What’s the Difference Between Reflected and Stored Cross Site Scripting?
When it comes to web security, cross-site scripting (XSS) is a common vulnerability that developers need to be aware of. XSS occurs when an attacker injects malicious scripts into a website, which are then executed by the victim’s browser. This can lead to various security issues, such as data theft, session hijacking, or even complete website compromise.
Reflected XSS
Reflected XSS, also known as non-persistent XSS, is a type of attack where the injected malicious script is embedded within a URL or a form input. When the victim clicks on the manipulated link or submits the compromised form, the script gets executed in their browser.
The key characteristic of reflected XSS is that the injected script is not permanently stored on the Targeted website’s server. Instead, it is reflected back to the victim as part of the server’s response. The attacker usually tricks the victim into clicking on a specially crafted link that contains the malicious payload.
How Does Reflected XSS Work?
The process of a typical reflected XSS attack can be broken down into three steps:
- The attacker crafts a URL or form input that contains a script payload.
- The victim interacts with this URL or form by clicking on it or submitting it.
- The server processes this input and reflects back the script payload in its response to the victim’s browser.
This type of attack is often used in phishing campaigns where attackers create convincing URLs that appear legitimate to deceive victims into visiting them. Once victims click on these URLs, their browsers execute the injected script, giving attackers control over their sessions or stealing sensitive information like login credentials.
Stored XSS
Stored XSS, also known as persistent or second-order XSS, is a more dangerous variant of XSS. In this type of attack, the malicious script is permanently stored on the Target website’s server. Whenever the victim accesses the compromised page, the script gets executed in their browser.
The key difference between stored and reflected XSS is that in stored XSS, the payload is not reflected back directly to the victim but rather served from the server itself. This makes it possible for attackers to inject scripts that can affect multiple users who access the compromised page.
How Does Stored XSS Work?
The process of a typical stored XSS attack can be summarized as follows:
- The attacker finds an input field on a vulnerable website where user-generated content is stored without proper sanitization or validation.
- The attacker injects a malicious script into this input field.
- Whenever any user (including the victim) visits the compromised page, their browser fetches and executes the stored script from the server.
Stored XSS attacks can have severe consequences as they can impact multiple users and persist over time. Attackers can exploit these vulnerabilities to distribute malware, steal sensitive data from users, or even take control of entire websites.
Differences Between Reflected and Stored XSS
To summarize, here are some key differences between reflected and stored XSS:
- Persistence: Reflected XSS attacks are non-persistent and rely on tricking victims into interacting with specially crafted URLs or forms. Stored XSS attacks are persistent and affect all users who access the compromised page.
- Storage Location: In reflected XSS, the malicious script is not stored on the server and is instead reflected back in the server’s response.
In stored XSS, the script is permanently stored on the server and served to users whenever they visit the compromised page.
- Impact: Reflected XSS attacks can only affect victims who interact with the manipulated URLs or forms. Stored XSS attacks can impact multiple users and persist over time.
It’s crucial for developers to understand these differences and implement proper security measures to prevent both reflected and stored XSS vulnerabilities. This includes input validation, output encoding, and adopting secure coding practices to minimize the risk of these attacks.
In conclusion, while both reflected and stored XSS are dangerous web vulnerabilities, their mechanisms and impacts differ significantly. By being aware of these differences, developers can take proactive steps to safeguard their websites from potential exploitation.