Free and Online Generic XSS Scanner

Online XSS Scanner Tool for HTTP GET and POST method

Using unsanitized data allows malicious scripts to be executed on the end user's machine, which can lead to cookie theft, session hijacking, and other types of information disclosure that could compromise the end-user's privacy.

With this free online XSS scanner you can easily scan your webpage for XSS vulnerabilities. This tool uses HTTP GET and POST methods to scan your url. If query params exist we parse and scan for each params, if not we add our payloads to the end of the URL.

Sample assets for Online XSS Scanner

For example, this XSS scanner tool parses search and page parameters and test for xss vulnerability for a url such:

https://s4e.io/?search=xss&page=1

We add our payload to end of the URL for a url such:

https://s4e.io/blog/top-8-open-source-web-crawlers

If you want to scan for a post parameter using this tool, we parse any form inputs in the page and test for XSS.

By analyzing your web page, we find the forms that communicate with the POST request and look for XSS vulnerabilities in these form parameters.

Types of XSS Vulnerability

There are three main types of XSS vulnerabilities which are :

• Reflected Cross-Site Scripting (XSS)
• Stored Cross-Site Scripting (XSS)
• DOM-Based Cross-Site Scripting (XSS)

Reflected Cross-Site Scripting (XSS) is the most common type of vulnerability and occurs when an attacker injects malicious code into an HTTP request and the response is reflected back to the user. This code is then executed by the victim's browser.

Stored Cross-Site Scripting (XSS) is a less common type of vulnerability that occurs when data is stored in an unsafe way on the server. This data can then be accessed and manipulated by attackers using a variety of methods.

Finally, DOM-Based Cross-Site Scripting (XSS) is a type of vulnerability that occurs when an attacker exploits a hole in the client side code. The client side scripts expose the vulnerable page to XSS attacks, and this is referred to as "DOM-based" because of the fact that it typically runs in the client browser due to an interaction with JavaScript code.

Lets move on and learn more about this vulnerability.

There are several different types of attacks that can be launched using an XSS vulnerability.

With S4E online XSS scanner you can scan your webpage for all types of XSS vulnerabilities.

What is the Impact of Cross-Site Scripting Vulnerability?

These include, but are not limited to, the following:

1. Cookie theft – The attacker tricks the user into clicking on a link that injects malicious code into their browser. This code then steals the user's cookies, which can be used to hijack their session or gain access to their account.
2. Session hijacking – The attacker tricks the user into clicking on a link that injects malicious code into their browser. This code then takes over the user's current session, allowing the attacker to access their account or data. (In some app sessions can be created without cookies)
3. Phishing attacks – The attacker tricks the user into clicking on a link that injects malicious code into the user's browser. This code then allows them to display a false login page that can steal their usernames, passwords and other account information when they try to login.
4. Defacing web pages at client side – The attacker tricks the user into clicking on a link that injects malicious code into the user's browser. This code then defaces the webpage and inserts links or banners in place of legitimate content.
5. Malicious iFrames – If an XSS vulnerability exists in a website that uses an HTML iFrame, the attacker could also steal the cookies and hijack sessions of users who visit it.
6. Malware injection – The attacker tricks the user into clicking on a link that injects malicious code into their browser, which then downloads malware onto their device such as keyloggers and ransomware.
7. RATs (Remote Access Tools) – The attacker tricks the user into clicking on a link that injects malicious code into their browser, which then downloads RATs onto their device to take full control of it from a remote location.
8. Botnets – The attacker tricks multiple users into clicking on a link that injects malicious code into their browsers, which makes them unknowing participants in a botnet attack. This can lead to large amounts of distributed denial-of-service attacks, spamming and other illicit activities.
9. Browser lockers - A browser locker aims at "locking" your web browser by scrambling all the data you have entered including usernames and passwords thus preventing you from logging back into your account unless you pay money.

