How to detect Cross Site Scripting Issues (XXS)

Today we take a look at cross-site scripting, explaining what it is, the dangers it presents, and how to find and test for vulnerabilities, all in a language that any business owner can understand.

What is cross-site scripting?

Cross-site scripting is the most well-known web app vulnerability that can lead to your website being hacked.

According to the OWASP:  XSS flaws occur whenever an application includes untrusted data in a new web page without proper validation or escaping, or updates an existing web page with user-supplied data using a browser API that can create HTML or JavaScript. XSS allows attackers to execute scripts in the victim’s browser, which can hijack user sessions, deface web sites, or redirect the user to malicious sites.

In simple terms, it means that the user might click on a link in an email, message, or forum and visit a genuine website. The page might request the user’s login ID and password. When these are entered, malicious code in the original link works invisibly in the background to capture the login ID. The ID and password are collected for the hacker’s use. From this point, the hacker can send malicious code to the user’s computer and use web browsers or email apps with the same security privileges. The hacker can install malware or browse history files.

 

Example:

How is Cross site scripting dangerous?

XXS can be leveraged by hackers and cyber attackers to gain access to the personal information of anyone that falls victim to a phishing scam. Phishing occurs when an attacker masquerades as a trusted entity, with the unsuspecting victim opening an email, text message, or instant message.  

These details can be used to:

  • 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 website.
  • Inject Trojan functionality into the website.

How to find and test for XXS vulnerabilities 

Cross-site scripting is the most common software security vulnerability, yet it is easy to find and fix. Cross site scripting vulnerabilities, security misconfiguration, and insecure deserialisation can be found during penetration testing. Pen testing by Omnicyber Security is an effective way to test for weaknesses and take remedial action to lower the risks of a successful cyber attack. 

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