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An XSS attack uses the server as a vector to present malicious content back to a client, either instantly from the request a reflected attack , or delayed though storage and retrieval a stored attack. An XSS attack exploits a weakness in the server's production of a page that allows request data to show up in raw form in the response.
The page is only reflecting back what was submitted in a request Here's a quick example. Calling the same page with something more malicious can be used to alter the page or user experience substantially.
Instead of just saying, "Hi, Rumplestiltskin", this URL would also cause the page to pop up an alert message that says, "Boo! That is, of course, a simplistic example. One could provide a sophisticated script that captures keystrokes or asks for a name and password to be verified, or clears the screen and entirely rewrites the page with shock content.
It would still look like it came from example. So, if the page is just spitting back content provided by the person requesting it, and you're requesting that page, then how does a hacker infect your request?
Usually, this is accomplished by providing a link, either on a web page or sent to you by e-mail, or in a URL-shortened request, so it's difficult to see the mess in the URL. A server with an exploitable XSS vulnerability does not run any malicious code itself-- its programming remains unaltered-- but it can be made to serve malicious content to clients.
A simple example would be a URL parameter that is written to the page. You could change the URL parameter to contain script tags. Another example is a comment system. It's better to think of the script as being injected into the middle of the conversation between the badly coded web page and the client's web browser.
It's not actually injected into the web page's code; but rather into the stream of data going to the client's web browser. Learn more. What is cross site scripting? Ask Question. Asked 7 years, 2 months ago. Active 4 months ago. Viewed 10k times. Peter Mortensen Victor Victor 14k 57 57 gold badges silver badges bronze badges.
Active Oldest Votes. I had the wrong idea that inside a company intranet, when you try to access a website that is in a different domain within the same company only then XSS problems occur. Bit it seems that XSS can occur all the time.
Your new understanding is correct. You're describing a valid danger, though. XSS initially just affects the page you're accessing, but the new content you inject can redirect you anywhere-- and is especially dangerous when that place is somewhere you've already authenticated into.
SurajJain You're describing a "stored attack" vs. Both are XSS, and in both cases, the server is used as a vector to deliver a malicious payload to a remote client, but the server itself isn't ever made to run any instructions it wasn't designed to run. That attacker doesn't need access to the source code. These are simple examples. There's a lot more to it and a lot of different types of XSS attacks. Jason P Jason P There are two types of XSS attacks: Non-persistent: This would be a specially crafted URL that embeds a script as one of the parameters to the target page.
The nasty URL can be sent out in an email with the intent of tricking the recipient into clicking it. The target page mishandles the parameter and unintentionally sends code to the client's machine that was passed in originally through the URL string. Persistent: This attack uses a page on a site that saves form data to the database without handling the input data properly. A malicious user can embed a nasty script as part of a typical data field like Last Name that is run on the client's web browser unknowingly.
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DOM Based XSS
To be used for demonstrating attacks. Moreover authentication and authorization for users is implemented. Xssing is a simple semantic analysis based on the location of the vulnerability, to determine the existence of the vulnerability, and use chromium to verify that xss is existed. Add a description, image, and links to the xss-attacks topic page so that developers can more easily learn about it.
XSS (Cross-Site Scripting) – Overview and Contexts