UI Redressing

self.Intro()

Works for Payatu Technologies (www.payatu.com) as an
AppSec Consultant.
Author of 'game|over' – A Linux distro built for learning web app
security.
Member of null – The Open Security Community www.null.co.in
Moderating the #null #Pune Chapter ;)
Very #Annoying too … so u might wanna shoot me in the head

<NOT_Certified>
C|EH , AFCEH .. or any other certification
</NOT_Certified>

Agenda

Introduction to UI Redressing/Clickjacking.
Elements of basic clickjacking.
Advanced Clickjacking techniques.
Some cool demos :)
Prevention techniques that Suck !!
Prevention techniques that dont ….

Running away as fast as I can before somebody shoots me in the
head.

So what is UI Redressing/Clickjacking ??

“ … is a malicious technique of tricking a Web user into
clicking on something different from what the user
perceives they are clicking on, thus potentially revealing
confidential information or taking control of their computer
while clicking on seemingly innocuous web pages ”

UI Redress attack a.k.a Clickjacking

The term "clickjacking" was coined by Jeremiah
Grossman and Robert 'RSnake' Hansen in 2008.

It is seen as a type of 'Confused Deputy' attack
against the browser ….....

Now you are confused ….......
arent you ??

Lets watch a video …....

Aaiilaa ... its NOT what it looks
like !!!

Pic taken from : http://detower.com/id12.html

In a nut-shell

Pic from :http://www.protecht.ca/blog/clickjacking-niagara

So what do we need to redress the UI

Iframes : Used to embed one website inside another.
Syntax : <iframe src=”null.co.in” ></iframe>

Opacity : Used to change the transparency of html
elements.

Stacking Order : Using the 'z-index' property we can
stack the HTML elements on top of one another.

Basic Clickjacking

[ Demo ]: Basic Clickjacking.

So what about text fields ?

Q: Is it possible to make a user enter text ??

A: YES !!!

Q: But how ??

Muhahahahahahaha...!!!

Advanced Clickjacking Techniques

[ Demo ]: Advanced Clickjacking attack.

[Demo]: Content Extraction using Drag and drop

So we can hijack clicks as well as text …..

Thats practically everything a user does ….

So how do we prevent UI Redress Attacks ??

Prevention techniques that don't always
work

*Yes I am still talking about Clickjacking

Frame Busters

“Frame buster / Framekiller is a piece of JavaScript code
that prevents a Web page from being displayed within a
frame.”

Basic Frame Busting code.

<script >
if
{
( top . l o c a t i o n != l o c a t i o n )
top . l o c a t i o n = s e l f . l o c a t i o n ;
}
</script>

Basic frame busters

[Demo:] Basic Frame Busters

Some common frame busters ..

Credits :
Busting Frame Busting:
a Study of Clickjacking Vulnerabilities
on Popular Sites.
By -Gustav Rydstedt, Elie Bursztein,
Dan Boneh Collin Jackson

Q: So are we safe from a UI Redress Attack ?
A: NO !!!

And here comes “Double Framing Attack”.

Busting Frame Busters

[Demo] : Double Framing Attack

[eg 1/1] Frame Busters gone wrong

Credits : Busting Frame Busting: A Study of Clickjacking Vulnerabilities on Popular Sites.
By -Gustav Rydstedt, Elie Bursztein, Dan Boneh Collin Jackson

So do Javascripts solve this issue ?

What if I hire
this guy to write a frame
buster for me

Am I safe ??

The best FrameBuster so far..

<script>

if (self == top)
{
document.documentElement.style.visibility='visible';
}
else
{
top.location = self.location;
}
</script>


Other ways of busting frame busters.

● IE7 var location = “clobbered”
<script> var location = "clobbered";
</script>
<iframe src="http://www.victim.com">
</iframe>
● [Demo] Google Chrome “sandbox”
● [Demo] window.onbeforeunload()

Prevention techniques that work

● Ask for a users password.

Prevention techniques that work

● CAPTCHA

Prevention techniques that will
always work

“ X-Frame-Options ”

*Just for the record we are still talking about Clickjacking

What are X-Frame-Options ?

“The X-Frame-Options HTTP response header
can be used to indicate whether or not a browser
should be allowed to render a page in a <frame>
or <iframe>.
Sites can use this to avoid clickjacking attacks, by
ensuring that their content is not embedded into
other sites.”
–- MDN

Using X-Frame-Options
There are three possible values for X-Frame-Options:

DENY
The page cannot be displayed in a frame, regardless of the
site attempting to do so.

SAMEORIGIN
The page can only be displayed in a frame on the same
origin as the page itself.

ALLOW-FROM uri
The page can only be displayed in a frame on the specified
origin.
--MDN

[Demo] : Setting X-Frame-Options in PHP

THANKS !!!!!

Remember …... Clickjacking is
LAME

LAMER
than

References

●[White Paper] Busting frame busting: a study of clickjacking vulnerabilities at
popular sites [BIBTEX] by Gustav Rydstedt, Elie Bursztein, Dan Boneh, and
Collin Jackson

● https://www.owasp.org/index.php/Clickjacking
● http://en.wikipedia.org/wiki/Clickjacking

● http://en.wikipedia.org/wiki/Framekiller

● http://andlabs.org/

● http://blog.skepticfx.com/2011/09/facebook-graph-api-access-token.html

UI Redressing

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