In this age of the world wide web, creating and owning a website has become easier than it ever was. Tools like WordPress have further simplified the process and you can set up your own website in just a few hours without even having to write a single line of code. Each website contains data, and this data is stored by using some way or the other. There are a number of ways of storing data in a website and one very common way to accomplish this task is to use a database. The databases are of different types like the SQL database or the XML database. When a XML database is used for the storage of data in a website, then the stored data can get corrupted or modified and this attack on the security of the data stored in a XML database is known as XML injection.
To understand the concept of XML injection, first you need to be familiar with the concept of a database. Here is a great course about the basics of the database management system which will introduce you to the concept of a database. Databases like the SQL database or the XML database are highly useful and the most commonly used methods for data storage for websites but they can be prone to attacks like SQL injection or XML injection. Here we are going to study about XML injection in detail. How this causes a threat to the security of data and how this threat can be prevented will also be discussed. The XML database and the related concepts will be discussed here in detail, but to find more about the SQL database you can read this highly informative article about the SQL database here.
What is XML Injection?
When the data in a website is stored in a XML database, then this data is accessed by using a method known as XPath generation. In this method, an XPath query is generated after the user provides the input to the system and the required data is accessed. The problem arises when the input provided by the user is not properly filtered by the system.
Let us take an example. Here we have a XML file which stores the user data. The file is given as,
<user ID =1>
This file stores the user data for the administrator. Now after the input is provided by the user, an XPath query is generated. The problem arises if this input is not properly monitored and in this case the attacker can easily manipulate the XPath query by programming it as per his needs and can access any information on the database. In the above example, by specifying the user ID as 1, the attacker can even log in as the administrator. This will empower him to make any changes he wishes to make to the system and will cause a big threat to the security of the system.
To get a better idea about the XPath queries and about programming in XML in general, you can check out this amazing course about learning XPath structure and syntax. This course will help you in understanding the concepts being discussed here in a better way.
In the example which has been discussed above, the XPath query will be generated in PHP. To better understand the above example and to utilize these concepts in real world situations, a basic knowledge of PHP would be of great help. Here is a great course about the basics of PHP which will give you the required knowledge about all the basic tools and statements used in PHP.
Threat Posed by XML Injection on the Security
A successful XML injection attack poses a very high risk for a website. The attacker can seal the entire database, and can even log in as the administrator of the website. This means that all the sensitive data stored in the database will be accessible to the hacker and he can make any kind of changes he would like to make to the website. This is the biggest threat that the XML injection poses to the security of a website.
Preventing XML Injection
The prevention of XML injection can be done by properly managing and sanitizing any user input before it is allowed to reach the main program code. The best method is to consider all the user input as unsafe and to properly monitor this input. Most types of the XML injection attacks can be prevented by simply removing all the single and double quotes from the user input. Though this method is very convenient but proper care needs to be taken.
Many problems can arise if proper monitoring is not done. Say the username entered by a user contains a valid quote, but this quote will get removed by using this method and this username will not be expected by the system. Hence the system should be capable of recognizing and allowing these inputs and this can be achieved by using proper functions and syntax from the XML library.
Here is a great course about the basics of XML programming and this course will help you in learning about the basics of XML programming for properly monitoring and also sanitizing all user input before it reaches the main system program. This will ensure that the unwanted input remains away from the system and the required valid user inputs are accepted by the system. This will ensure the safety as well as help the system work correctly and will help the system to remain safe from XML injection.