If source code is altered then redirect - javascript

Is it possible to use jQuery/Javascript to see if a webpages source code is altered by a visitor and if so redirect them?
And by altered, I mean if they open firebug or something and edit anything on the page once its finished loading?

This seems like a hack to prevent people from messing with your forms.
This is most definitely not the right way to make your site more secure; security must always come from the server-side or, if everything is done via the front-end, in a way that can only hurt the user who is currently signed in.
Even if you did succeed in implementing this using JavaScript, the first thing I would do is disable exactly that :) or just disable JavaScript, use wget, inspect the code first, then write a curl work-around, etc.

Even if there is a way to do that, the visitor can still edit this verification, so this is pointless.

yes. at the loading store the innerhtml of the html element in a string.
then set an interval every second to check if the current html matches the stored var.

Related

How can i prevent theft of javscript code [duplicate]

I know it's impossible to hide source code but, for example, if I have to link a JavaScript file from my CDN to a web page and I don't want the people to know the location and/or content of this script, is this possible?
For example, to link a script from a website, we use:
<script type="text/javascript" src="http://somedomain.example/scriptxyz.js">
</script>
Now, is possible to hide from the user where the script comes from, or hide the script content and still use it on a web page?
For example, by saving it in my private CDN that needs password to access files, would that work? If not, what would work to get what I want?
Good question with a simple answer: you can't!
JavaScript is a client-side programming language, therefore it works on the client's machine, so you can't actually hide anything from the client.
Obfuscating your code is a good solution, but it's not enough, because, although it is hard, someone could decipher your code and "steal" your script.
There are a few ways of making your code hard to be stolen, but as I said nothing is bullet-proof.
Off the top of my head, one idea is to restrict access to your external js files from outside the page you embed your code in. In that case, if you have
<script type="text/javascript" src="myJs.js"></script>
and someone tries to access the myJs.js file in browser, he shouldn't be granted any access to the script source.
For example, if your page is written in PHP, you can include the script via the include function and let the script decide if it's safe" to return it's source.
In this example, you'll need the external "js" (written in PHP) file myJs.php:
<?php
$URL = $_SERVER['SERVER_NAME'].$_SERVER['REQUEST_URI'];
if ($URL != "my-domain.example/my-page.php")
die("/\*sry, no acces rights\*/");
?>
// your obfuscated script goes here
that would be included in your main page my-page.php:
<script type="text/javascript">
<?php include "myJs.php"; ?>;
</script>
This way, only the browser could see the js file contents.
Another interesting idea is that at the end of your script, you delete the contents of your dom script element, so that after the browser evaluates your code, the code disappears:
<script id="erasable" type="text/javascript">
//your code goes here
document.getElementById('erasable').innerHTML = "";
</script>
These are all just simple hacks that cannot, and I can't stress this enough: cannot, fully protect your js code, but they can sure piss off someone who is trying to "steal" your code.
Update:
I recently came across a very interesting article written by Patrick Weid on how to hide your js code, and he reveals a different approach: you can encode your source code into an image! Sure, that's not bullet proof either, but it's another fence that you could build around your code.
The idea behind this approach is that most browsers can use the canvas element to do pixel manipulation on images. And since the canvas pixel is represented by 4 values (rgba), each pixel can have a value in the range of 0-255. That means that you can store a character (actual it's ascii code) in every pixel. The rest of the encoding/decoding is trivial.
The only thing you can do is obfuscate your code to make it more difficult to read. No matter what you do, if you want the javascript to execute in their browser they'll have to have the code.
Just off the top of my head, you could do something like this (if you can create server-side scripts, which it sounds like you can):
Instead of loading the script like normal, send an AJAX request to a PHP page (it could be anything; I just use it myself). Have the PHP locate the file (maybe on a non-public part of the server), open it with file_get_contents, and return (read: echo) the contents as a string.
When this string returns to the JavaScript, have it create a new script tag, populate its innerHTML with the code you just received, and attach the tag to the page. (You might have trouble with this; innerHTML may not be what you need, but you can experiment.)
If you do this a lot, you might even want to set up a PHP page that accepts a GET variable with the script's name, so that you can dynamically grab different scripts using the same PHP. (Maybe you could use POST instead, to make it just a little harder for other people to see what you're doing. I don't know.)
EDIT: I thought you were only trying to hide the location of the script. This obviously wouldn't help much if you're trying to hide the script itself.
Google Closure Compiler, YUI compressor, Minify, /Packer/... etc, are options for compressing/obfuscating your JS codes. But none of them can help you from hiding your code from the users.
Anyone with decent knowledge can easily decode/de-obfuscate your code using tools like JS Beautifier. You name it.
So the answer is, you can always make your code harder to read/decode, but for sure there is no way to hide.
Forget it, this is not doable.
No matter what you try it will not work. All a user needs to do to discover your code and it's location is to look in the net tab in firebug or use fiddler to see what requests are being made.
From my knowledge, this is not possible.
Your browser has to have access to JS files to be able to execute them. If the browser has access, then browser's user also has access.
