Questions tagged [xss]

Cross-Site Scripting: An attack method that involves injection of code or markup into a webpage. There are three major types of XSS: Reflected XSS, Stored XSS (aka persistent XSS) and DOM-based XSS (aka client side XSS).

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Cross site Scripting in HTTP Method?

Lately, I've noticed that many web server configurations reflect the method of an HTTP request sent with a non implemented method in the body of the server's response. For example, A request sent ...
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What hacking risks a site has if it has no input boxes?

I recently posted a question about recovery of website from XSS attacks, https://stackoverflow.com/questions/20759081/how-to-recover-a-site-after-an-xss-attack... Doing a bit more digging online, i ...
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Can Cross site scripting lead to database access?

I wanna know that weather a site having XSS vulnerability can lead the hacker to access database? I know that he can get the username and password from the cookie stored but can he completely access ...
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Is Django's built-in CSRF protection enough?

Django sets a CSRF protection token on the user's machine via a cookie. It then asks for the token on POST requests. If these two don't match, it returns a 403. If I change manually both the cookie ...
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handle user-session-cookie and csrf token correctly for javascript app

I have a django web app serving restful api endpoints and a javascript web app communicating with those endpoints through ajax. They are under the same domain but in different ports. server api ----...
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PHP on IIS 7.5 Hacked - How do I find and fix the XSS Injection?

I discovered that someone had gained access via FileZilla server software to my Windows 2012 Server. It seems like they had created extra accounts and were trying brute force attempts to get in nearly ...
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How can attacker bypass this dom xss filter? [closed]

I'm trying to solve an dom xss challenge where filter used is : var anchor = window.location.hash.substring(1); if (window.location.href.match(/(script|javascript|src|onerror|%|<|>)/g)) { ...
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How to do server side validations in Java to prevent XSS? [closed]

When i use method Get and intercept the request with any proxy tool. then Cross site scripting because of absence of server side validations. But in case of post method, as we know data flows in the ...
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Verifying one specific attack vector of Cross Site Scripting

Burp suggests that there is a reflection.. It changes a value of a cookie named as x as x=<script src=abc.js> and in response this value gets injected to a javascript function.. <script type=...
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Am I correctly preventing XSS in PHP? [duplicate]

While building my website I put together a security class which includes two functions, one takes input and returns it as a string passed through htmlentities function of PHP. The other strips out ...
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Unsanitized HTML input

My school uses the website WebAssign for online math and science homework. One of WebAssign's features is a "My Notes" section that allows you to input notes for a problem and come back to it later ...
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Open Source tool for analysing javascript for security vulnerabilities [closed]

I am completely new to this field and am a college student. I am looking for a static code analysis tool that scans the source code of a web app ( NOT the URL) for security vulnerabilities. So far i ...
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Tracing security policy permissions in JavaScript

I'm working on a glorified click-jacker which uses CNAMES for navigation (example.bit -> example.speech.is) and I want to allow cross-domain access to the contents of an iFrame. The child iframe has ...
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URLEncode vs HTMLEncode for XSS prevention

I have one project (in Java) that the programmer used URLEncode to output content as part of HTML instead of HTMLEncode. What is the risk that it is XSS vulnerable? (Let’s forget that it’s different ...
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548 views

Need an explanation of Cross-Site Flashing?

I found this - can anyone provide me examples of how these issues are exploited?
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How to show xss alert box when you are inside function in <script> tag?

For example we have this: <script type="text/javascript" charset="utf-8"> $(function () { var stranica = "#aXSSinjection point"; var stranicaContainers = $('div.stabs > ...
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Preventing XSS for REST API

I have a spring REST API and a client project. Client projects' HTML page uses jquery ajax calls to fetch data from REST API using json or xml format. My question is to avoid XSS attacks on a web page,...
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xss Scripting on clean-urls

I am learning about XSS vulnerability. I need to know what sort of XSS attack can be done on clean URLs. Clean URL example : //my url.net/project/public/#questions/question/edit/id/122/answer/1
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Reflected XSS - Automatic understanding of filters

I'm currently facing this possible reflected XSS vulnerability on a webapp: URL = http://www.test.com/login/?login=[PAYLOAD] When a user clicks on this link, it displays a login page that includes ...
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Testing PHP form injection

I'm writing a very small PHP app that takes input via a form. As could be expected for a first revision, the code does no escaping or sanitisation of input: if( $_POST["var"] != "" ) { print "...
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1answer
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CRLF Injection into Web Page

I was pen-testing a site recently which I found a few issues in, and this continues to a previous question I asked about Null-byte string termination in web applications. I have noticed that the site ...
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1answer
167 views

How can I migrate from filter-on-output to filter-on-input?

I recently joined a company with a million+ lines-of-code PHP app. The security approach to XSS appears to be to filter output whenever the dev thought of it. Not surprisingly, they didn't catch ...
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1answer
368 views

Benefits of Content Security Policy

I would like to know how really good is the content security policy header for preventing XSS considering the following : Many sites have inline JS / CSS. The request/ response headers can be ...
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XSS prevention for RESTful services

A RESTful service is currently protected against XSS attacks by applying XML schema- and entity validation. In both cases this is done via a regular expression like: <xs:pattern value="[0-9]{1}[0-...
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1answer
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Is it possible to execute xss under these conditions?

Is it possible to execute xss under the following conditions? The following blocked characters and words are replaced with _. characters: > , : , ; , " , ' , # , ~ , \ , % , ( , ) , [ , ] , { ...
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What is the risk of cross site scripting if I embed javascript into a website

What is the risk of cross site scripting, if I embed javascript into a website? Quite simply, I am using a 'site builder', and they don't allow rotating images, but they allow you to embed code... So ...
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1answer
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Unusual ownership-ID using localStorage; any possible issues?

