Hey!!!!! Guyz Today We Explain About XSS Cross Site Scripting Attack What is Cross Site Scripting? Hackers are constantly experimenting with a wide repertoire of hacking techniques to compromise websites and web applications and make off with a treasure trove of sensitive data including credit card numbers, social security numbers and even medical records. Cross Site Scripting (also known as XSS or CSS) is generally believed to be one of the most common application layer hacking techniques. In the pie-chart below, created by the Web Hacking Incident Database for 2011 (WHID) clearly shows that whilst many different attack methods exist, SQL injection and XSS are the most popular. To add to this, many other attack methods, such as Information Disclosures, Content Spoofing and Stolen Credentials could all be side-effects of an XSS attack. The Methods Hackers Use In general, cross-site scripting refers to that hacking technique that leverages vulnerabilities in the code of a web application to allow an attacker to send malicious content from an end-user and collect some type of data from the victim. Today, websites rely heavily on complex web applications to deliver different output or content to a wide variety of users according to set preferences and specific needs. This arms organizations with the ability to provide better value to their customers and prospects. However, dynamic websites suffer from serious vulnerabilities rendering organizations helpless and prone to cross site scripting attacks on their data. A web page contains both text and HTML markup that is generated by the server and interpreted by the client browser. Web sites that generate only static pages are able to have full control over how the browser interprets these pages. Web sites that generate dynamic pages do not have complete control over how their outputs are interpreted by the client. The heart of the issue is that if mistrusted content can be introduced into a dynamic page, neither the web site nor the client has enough information to recognize that this has happened and take protective actions. (CERT Coordination Center). Cross Site Scripting allows an attacker to embed malicious JavaScript, VBScript, ActiveX, HTML, or Flash into a vulnerable dynamic page to fool the user, executing the script on his machine in order to gather data. The use of XSS might compromise private information, manipulate or steal cookies, create requests that can be mistaken for those of a valid user, or execute malicious code on the end-user systems. The data is usually formatted as a hyperlink containing malicious content and which is distributed over any possible means on the internet. As a hacking tool, the attacker can formulate and distribute a custom-crafted CSS URL just by using a browser to test the dynamic website response. The attacker also needs to know some HTML, JavaScript and a dynamic language, to produce a URL which is not too suspicious-looking, in order to attack a XSS vulnerable website. Any web page which passes parameters to a database can be vulnerable to this hacking technique. Usually these are present in Login forms, Forgot Password forms, etc… N.B. Often people refer to Cross Site Scripting as CSS or XSS, which is can be confused with Cascading Style Sheets (CSS). The Theory of XSS In a typical XSS attack the hacker infects a legitimate web page with his malicious client-side script. When a user visits this web page the script is downloaded to his browser and executed. There are many slight variations to this theme, however all XSS attacks follow this pattern, which is depicted in the diagram below. How Cross Site Scripting Works As a web developer you are putting measures in place to secure the first step of the attack. You want to prevent the hacker from infecting your innocent web page with his malicious script. There are various ways to do that, and this article goes into some technical detail on the most important techniques that you must use to disable this sort of attack against your users. XSS Attack Vectors So how does a hacker infect your web page in the first place? You might think, that for an attacker to make changes to your web page he must first break the security of the web server and be able to upload and modify files on that server. Unfortunately for you an XSS attack is much easier than that. Internet applications today are not static HTML pages. They are dynamic and filled with ever changing content. Modern web pages pull data from many different sources. This data is amalgamated with your own web page and can contain simple text, or images, and can also contain HTML tags such as for paragraph, for image and for scripts. Many times the hacker will use the ‘comments’ feature of your web page to insert a comment that contains a script. Every user who views that comment will download the script which will execute on his browser, causing undesirable behaviour. Something as simple as a Facebook post on your wall can contain a malicious script, which if not filtered by the Facebook servers will be injected into your Wall and execute on the browser of every person who visits your Facebook profile. Hope You guyzz are enjoy the post #H4ckz
Posted on: Tue, 22 Apr 2014 04:37:29 +0000
Trending Topics
Recently Viewed Topics
© 2015