HTML (HyperText Markup Language) is a language used to created web pages.

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55
votes
1answer
3k views

“Allow __ to be fullscreen?”

I have been asking myself for a while what's the purpose of that popup showing up in pretty much all the modern browsers upon entering the full-screen mode of a video or website. It appears to be a ...
43
votes
4answers
11k views

Should websites be allowed to disable autocomplete on forms or fields?

Currently, there is an HTML form/input attribute called autocomplete, which, when set to off, disables autocomplete/autofill for that form or element. Some banks seem to use this to prevent password ...
12
votes
3answers
660 views

What does a HTML filter need to do, to protect against SVG attacks?

I recently learned that SVG (Scalable Vector Graphics) images introduce a number of opportunities for subtle attacks on the web. (See paper below.) While SVG images may look like an image, the file ...
10
votes
1answer
266 views

Should Content in <noscript> Blocks Be Escaped

The title pretty much says it all. It seems counter-intuitive to escape inside a <noscript> block because any js that an attacker is able to inject there shouldn't be executed. But, I'm still ...
10
votes
1answer
728 views

How can I embed iframe securely without restricting its functionality?

I'd want to embed an iframe from untrusted site into web application. Iframe: should be able to run Javascript and browser plugins (Flash, etc.) should not be able to access my web application ...
8
votes
3answers
1k views

Allowing users to input a safe subset of HTML

I recently posted this question on Code Review and it was recommended that I ask you guys about it. Basically, this will be used to allow users to generate formatted content. It gets put inside of ...
8
votes
3answers
3k views

Is there a way to bypass Django's XSS escaping with “unicode”?

Django (the Python web framework) escapes output to prevent XSS (Cross Site Scripting) attacks. It replaces ', ", <, >, & with their HTML safe versions. However this presentation on slide ...
8
votes
2answers
834 views

Attack Vectors for Purely Static Website (HTML and CSS)

I am sorry if this is a too trivial question, but once I was told that only a fool is sure of anything: as I am not sure about this question, I am willing to risk my neck by asking it anyway, all in ...
7
votes
6answers
669 views

Cleartext password in HTML

Is there any problem with outputing a user's password to the HTML in an hidden field (see use case below before flaming xD)? The use case is a registration form with two steps. The user fills in the ...
7
votes
1answer
2k views

What possible use does an iFrame have for security?

I'm looking at code for an old login form I'm redesigning. It's a simple table with two input fields for username and password. But just before the end </table> tag there's a blank iFrame which ...
7
votes
4answers
262 views

Limited JavaScript app scenario: Attack vectors and mitigation

I'm going to be developing a single page JavaScript app which allows input via a textarea. This input is never sent to the server, never shown to another user, and will only be persisted in browser ...
7
votes
2answers
877 views

Drupal filters XSS with regexes. What could bypass it?

Drupal filters HTML strings against XSS attacks using regexes: http://api.drupal.org/api/drupal/includes%21common.inc/function/filter_xss/7 However, as a lot of people know, HTML can't be parsed with ...
5
votes
2answers
758 views

Should every output element be filtered, or just those which contain user-editable data? [duplicate]

I'm combing through a legacy app updating SQL to prevent Injections and XSS vulnerabilities. I know to apply PHP's htmlspecialchars() anything that is directly passed to a script and displayed on a ...
5
votes
3answers
461 views

Escaping rich text editor output

When having a rich text editor on a web application, what is the best way to escape HTML entities and prevent XSS attacks but keep the formatting (<b>, <i>, <u>, ...etc.) ?
5
votes
1answer
2k views

What are the benefits and drawbacks of the HTML5 Keygen element?

As of January 2013, what are the potential benefits and drawbacks of the HTML5 Keygen element?
5
votes
2answers
607 views

Workarounds for :visited CSS History reconnaissance

Several years ago it was possible to use a:visited { background: url('/log.php'); } to figure out on what website user has been previously. But now it is restricted by browsers. Is there any ...
5
votes
2answers
467 views

Closing an HTML tag without using the actual character

I'm currently learning how to perform XSS on websites, but there is a constant problem that keeps recurring that I'm sure must be easy to bypass. Quite often, the website will filter out quotation ...
5
votes
2answers
158 views

Any eventhandlers that apply to hidden elements?

