So, what an XSS is actually able to do:
- Steal user cookie
- Retrieve forms data, including CSRF token
- Retrieve the content of the DOM
- Retrieve local/session storage
- Capture user’s key pressed
- Capture the full DOM
- Capture the page screenshot
- Take a webcam snapshot
- Impersonate or masquerade as the victim user.
- Carry out any action that the user is able to perform.
- Read any data that the user is able to access.
- Capture the user's login credentials.
- Perform virtual defacement of the web site.
- Inject trojan functionality into the web site.
What can be done by XSS attack?
XSS enables an attacker to execute malicious scripts in another user's browser. However, instead of attacking the victim directly, the attacker exploits a vulnerability in a website the victim visits and gets the website to deliver the malicious script.
What can you steal with XSS?
Stealing cookies is a traditional way to exploit XSS. Most web applications use cookies for session handling. You can exploit cross-site scripting vulnerabilities to send the victim's cookies to your own domain, then manually inject the cookies into the browser and impersonate the victim.
Can XSS inject a keylogger?
A keylogging script that can be injected into websites vulnerable to cross-site scripting. The script tracks user keypresses by concatenating each keypress into a string that is POSTed to a server. The script can be found in file keylogscript.
Is it illegal to XSS?
Any type of Penetration Testing is illegal unless and until you have written permission of the System Owner(a.k.a Company).
Does XSS steal data?
Depending on the functionality and data processed by the vulnerable application, XSS vulnerabilities can pose a significant risk to the business. Attackers could steal confidential information, perform unauthorized activities, and take over the entire web sessions of the victim users.
Can XSS steal cookies?
Cookie Theft This generally happens when the site has a vulnerability and the attacker uses something known as cross-site scripting (XSS) to exploit that vulnerability.
Can XSS get cookie?
If an attacker is able to inject a Cross-site Scripting (XSS) payload on the web application, the malicious script could steal the user's cookie and send it to the attacker. The attacker can then use the cookie to impersonate the user in the web application.
What are the 3 different types of XSS attacks?
These 3 types of XSS are defined as follows:Reflected XSS (AKA Non-Persistent or Type I) ... Stored XSS (AKA Persistent or Type II) ... DOM Based XSS (AKA Type-0)
How to Test for Cross-site scripting Vulnerabilities
See the latest OWASP Testing Guide article on how to test for the various kinds of XSS vulnerabilities.
Stored and Reflected XSS Attacks
XSS attacks can generally be categorized into two categories: stored and reflected. There is a third, much less well-known type of XSS attack called DOM Based XSS that is discussed separately here.
Other Types of XSS Vulnerabilities
In addition to Stored and Reflected XSS, another type of XSS, DOM Based XSS was identified by Amit Klein in 2005. OWASP recommends the XSS categorization as described in the OWASP Article: Types of Cross-Site Scripting, which covers all these XSS terms, organizing them into a matrix of Stored vs. Reflected XSS and Server vs.
How to Determine If You Are Vulnerable
XSS flaws can be difficult to identify and remove from a web application. The best way to find flaws is to perform a security review of the code and search for all places where input from an HTTP request could possibly make its way into the HTML output. Note that a variety of different HTML tags can be used to transmit a malicious JavaScript.
How to Protect Yourself
The primary defenses against XSS are described in the OWASP XSS Prevention Cheat Sheet.
Alternate XSS Syntax
XSS attacks may be conducted without using <script>...</script> tags. Other tags will do exactly the same thing, for example: <body onload=alert ('test1')> or other attributes like: onmouseover, onerror.
Example 1
The following JSP code segment reads an employee ID, eid, from an HTTP request and displays it to the user.
XSS: What it is, how it works, and how to prevent it
If you’re a developer, chances are that you’ve heard of cross-site scripting. Cross-site scripting, commonly known as XSS, is one of the top 10 most common web security vulnerabilities according to OWASP. Cross-site scripting continues to be a major problem in many web applications, and it can result in some serious problems.
What is XSS?
Cross-site scripting occurs when attackers or malicious users can manipulate a web site or web application to return malicious JavaScript to users.
DOM-based XSS
This type of XSS occurs when user input is manipulated in an unsafe way in the DOM (Document Object Map) by JavaScript. For example, this can occur if you were to read a value from a form, and then use JavaScript to write it back out to the DOM.
Reflected XSS
Reflected XSS is similar to DOM-based XSS: it occurs when the web server receives an HTTP request, and “reflects” information from the request back into the response in an unsafe manner. An example would be where the server will place the requested application route/URL in the page that is served back to the user.
Stored XSS
Stored XSS occurs when user-created data is stored in a database or other persistent storage and is then loaded into a page. Common examples of types of applications that do this include forums, comment plugins, and similar applications.
Why does XSS Matter?
