How to Prevent XSS

XSS or cross-site scripting is a type of injection attack in which an attacker makes use of the XSS to send malicious script to any user. Such types of attacks are more common in web-based applications. This is possible for the attackers due to some of the vulnerabilities in the computer security. Cross-site scripting can be prevented by using some of the security methods while coding, and changing some settings in your system. Here are a few tips that will help you know how to prevent XSS.

When such malicious script is sent to your system by the attacker, it can access cookies, session tokens and any other important information retained in your browser and used by the site. Therefore, you may give access to your credit card passwords and other important passwords and information to the attacker. Some of these scripts are even capable of changing the content of the available HTML page in your browser.

How to identify the risk:

It is very difficult to trace this risk. You need to check in all the HTML pages of the web page to see whether in any way that can return the input in the HTTP request to the HTML output. Performing the security check on the code, you can identify the risk. This can be done if you are aware of the programming skills. You need to know the HTML tags.

There are also some tools, which will help you scan for the risk within your system. You can install these tools in your system and perform security checks periodically. These methods will only allow you to identify the vulnerability. If you want to eliminate or prevent the risk of XSS or cross-site scripting, you need to take certain precautionary measures.

Tips to prevent XSS:

What programmers should do?

Cross-site scripting is a matter of concern in case of web based applications, so web developers need to take extra precautions while designing and coding web based applications. Here are some methods that a web developer needs to follow to prevent XSS or cross-site scripting.

Proper validation methods:

  • Proper validation methods should be used while designing the code.
  • Programmers should make sure that while the user is logging in or submitting any crucial passwords or information to the web site, input should be sent to the user only after validating them for any malicious code within the script.

Look for the holes:

  • Some of the web site use HTTPS while transferring data. Such websites cannot be trusted completely as the attacker can still send malicious script through the XSS holes in the application.
  • You should use some other methods or program in such a way that no holes are left in your script.

Convert non-alphanumeric characters into HTML characters:

  • Programming should be done in such a manner that all the non-alphanumeric characters are converted into HTML characters before displaying the user inputs in the search engines and forums.
  • Doing this passwords and other important data can be protected from attackers.

Authenticate scripts:

  • When a user requests or sends some script through his browser, the website should be able to check that the sent script is really an authenticated script and then have access to the information.
  • Developer has to develop some signing scripts that are unique and standard and contain private and public keys. These scripts will allow the website to check for the authenticity.

Filter ‘meta’ characters:

  • Filtering Meta characters is also one of the methods that should be adapted while designing the code.
  • When a user enters input to have access to some information, the code should filter the Meta characters from the input and check for the authentication.
  • This will also help in preventing the data from being hacked by the attacker.

Rigorous testing:

  • Testing at each and every stage while development is essential. This will help in eliminating XSS holes that are present in the application.
  • Follow proper development life cycle and simultaneous testing life cycle, such that the applications is designed and tested properly before the release.
  • Manual as well as automation testing using proper tools is essential to release a product with minimum bugs and holes in it.

What users can do?

User also has to take some precautionary measures while requesting crucial information from a site.

  • Installing a web application firewall in your system, you can identify which web sites are vulnerable to the cross-site scripting attacks.
  • These attacks are done through the scripting language. Therefore, disable scripting, whenever it is not required.
  • Turn off the HTTP trace support on all the web browsers installed in your system. This will also help you in preventing the script attacks.
  • If you are accessing any important information or sending any important information, perform such tasks directly by visiting the companies’ website. Do not navigate to that website through any other third-party sites.
  • When you are visiting any security sensitive pages, do not follow any links that take you to other websites unless you trust them.
  • Never click on the links provided on the sites if you are accessing the current site for an important task. These links may contain malicious code.
  • Do not follow any forums. They are vulnerable of the cross-site scripting largely.

Following the tips given above, you can easily prevent cross-site scripting or XSS.


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