Im trying to XSS a search field and my attack vector is getting reflected like this: <input type="text" id="txtRpHiddenKeyword" style="display: none;" value="ATTACK VECTOR HERE" /> Only ...
4
votes
4answers
716 views

Is it possible to make an xss with only html tags

I'm not aware of all the xss tricks.. While programming in Ruby on Rails, using a sanitize method to allow only certain tags and it makes its best to clear all the other tags and scripts the ...
4
votes
4answers
1k views

Is this an attack and how can I fix it?

I don't know where to start in searching the forum for existing threads that might cover my issues. I recently received a spoof email pretending to be from a client for whom I've just started to do ...
4
votes
3answers
3k views

Is it possible for a hacker to bypass upload php file?

I wanna give a filtering system in my script. here it is : <?php $allowedExts = array("gif", "jpeg", "jpg", "png","bmp"); $temp = explode(".", $_FILES["file"]["name"]); $extension = end($temp); ...
4
votes
2answers
123 views

To What Extent does an Attacker Have Access to the Browser History through the CSS Pseudoclass :visited Styles?

I have read this article on how a scripted web page is able to obtain the visited history of a user browsing the page. However, I can't find any clear information in the article describing the extent ...
4
votes
3answers
1k views

Sharing Nmap scan results in a web page

Is there a tool that allow the sharing of nmap scan results ? I know nmap can produce XML and I can easily convert them in HTML. I would like to know if there is a tool with more features. For ...
4
votes
1answer
720 views

OWASP Recommendation on Client-Side Password Hashing

The OWASP Application Security FAQ recommends the use of JavaScript to produce a salted hash of the password client-side with JavaScript prior to sending it to the server. Is this something truly ...
3
votes
4answers
3k views

how can you inject malicious code into an innocent-looking URL?

I am learning about XSS attacks. Wikipedia says that in a non-persistent attack an attacker may provide an innocent-looking URL that "points to a trusted site but actually has an XSS vector." What ...
3
votes
3answers
584 views

Stop code injections into page code

I started a topic HERE on the stackoverflow site, but was refered here. I did get some info there, but think it need's more indepth input. So hopefuly people here can help. I have a few domains ...
3
votes
2answers
321 views

Injecting information in a web page (Gmail). Does it raise security problem?

I am developing a Google Chrome extension which encrypts/decrypts emails for Gmail users. So, I detect encrypted emails when the user opens an email on using tags. Once an encrypted email has been ...
3
votes
1answer
183 views

Danger of hidden html form uploading users local files without their knowledge

Is there a danger that a webpage could have a hidden form with a file upload input and js script that would try and take a random guesses at files on a users system and attach them to the form and ...
3
votes
1answer
404 views

How can I check the iframe on my website is secure or not?

My website has an iframe used for loading my client's websites (only 5).How can I make sure the iframe is secure? Also by editing iframe src It allows to load any other websites.How can I prevent it?
2
votes
4answers
363 views

Clickjacking: can't browsers just forbid/reject placing transparent elements over frames?

Why not? Seems like this is only used for clickjacking, the solution should be simple enough.
2
votes
5answers
184 views

Is converting `<` to `&lt;` sufficient to prevent execution of JavaScript from arbitrary HTML?

This is kind of a bar-bet question. An acquaintance of mine has made the claim that, given an arbitrary glob of HTML, it can be completely prevented from executing JavaScript if, before slapping it ...
2
votes
4answers
952 views

Simple solution to XSS

I've got an idea as to how to defeat XSS so simple that it may work and was wondering if anybody had already done something similar. The goal here is not efficiency but security. In other words I ...
2
votes
5answers
1k views

Is it secure to use jQuery on the server-side for user input validation?

I'm thinking about using jQuery on the server-side (node.js) to validate user input (filter tags, remove every attributes except href, rel, target & style, modify css rules which are applied ...
2
votes
3answers
2k views

Javascript containing a long hexadecimal string and eval: is this suspicious?