This is all well and good, you might think, but what does it matter? So what if someone can make an alert () bubble pop up on my webpage? That's a fair question - most XSS examples, including the ones I provided above, use alert () as a proof-of-concept.
Preventing XSS Attacks
XSS vulnerabilities are incredibly easy to create by accident. To prevent them, you need to put in place good coding practices, code review processes, and multiple layers of defense.
What is cross-site scripting (XSS)?
Cross-site scripting (also known as XSS) is a web security vulnerability that allows an attacker to compromise the interactions that users have with a vulnerable application. It allows an attacker to circumvent the same origin policy, which is designed to segregate different websites from each other.
How does XSS work?
Cross-site scripting works by manipulating a vulnerable web site so that it returns malicious JavaScript to users. When the malicious code executes inside a victim's browser, the attacker can fully compromise their interaction with the application.
XSS proof of concept
You can confirm most kinds of XSS vulnerability by injecting a payload that causes your own browser to execute some arbitrary JavaScript. It's long been common practice to use the alert () function for this purpose because it's short, harmless, and pretty hard to miss when it's successfully called.
Reflected cross-site scripting
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.
Stored cross-site scripting
Stored XSS (also known as persistent or second-order XSS) arises when an application receives data from an untrusted source and includes that data within its later HTTP responses in an unsafe way.
DOM-based cross-site scripting
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.
What can XSS be used for?
An attacker who exploits a cross-site scripting vulnerability is typically able to:
Introduction to XSS Attack
Cross Site Scripting attack is a malicious code injection, which will be executed in the victim’s browser. Malicious script can be saved on the web server and executed every time when the user calls the appropriate functionality. It can also be performed with the other methods – without any saved script in the web server.
Recommended Tools
Acunetix is a web application security scanner that gives you a 360-degree view of the organization’s security. This end-to-end web security scanner can identify over 7000 vulnerabilities like XSS and misconfigurations. It has capabilities for scanning all pages, web apps, complex web applications, etc.
How is XSS Being Performed?
Cross Site Scripting attack means sending and injecting malicious code or script. Malicious code is usually written with client-side programming languages such as Javascript, HTML, VBScript, Flash, etc. However, Javascript and HTML are mostly used to perform this attack.
Types of Cross Site Scripting Attacks
The prime purpose of performing XSS attack is to steal other person’s identity. As mentioned, it may be cookies, session tokens, etc. XSS also may be used to display faked pages or forms for the victim. However, this attack can be performed in several ways.
How to Test Against XSS?
Firstly, in order to test against XSS attack, black box testing can be performed.
XSS Testing Tools
As Cross Site Scripting attack is one of the most popular risky attacks, there are a plenty of tools to test it automatically. We can find various scanners to check for possible XSS attack vulnerabilities – like, Nesus and Nikto. Both of which are considered as quite reliable.
Comparison with Other Attacks
XSS is considered to be one of the riskiest attacks, as its main purpose is to steal the website’s or system’s user identities. Also, XSS attack can be performed with different client-side languages like Javascript, HTML, VBScript, Flash, etc. And this makes it more harmful and widespread than the other possible attacks.
Overview
- Cross-Site Scripting (XSS) attacks are a type of injection, in whichmalicious scripts are injected into otherwise benign and trustedwebsites. XSS attacks occur when an attacker uses a web application tosend malicious code, generally in the form of a browser side script, toa different end user. Flaws that allow these attacks to succeed arequite wide...
Related Security Activities
- How to Avoid Cross-site scripting Vulnerabilities
1. XSS (Cross Site Scripting) Prevention Cheat Sheet 2. DOM based XSS Prevention Cheat Sheet 3. OWASP Development Guide article on Data Validation 4. OWASP Development Guide article on Phishing - How to Review Code for Cross-site scripting Vulnerabilities
See the OWASP Code Review Guide.
Description
- Cross-Site Scripting (XSS) attacks occur when: 1. Data enters a Web application through an untrusted source, most frequently a web request. 2. The data is included in dynamic content that is sent to a web user without being validated for malicious content. The malicious content sent to the web browser often takes the form of asegment of JavaScript, but may also include HTML, Fl…
Examples
- Cross-site scripting attacks may occur anywhere that possibly malicioususers are allowed to post unregulated material to a trusted website forthe consumption of other valid users. The most common example can be found in bulletin-board websites whichprovide web based mailing list-style functionality.
Related Attacks
Related Vulnerabilities
- Improper Data Validation
- Types of Cross-Site Scripting
- OWASP Development Guide article on Data Validation
- OWASP Development Guide article on Phishing
References
- OWASP’s XSS (Cross Site Scripting) Prevention Cheat Sheet
- Testing_for_Reflected_Cross_site_scripting
- Testing_for_Stored_Cross_site_scripting
- Testing_for_DOM-based_Cross_site_scripting