If you password protect your JS files, then the browser won't be able to access them, defeating the purpose of having JS in the first place.
I think the only way is to put required data on the server and allow only logged-in user to access the data as required (you can also make some calculations server side). This wont protect your javascript code but make it unoperatable without the server side code
I agree with everyone else here: With JS on the client, the cat is out of the bag and there is nothing completely foolproof that can be done.
Having said that; in some cases I do this to put some hurdles in the way of those who want to take a look at the code. This is how the algorithm works (roughly)
The server creates 3 hashed and salted values. One for the current timestamp, and the other two for each of the next 2 seconds. These values are sent over to the client via Ajax to the client as a comma delimited string; from my PHP module. In some cases, I think you can hard-bake these values into a script section of HTML when the page is formed, and delete that script tag once the use of the hashes is over The server is CORS protected and does all the usual SERVER_NAME etc check (which is not much of a protection but at least provides some modicum of resistance to script kiddies).
Also it would be nice, if the the server checks if there was indeed an authenticated user's client doing this
The client then sends the same 3 hashed values back to the server thru an ajax call to fetch the actual JS that I need. The server checks the hashes against the current time stamp there... The three values ensure that the data is being sent within the 3 second window to account for latency between the browser and the server
The server needs to be convinced that one of the hashes is
matched correctly; and if so it would send over the crucial JS back
to the client. This is a simple, crude "One time use Password"
without the need for any database at the back end.
This means, that any hacker has only the 3 second window period since the generation of the first set of hashes to get to the actual JS code.
The entire client code can be inside an IIFE function so some of the variables inside the client are even more harder to read from the Inspector console
This is not any deep solution: A determined hacker can register, get an account and then ask the server to generate the first three hashes; by doing tricks to go around Ajax and CORS; and then make the client perform the second call to get to the actual code -- but it is a reasonable amount of work.
Moreover, if the Salt used by the server is based on the login credentials; the server may be able to detect who is that user who tried to retreive the sensitive JS (The server needs to do some more additional work regarding the behaviour of the user AFTER the sensitive JS was retreived, and block the person if the person, say for example, did not do some other activity which was expected)
An old, crude version of this was done for a hackathon here: http://planwithin.com/demo/tadr.html That wil not work in case the server detects too much latency, and it goes beyond the 3 second window period
As I said in the comment I left on gion_13 answer before (please read), you really can't. Not with javascript.
If you don't want the code to be available client-side (= stealable without great efforts),
my suggestion would be to make use of PHP (ASP,Python,Perl,Ruby,JSP + Java-Servlets) that is processed server-side and only the results of the computation/code execution are served to the user. Or, if you prefer, even Flash or a Java-Applet that let client-side computation/code execution but are compiled and thus harder to reverse-engine (not impossible thus).
Just my 2 cents.
You can also set up a mime type for application/JavaScript to run as PHP, .NET, Java, or whatever language you're using. I've done this for dynamic CSS files in the past.
I know that this is the wrong time to be answering this question but i just thought of something
i know it might be stressful but atleast it might still work
Now the trick is to create a lot of server side encoding scripts, they have to be decodable(for example a script that replaces all vowels with numbers and add the letter 'a' to every consonant so that the word 'bat' becomes ba1ta) then create a script that will randomize between the encoding scripts and create a cookie with the name of the encoding script being used (quick tip: try not to use the actual name of the encoding script for the cookie for example if our cookie is name 'encoding_script_being_used' and the randomizing script chooses an encoding script named MD10 try not to use MD10 as the value of the cookie but 'encoding_script4567656' just to prevent guessing) then after the cookie has been created another script will check for the cookie named 'encoding_script_being_used' and get the value, then it will determine what encoding script is being used.
Now the reason for randomizing between the encoding scripts was that the server side language will randomize which script to use to decode your javascript.js and then create a session or cookie to know which encoding scripts was used
then the server side language will also encode your javascript .js and put it as a cookie
so now let me summarize with an example
PHP randomizes between a list of encoding scripts and encrypts javascript.js then it create a cookie telling the client side language which encoding script was used then client side language decodes the javascript.js cookie(which is obviously encoded)
so people can't steal your code
but i would not advise this because
it is a long process
It is too stressful
use nwjs i think helpful it can compile to bin then you can use it to make win,mac and linux application
This method partially works if you do not want to expose the most sensible part of your algorithm.
Create WebAssembly modules (.wasm), import them, and expose only your JS, etc... workflow. In this way the algorithm is protected since it is extremely difficult to revert assembly code into a more human readable format.
After having produced the wasm module and imported correclty, you can use your code as you normallt do:
<body id="wasm-example">
<script type="module">
import init from "./pkg/glue_code.js";
init().then(() => {
console.log("WASM Loaded");
});
</script>
</body>

