Learn About AJAX Security


The advent of Web 2.0 brought about a new technique in building web applications, Asynchronous, JavaScript, and XML. AJAX is a faster and interactive technology that has found great favor among modern businesses today. With it comes a combination of JavaScript, HTML, CSS, and XML to build one useful technique that makes web application interactivity faster and affordable in terms of bandwidth consumption. This article is a description of AJAX and its security issues.


Conventional web sites were known to be slower and consumed more bandwidth because of the way they connected to the server. It would take a page to reload to connect to the server using synchronous connection. This meant more bandwidth consumption and slower response from web applications. On the other hand, AJAX is a browser technology that uses asynchronous means to communicate to the server. This means that you can communicate with the server to update certain portions of a page without having to reload the whole page.

A good example of AJAX in use is the Google create account page which recognizes a username in use soon after a user enters their suggested username. This means that in the background the page has communicated with the Google server to check if the name exists and show results without having to reload the entire page.

It is considered the most feasible Rich Internet Application (RIA) to date. AJAX makes use of Open Standards that include HTML and CSS for the presentation of data, XML for data storage and transfers to and from the server, XMLHttpRequest objects in the browser to fetch data from the server, and finally JavaScript for interactivity. AJAX can also transfer data in JSON or plain-text.

Security Issues with AJAX

AJAX applications only use a different technique to connect to the server. However, they use the same security schemes to connect to the server. This entails that you still have to include your authentication, authorization, and data protection methods in the web.xml file or program. AJAX applications bear the same vulnerabilities as ordinary or conventional web applications. In as much as people prefer the swiftness and the advanced interactivity of AJAX applications, some are misled to believe that AJAX web applications are more secure than ordinary web applications.

AJAX applications are known to have session management vulnerabilities and a lot of loopholes in the hidden URLs which carry AJAX requests to the server.

The AJAX engine makes use of JavaScript to transfer user requests/commands and transforms them into function calls. The AJAX engine sends these function calls in plain-text to the server that may be intercepted by attackers to reveal database information, variable names, or any other confidential user data that may be used by the attacker maliciously.

AJAX-based applications are also vulnerable to Cross-Site Request Forgery (CRSF) and Cross-Site Scripting (XSS). Although it is not that easy to exploit CSRF on AJAX applications because the requests are hidden, attackers may be able to create a script that can steal a user’s session token and by so doing be able to steal the user’s session remotely.

This can be avoided by creating random complex tokens for the AJAX requests which are not identified by the attackers. The server embeds the complex token on the page and checks for it each time the users make a request to the server and if it is any different the server does not process the request.

To ensure AJAX security against XSS, the application has to strictly sanitize user input and output. The use of JS functions such as ‘document.write()’, ‘innerHTML()’, ‘eval()’, ‘write()’ may make it possible for XSS attacks in AJAX web applications.


AJAX is a very fast and affordable browser technology but needs to be treated just like any other web application when it comes to security. Organizations need to do thorough scanning of their AJAX applications just like on conventional web applications to ensure absolute security from common vulnerabilities.

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