query this way is that the values are automatically escaped which produce safe queries. CodeIgniter engine does it for you automatically, so you do not have to remember it.

Active Record Class

Using active records, query syntax is generated by each database adapter. It also allows safer queries, since the values escape automatically.

Hiding PHP Errors

PHP Error Reporting Level
Different environment requires different levels of error reporting. By default, development will show errors but testing and live will hide them. There is a file called index.php in root directory of CodeIgniter, which is used for this purpose. If we pass zero as argument to error_reporting() function then that will hide all the errors.

Database Error
Even if you have turned off the PHP errors, MySQL errors are still open. You can turn this off in application/config/database.php. Set the db_debug option in $db array to FALSE as shown below. $db['default']['db_debug'] = FALSE;

Error log
Another way is to transfer the errors to log files. So, it will not be displayed to users on the site. Simply, set the log_threshold value in $config array to 1 in application/cofig/config.php file as shown below. $config['log_threshold'] = 1;

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