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), DOM-based XSS (aka client side XSS).

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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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PHP functions for preventing XSS

Is there a proven library with functions for preventing XSS attacks? Many people don't realise that htmlspecialchars is not enough to prevent XSS attacks. There are various contexts that need their ...
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3answers
874 views

How serious are XSS attacks

A website I visit allows this kind of attack, to be implemented with GET in the URL <SCRIPT SRC=http://ha.ckers.org/xss.js></SCRIPT> Along with many others on this page: ...
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JavaScript written only with brackets?

I once saw JavaScript code which was only written as multiple brackets (). Does anybody remember this kind of code? There was also an online converter to convert "normal" JS into this style of code. I ...
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1answer
336 views

Has The IE8 XSS Filter XSS Flaw Been Fixed?

You may remember: X-XSS-Protection: 0 http://hackademix.net/2009/11/21/ies-xss-filter-creates-xss-vulnerabilities/ Has this been fixed in IE8? IE9? IE10? Is it implemented in IE7?
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Does the practice of blocking an off-site “Referer:” HTTP requests improve website security?

Is there any benefit for a security-paranoid website to disallow HTTP requests that have a Referer: from 3rd party sites? The pitch is that if such a HTTP request were to come in, then certain XSS ...
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5answers
389 views

Is it possible to see if a script on a website steals session cookies?

I'm looking as some web analytics solutions, I know it sounds paranoid. but cookie-based web analytics need for you to paste their JavaScript code on your web-site. I don't like the idea too much of ...
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Are PHP Sessions based on cookies or a cookie-IP pair?

I have a PHP website and my question is: If someone manages to steal my users' cookies via an XSS attack, is it enough for him to be identified as the user? Or does his IP also have to be the same as ...
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2answers
524 views

Is this an example of XSS attack?

A scripter sees on certain web pages it's technically possible to include markup like HTML and CSS/JS. It's technically possible to submit a javascript or iframe and have it display to the visitor ...
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4answers
642 views

Is XSS dangerous in application without database?

I think it definitelly isn't, because XSS which isn't saved anywhere would damage ONLY attacker. Am I right or are there any cases where XSS could hurt non-db-application? (I mean datas are not saved ...
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5answers
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Solution to allow JavaScript input but prevent XSS

We have a simple Blog system that allows users to input html and JavaScript to build a blog page. I'm aware that allowing javascript open up the door to xss attacks. We do however need to allow users ...
9
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2answers
718 views

Cross site scripting verification on a field which does not accept more than 20 characters

While performing penetration testing, I got stuck to a point. There is a text field which does not accept more than 20 characters(server side validation). I inserted following piece of code to check ...
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2answers
2k views

How to protect from new Javascript Injection technique that doesn't use eval()?

There is a new Javascript injection technique that is generating chatter on the forums mentioned here Here is the code sample: String.prototype.code = function(){ return (new Function('with(this) { ...
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2answers
584 views

Recent Facebook XSS exploit details

There was a recent XSS exploit on Facebook that posted a vulgar message and got users to click on a link to spread the payload. What vulnerability was exploited, and what can other sites do to avoid a ...
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4answers
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Does default ModSecurity protect enough against XSS?

It's been a few years since I mucked around with modsecurity... Will simply installing the package with the default rules provide enough validation to prevent any (okay, let's be honest - best we ...
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4answers
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Web Security Cheatsheet / ToDo list

Can anyone suggest a cheatsheet or ToDo list of web site and application security? A local small business owner prompted a question about web security, basically her company website just got XSS ...
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3answers
373 views

Is Content Security Policy an approach that is worth to support?

Mozilla Firefox 4.0 supports something called Content Security Policy that disables the interpretation of embedded Java Script. Only external Java Script files that are referenced using a script tag ...
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2answers
425 views

AntiXSS for ASP.NET 1.1

Unfortunately, a client of mine still has an application based on ASP.NET 1.1. Yes yes, I know - horribly insecure, support ending, and on and on... I've already been through that with them. ...
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4answers
141 views

Safely changing text links to HTML anchors

I'm trying to change text links to real anchors. So for example I want to change http://example.com to <a href="http://example.com">http://example.com</a>. Since this is a user given ...
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3answers
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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
332 views

Is this enough to tackle script / malicious code insertion in GET, POST requests?

I've got legacy PHP code which attempts to prevent script / SQL injection with the following: if (!empty($_POST)) { reset($_POST); while (list($k,$v)=each($_POST)) { ...
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votes
3answers
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Altering a $_SESSION variable in PHP via XSS?

Not sure if what I'm saying makes sense... but is it possible for me to alter a $_SESSION variable from outside the target PHP script? One of our scripts uses a $_SESSION variable and I'm not sure if ...
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1answer
187 views

Replicating javascript actions from different website (XSS?)

I've got html / javascript code on my site like this: <a ...
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2answers
323 views

Protecting websites from outdated browsers and plugins via a whitelist/blacklist combination?

Aside from using browser headers, I want to blacklist/whitelist browser and plugins from my site so that I can prevent these older unpatched systems from (1) being a general user of my site (2) ...
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2answers
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How to address XSS security issues in FCKeditor / CKeditor?

A security report we conducted through an outside company reported XSS vulnerabilities in FCKeditor which we're using in our PHP application. They pointed out that accessing URLs such as: ...
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6answers
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Can anybody explain XSS? [closed]

I work programming Enterprise Java applications and do very little web development in 2002. I'm interested in security and like to read articles about it. However, I never fully understand how XSS ...
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4answers
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Escaping JavaScript constants

how can untrusted values be included in a html-page as javascript string constants? Although the case i am asking uses JSF and Rails, I think this is a general problem independent of the server side ...
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7answers
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Whitelisting DOM elements to defeat XSS

As we know, developers are responsible for correctly escaping/validating data provided by the user before rendering or storing them. However, we must agree that it's relatively easy to forget a single ...
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5answers
4k views

New XSS cheatsheet?

There is a great list of XSS vectors avaliable here: http://ha.ckers.org/xss.html, but It hasn't changed much lately (eg. latest FF version mentioned is 2.0). Is there any other list as good as this, ...
25
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6answers
368 views

User input data, is filtering enough or should it be parsed?

In a webapplication there could be two approaches to migate XSS attacks. All the input data could be filtered (removing all 'bad' data), or the input could be parsed, tokenized and output with only ...
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3answers
1k views

Rails - protection against code injection and XSS

I've started using Ruby on Rails, and I was wondering if there were any security gotchas to watch out for with Rails, particularly regarding code injection and XSS? I know Rails tries to prevent ...