What are the different types of XSS attacks and how do they differ from each other?
Cross-site scripting (XSS) is a common vulnerability in web applications that allows attackers to inject malicious scripts into web pages viewed by other users. XSS attacks can have various types and understanding these types is important for effective web application security. In this answer, we will explore the different types of XSS attacks and how they differ from each other.
1. Stored XSS:
Stored XSS, also known as persistent XSS, occurs when an attacker injects malicious code that is permanently stored on the target server. This code is then served to users whenever they access the affected page. The injected code can execute arbitrary JavaScript, leading to unauthorized actions or theft of sensitive data. An example of stored XSS is when an attacker posts a malicious script as a comment on a blog, and any user viewing that comment becomes a victim of the attack.
2. Reflected XSS:
Reflected XSS, also known as non-persistent XSS, involves the injection of malicious code that is not stored on the target server but is instead embedded within a URL or a form input. When the user interacts with the vulnerable website, the injected code is reflected back in the server's response, executing in the victim's browser. An example of reflected XSS is when an attacker crafts a malicious URL containing a script, and a user clicks on that URL, triggering the execution of the script.
3. DOM-based XSS:
DOM-based XSS occurs when the vulnerability lies within the Document Object Model (DOM) of a web page. In this type of attack, the malicious code is not directly injected into the server's response or stored on the server. Instead, it is injected into the client-side script, altering the behavior of the webpage. The injected code manipulates the DOM, leading to unintended actions or data exposure. An example of DOM-based XSS is when an attacker manipulates the URL fragment identifier (#) to execute a script on a vulnerable webpage.
4. Blind XSS:
Blind XSS, also known as stored DOM XSS or server-side XSS, is a type of attack where the injected code is stored on the server and executed when a specific event occurs. However, the attacker does not directly observe the impact of the attack. Instead, they rely on a third party, such as an administrator or another user, to trigger the execution of the injected code. Blind XSS can be more challenging to detect and mitigate since the attacker's interaction is indirect.
5. Self-XSS:
Self-XSS, also known as self-inflicted XSS, relies on social engineering techniques to trick users into executing malicious code on their own browser. Attackers often exploit users' curiosity or desire for personalization by enticing them to copy and paste malicious code into their browser's developer console. Once executed, the code can perform unauthorized actions or steal sensitive information. Self-XSS attacks can be mitigated through user education and awareness.
XSS attacks can manifest in various forms, including stored XSS, reflected XSS, DOM-based XSS, blind XSS, and self-XSS. Each type has its own characteristics and methods of exploitation. Understanding these types is essential for developing effective defenses against XSS vulnerabilities.
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