Can a javascript closure function be altered by a user?

we have a code that makes some stuff:
$(function(){
//websocket connection
//ajax requests
//other stuff
});
if the code was loaded the browser has compiled it, so can the user change this code and reload the page with the altered code?
because function that are inside this anonymous jquery function can't be executed in the browser console, thus they are not accessable, the question is: are there any posibilities to hack this type of code?
A user could just copy the anonymous function, including the code inside, to his console, and run it.
Basically, any and all code you send to the client can be accessed, modified, and run.
Validate anything that needs to be validated, server-side. Use client-side validation only to make your application "prettier".
It can be easily copy to console in Google Chrome for example, changed and fired from there. And user can easily see this script for example in Sources tab. So yes, it's possible.
So if it's function that user cannot see I reccomend not to use Javascript or any script language on the client side.
I don't know what is your issue in particular, but a couple of recommendations.
Never trust the user, nor anything that comes from the client. It can be easily manipulated. ALWAYS check the data server side. Check that the fields are the correct type, especially in languages like PHP, never use the entire POST data, always filter it.
Minify your code and use closure this way you reduce the change the user can mess with your code
Give access to user only to the parts that are his responsibility, this way if he messes with your code only he is damaged.
Use secure cookies and https if you can. Check CSRF and XSS, and use ways to be safe of this.
You can't avoid that the user will do as he pleases, but you can make so he can only touch his data

Secure URL/application

I was reading this article
http://msdn.microsoft.com/en-us/magazine/hh708755.aspx
related to securing Asp.net Application, but one thing i am not able to understand like i am browing url http://www.abc.com/XSS.aspx?test=ok and if i replace it with http://www.abc.com/XSS.aspx?test=alert('hacked')... how the site is not safe or hacked?The point i am trying to make here is that it is not impacting or affecting the site?
The example i have mentioned above, is mentioned at many places whereever it discusses security,but didn't understand
Just imagine this if you are going to output the value of "test"(without escaping it properly for html usage) on your html page then one could possibly inject any javascript on your page !! Some possible exploits could be changing the background to something obscene or even redirecting your page to some scam websites .. in effect making you accessory to fraud of somekind !!
ALWAYS USE PROPER ESCAPING FOR STORING OR USING USER SUBMITTED INFORMATION!!
Edit: The escaping I am talking about will be useful so that people dont inject html or JS in your database. This would eventually lead to every user getting the injected HTML/JS (if the injected variable is same for everyone) on their page .. not just the user who injected it !!