The consequences of an XSS vulnerability on a website include, but are not limited to the following:

What are the risk of XSS Vulnerabilities?

1. Reputational damage – A successful XSS attack can result in negative publicity for the affected website or brand. For example, if users receive defacement alerts on websites they visit or start receiving phishing emails about their accounts, their trust in that brand is likely to decrease substantially. This will inevitably hurt that site's reputation and lead to lost sales.
2. Loss of revenue – If an attacker successfully gains access to user accounts through an XSS vulnerability on a commercially-used website, they could steal personal information about these users which could be used to make fraudulent purchases online.
3. Financial losses – If an attacker successfully gains access to user accounts through XSS vulnerabilities on websites used for banking, they could intercept login details and use this information to transfer funds out of the victim's account.
4. Increased technical costs – In order to fix XSS vulnerabilities, webmasters have to investigate how these affect their website and implement multiple layers of security that can prevent future attacks from being successful. If an XSS scanner finds a vulnerability on a webpage, more investigation must be made to see if it’s exploited or not which can take much more time.
5. Data loss from stolen cookies – If an attacker successfully gains access to a user's account through XSS vulnerabilities, they can use these vulnerabilities to access all sensitive information including saved passwords and cached usernames and passwords so long as the victim is logged into their device/browser while browsing the affected website.
6. Attack vector for future exploits – The more security flaws a system has, the more likely it will be targeted by attackers who are looking to exploit these weaknesses in order to gain full control over the system.
7. Personal Identification Theft – Attackers can gain full access to victims' online identities by stealing their social media credentials. This gives them the ability to hijack individual profiles as well as start sending malicious emails or phishing attempts on behalf of the affected users.
8. Blackmailing – Attackers can use obtained login credentials to compromise an individual's online reputation by publishing malicious content under their name in order to blackmail them into paying for damage control services.

How to prevent from XSS attack? - Solution Advices

There are a number of prevention tips that can be followed in order to reduce the risk of being vulnerable to XSS attacks. These include:

1. Input Validation and Output Escaping:

Ensure that all user input is properly validated and escaped before being processed by the application. This will help to prevent any malicious code from being executed.

Sample pseudo-code:

$name = $_REQUEST[‘name’];
echo "Greeting $name, nice to meet you!";

Vulnerable Code	Secure Code
$_REQUEST[‘name’]	convert_to_htmlentities(_REQUEST[‘name’]

2. Testing and data normalization:

Regularly test applications for vulnerabilities and ensure that all data is properly normalized before being used in database queries or rendered on the page. This will help to identify any potential script injection points.

You can use all of our tools for free including xss scanner or our automated vulnerability scanning services to be automated.

3. XSS Prevention Rules:

Implementing a set of XSS prevention rules can help to protect against most common code injection attacks. For example, disallowing the use of "<", ">" and '/' characters in user input fields will help to stop cross site scripting issues. Be aware that : use whitelist if you can, using a blacklist for characters may be bypassed.

4. HTTPOnly Cookies:

Using the 'HttpOnly' flag when setting cookies within an application does not prevent XSS attack but can help to decrease impact of cross site scripting attacks as these types of scripts cannot interact with HTTP cookies and therefore cannot extract their values and compromise other users in the process.

5. Secure Coding Practices:

Implementing secure coding practices can help to avoid common vulnerabilities such as XSS - cross site scripting by ensuring that the code is properly written without any unnecessary functionality.

Other Methods to Check For XSS Vulnerability

• XSStrike Tool
• Xsser Tool
• PwnXSS Tool

Summary

Using a XSS scanner is important as it can help to identify any potential XSS vulnerability in an application. In addition, using an automated vulnerability scanner Continuous Security can help to ensure that applications are properly tested for all vulnerabilities on a regular basis.

This includes Cross-site scripting (XSS) attacks which exploit vulnerabilities in the site code and uses them to inject HTML-based code into a visitor’s session with the website.