6.15. Types of Information Security Threats: Cross-Site Scripting Attacks
In an increasingly digitized world, information security has become a crucial aspect for companies and individuals. Among the various existing threats, Cross-Site Scripting (XSS) attacks are particularly dangerous and prevalent. This type of attack exploits vulnerabilities in web applications to inject malicious scripts into pages viewed by other users.
What is Cross-Site Scripting (XSS)?
Cross-Site Scripting is a type of attack that occurs when an attacker manages to insert a malicious script into a web page, which will be executed in the user's browser when accessing the page. This script can be used to steal sensitive information such as login credentials, credit card details, and more. XSS is an injection-based attack, similar to the SQL injection attack, but it takes place on the client side, i.e. on the user's browser rather than on the application server.
Types of XSS Attacks
There are three main types of XSS attacks: stored, reflected, and DOM-based.
Stored XSS
Stored XSS, also known as persistent, occurs when the malicious script is permanently stored on the target server. The script is then sent to the user's browser each time the page is accessed. This is the most dangerous type of XSS as the attack occurs every time the infected page is accessed.
XSS Reflected
Reflected XSS, also known as non-persistent, occurs when malicious script is embedded in a URL. When the user clicks on the URL, the script is sent to the server, which reflects it back to the user's browser. This type of attack usually occurs in conjunction with a phishing attack, where the attacker tricks the user into clicking on the malicious URL.
DOM Based XSS
DOM-based XSS occurs when malicious script manipulates the Document Object Model (DOM) structure of a web page. Unlike other types of XSS, the DOM-based attack does not send the malicious script to the server, but executes it directly in the user's browser.
How to Protect Against XSS Attacks
There are several measures you can take to protect against XSS attacks. The first line of defense is input validation. Web applications must validate all incoming input to ensure that it does not contain malicious scripts. In addition, applications should use output encoding to ensure that any script inserted into the page is treated as text and not executed.
Another important measure is the implementation of content security policies (CSP), which restrict the scripts that can be executed on a page. Additionally, applications should use secure cookies and implement the HttpOnly attribute to protect against cookie theft.
Finally, it's essential to keep web applications up-to-date and apply security patches as they become available. Many XSS attacks exploit known vulnerabilities in outdated software.
In conclusion, Cross-Site Scripting attacks are a serious threat to information security. However, with awareness and implementation of good security practices, it is possible to protect against these attacks and keep information safe.