At the bottom of the index.php file for a simple “contact us” form, I found the following (some whitespace and newlines added): try {if(window.document)--document.getElementById('12')} catch(qq) ...
2
votes
4answers
435 views

HTML Entities to hide Email Addresses

I'm on WordPress trying to keep spambots from grabbing email addresses that may be in The Content. WordPress has a nifty little function simply called antispambot() which will convert the email ...
2
votes
2answers
90 views

is it sufficient to convert '(single-quote) to ` &#039; `

Is it sufficient to convert ' to &#039; , > converted to &gt; and < converted to &lt; to avoid xss A bit of context: the payload would be going through the URL and landing in a ...
2
votes
3answers
252 views

OWASP escaping recommendation - why /?

In OWASP recommendations regarding escaping untrusted input for HTML element content, they list the following: & --> &amp; < --> &lt; > --> &gt; " --> &quot; ' ...
2
votes
3answers
428 views

How can I bypass double quotes in a attribute based xss attack

The code that I have is: <input type="text" name="some_name" value="<?php echo CHtml::encode($str); ?>" /> $str is the input data. 'CHtml::encode()' is Yii's way of encoding special ...
2
votes
1answer
104 views

Chrome inline JavaScript string interpreatation

If you have an HTML file that contains the following code : <!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> </head> ...
2
votes
3answers
819 views

Why are scripts injected through innerHTML not executed whilst onerror and other on<event> attributes on elements are? - Google XSS Challenge 2

SPOILER ALERT : Do not continue if you do not want to be spoiled I am currently doing the Google XSS Challenge Level 2 . I am injecting XSS code that is inserted into the document using ...
2
votes
2answers
445 views

Hacked HTML page - what's in the comment following the obfuscated code?

Chrome just warned me about malicious content when visiting a site - so I visited it. The source code is like the following: <html> <head> <link href="images/DPT2.ico" title="Dynamic ...
2
votes
1answer
146 views

Sandboxing user input html

I want to render user uploaded HTML (consisting of possibly many files with images, custom css, custom js, all uploaded in a zip file) for preview purpose. The user that submits the html will be the ...
2
votes
2answers
441 views

HTTPOnly Cookies: Security Depends on Client Cooperation?

I've been implementing HTTPOnly cookie-based session handling and have some questions about what HTTPOnly means. I realise it's a flag that gets passed around in the HTTP header when setting cookies. ...
2
votes
1answer
152 views

Is preventing XSS/HTML Injection really this simple?

A colleague suggested to me just to prevent letter characters from occurring immediately after an opening angle bracket as a way to protect against XSS and HTML injection. Obviously, this doesn't ...
2
votes
1answer
88 views

XSS: alert() not executed on different OS/computer

I've encountered a strange behavior while I was performing a security audit of a web application. Some user controlled inputs were displaying their values, unencoded, into the page that processed the ...
2
votes
1answer
89 views

encodeURIComponent in a unquoted HTML attribute

My gut feeling is that the following should be attackable: $("<td><a href=somefile.php?url="+encodeURIComponent(somevar)+">Download Here</a></td>"); In contrast to ...
2
votes
2answers
580 views

Content-Security-Policy hash of script

<?php header("Content-Security-Policy: default-src 'sha256-".base64_encode(hash('sha256', 'console.log("Hello world");', true))."'"); ?> <script>console.log("Hello world");</script> ...
1
vote
1answer
76 views

Couldn't websites that want to track our activity just store the data in the DOM?

For example as the value of an attribute of a html tag. <div cookie='id=1234'></div> Then if the user deletes the cookies while at least one page of the website is open, a javascript ...
1
vote
3answers
80 views

Make all form inputs safe but allow any type of input including code

Pastebin allow you to (along with plenty of other sites) input code into there forms. I know that this can be a huge security threat if not done properly so I would like to know how they go about ...
1
vote
1answer
910 views

“pagesinxt.com” links in the sourcecode, am I being hacked?

At this moment I am being hacked and I do not know to stop it. Let me explain... My website is hosted in a VPS where I am the only person who has access to it. The page is builtwith ...