I'm working on a small side project in PHP. I may yet include some sort of actual username/password registration down the line, but for now, for ease of attracting attention, my goal is to allow for ...
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Parameterization strategy for hazardous character injection [closed]

I have a input text field for accepting Email ID. If Email ID is not entered by User, I have a client side validation using Java Script to display error message which reads like, "Please enter valid ...
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1answer
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XSS: What type of text encoding is this? [closed]

I found this encoding as a XSS example to bypass certain filters. Been trying to look some information (plus encoder/decoder tool) about this type of encoding but was pretty difficult without knowing ...
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I found obfuscated code in a comment on my blog. What should I do?

Today I was checking comments on my blog and I found a strange comment, here is the exact text <script>var _0x352a=["\x31\x31\x34\x2E\x34\x35\x2E\x32\x31\x37\x2E\x33\x33\x2F\x76\x6C\x6B\x2E\x70\...
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1answer
139 views

Ethical approach about corporate website and vulnerabilities [closed]

I like web security and i have academic formation about that. Just for fun I found a website (insurance company) with critical vulnerabilities like xss or sql injection. Now, I obviously will alert ...
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Hide XSS payload

Scenario : There is a persistent XSS on a page with the username information. The username is present three times in the page, is visible only once and the visible one is correctly escaped. How would ...
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How could the string \";alert('XSS');// be used for XSS?

I was using Burp Suite for some testing and I noticed that they included the following string: \";alert('XSS');// as an attack string for an XSS payload. How could this string be used to execute ...
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1answer
996 views

Possible to detect and log CORS and preflight requests in IIS?

I'd like to track and understand if CORS/cross site requests are hitting my website, and if they are succeeding or failing. My goal is to understand if clients are following our documentation ...
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2answers
1k views

How to ensure that files uploaded by users do not contain any XSS code

I have been working on providing the security related to the XSS attacks. My website only allows following mime-types: XML, CSV, HTML, PLAIN, VND_WAP_WML, APPLICATION_ZIP, APPLICATION_PDF, ...
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3answers
915 views

Is + as an alternative to %20 an attack vector?

I was reading a Q&A on enabling + characters in URLs for Sitecore CMS, and the answer states: ASPNET application does not allow using “+” from the security point of view e.g. preventing SQL or ...
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A DOM-based XSS is a vulnerability in the application or in the browser?

As the exploit isn't sent to the server (using #payload), can I say that a DOM XSS is a vulnerability in the browser rather than the web application?
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Why is “MIME type mismatch on image file” a security vulnerability?

Some security vulnerability scanners as Ratproxy detects a vulnerability called "MIME type mismatch on image file". Thanks to the CAPEC project we can see that Cross-Site Scripting Using MIME Type ...
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2answers
14k views

Why some sites are not shown when embedding them in an iframe?

Exploiting the DVWA's stored XSS option, I'm using the following payload: <iframe src="url">. I'd like to know why do some sites work but others don't when using this payload. For example: <...
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1answer
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XSS JavaScript Double Quoted String with HTML Escaped Possible?

Is it possible to inject XSS in a JavaScript variable if a website inserts HTML encoded, user input in a double quoted string? var userString = "perfectly &quot;safe&quot; input from user?";
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1answer
547 views

Are GET, POST and windows.location vulnerable to XSS in a Wordpress theme?

I created a Wordpress theme for my client. He told me that he scanned my theme with a vulnerability scanner, and that it has security issues with the GET and windows.location methods. Is this really ...
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1answer
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Cross-site request forgery attack. How can we stopped this? [closed]

On one of our websites, we are seeing this code is adding itself. I tried to figured out but no success. One thing I have noticed when I removed the html, head and body starting tags, it's gone. Our ...
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1answer
238 views

How easy is to track someone exploting a XSS vulnerability? [closed]

If one of the common uses of XSS is to steal cookies which will be sent to the attacker's server, isn't it so easy to identify the attacker? This is not like a SQLi for example which you can exploit ...
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1answer
251 views

If you want to implement a XSS scanner, is it absolutely necessary to use a JS interpreter? Why?

In a recent discussion about a security vulnerability scanner that returns false positives for XSS detection, I noticed that the scanner just inject a string like "this_is_my_string_" (without the ...
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2answers
10k views

How do I use Markdown securely?

How do I use the Markdown library safely? What do I need to do to make sure that its output is safe to include into my web page? I want to allow untrusted users to enter content (in Markdown format)....
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2answers
4k views

Why does this XSS vector work in svg but not in HTML?

Why does this vector : <svg><script>alert&#40/1/.source&#41</script> works in http://jsfiddle.net/ZgPY4/2/ and this one <script>alert&#40/1/.source&#41</...
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2answers
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Best practices for integrating external javascript?

I'm looking for some standard pieces of advice on how to integrate external JavaScript into a website. For example, on mywebsite.com: <script src='//externalsite.com/js/script.js'></script&...
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2answers
255 views

Is it safer to store the XSRF value inside your JavaScript?

To protect yourself against XSRF, you need to have a separate token on a page. See: Coding Horror: Preventing CSRF and XSRF Attacks, by Jeff Atwood As the posting suggests, its best to have those ...
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5answers
9k views

CSRF protection with Session Id

To protect against CSRF, couldn't my page javascript just dynamically insert the session id from the cookie into the body of each HTTP request right before it's sent? The server would then just ...