How to secure javascript code from being run on other domain (stolen) ? need more ideas

First, this could look like duplicate for
How to prevent your JavaScript code from being stolen, copied, and viewed ?
And other, but it's not.
I search for ideas that can do, that stealing of JS can be very hard
Some of my examples:
of course obfuscate code
use a document.location an check if some
letter in domain equals to letter on that position where script
normally works
use part of this location in function call, something like eval('first_part_of_function_name'+part_from_location+'third_pard(parameters)');
store some important constant need in application in some element in your page-design, and get it from there in JS like $('#header div.onright a rel')
get some portion of script by AJAX and eval() it
add to script some unnecessary function, instructions.
check for existance of some elements in page (copyright text on footer)
generate some time-variable hash in PHP and put in JS, where will be function that checks this hash and current time to work or not
maybe use of other JS files ? or events binded to elements hidden in very common scripts (like bind some action in jquery-min.X.X.X.js file where all jquery is.
Are they good ideas ? Have some more ? I think that most important can be variety of things wich you can do with document location, is that the only element that will be driffrent than working in normal coditions on our site ?
No matter how complex you make your code, it can always be read, if necessary with abstract interpretation, i.e. automatically capturing the essence of your code. Code without knowledge of internals, variable names (I assume you're already using minimization, for example with the YUI compressor), documentation, support, and generalization is worthless for anyone else.
If a competitor (or potential customers) of yours is stealing your code, consider simply suing them. If it's some random guy on the internet, why do you care?
One more tool http://closure-compiler.appspot.com/home

Is there a way to validate the HTML of a page after AJAX operations are performed on it?

I'm writing a web app that inserts and modifies HTML elements via AJAX using JQuery. It works very nicely, but I want to be sure everything is ok under the bonnet. When I inspect the source of the page in IE or Chrome it shows me the original document markup, not what has changed since my AJAX calls.
I love using the WC3 validator to check my markup as it occasionally reminds me that I've forgotten to close a tag etc. How can I use this to check the markup of my page after the original source served from the server has been changed via Javascript?
Thank you.
Use developer tool in chrome to explore the DOM : it will show you all the HTML you've added in javascript.
You can now copy it and paste it in any validator you want.
Or instead of inserting code in JQuery, give it to the console, the browser will then not be able to close tags for you.
console.log(myHTML)
Both previous answers make good points about the fact the browser will 'fix' some of the html you insert into the DOM.
Back to your question, you could add the following to a bookmark in your browser. It will write out the contents of the DOM to a new window, copy and paste it into a validator.
javascript:window.open("").document.open("text/plain", "").write(document.documentElement.outerHTML);
If you're just concerned about well-formedness (missing closing tags and such), you probably just want to check the structure of the chunks AJAX is inserting. (Once it's part of the DOM, it's going to be well-formed... just not necessarily the structure you intended.) The simplest way to do that would probably be to attempt to parse it using an XML library. (one with an HTML mode that can be made strict, if you're not using XHTML)
Actual validation (Testing the "You can't put tag X inside tag Y" rules which browsers generally don't care too much about) is a lot trickier and, depending on how much effort you're willing to put into it, may not be worth the trouble. (Because, if you validate them in isolation, you'll get a lot of "This is just a fragment" false positives)
Whichever you decide to use, you need to grab the AJAX responses before the browser parses them if you want a reliable test result. (While they're still just a string of text rather than a DOM tree)

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