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Hacking Front-End Apps
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Alex Sexton
February 12, 2014
Technology
4
2.3k
Hacking Front-End Apps
My talk on client side web security as given at the jQuery Conference 2014 in San Diego
Alex Sexton
February 12, 2014
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Transcript
Hacking Front-End Apps Alex Sexton
I work at .
which is in . California
but…
I live in . Texas
The web has a lot in common with Texas.
“The wild west.”
In 1985, Texas had a problem.
None
Littering
Some Texans defended their “God-given right to litter.”
ಠ_ಠ
There were fines for littering.
photo by Curtis Gregory Perry
But no one seemed to care.
The state tried some slogans.
None
But these slogans apparently did not resonate with the core
offenders
Males 18-24 “Bubbas in Pickup Trucks”
In 1985 Texas tried a new campaign:
None
The campaign reduced litter on Texas highways ! 72% !
from 1986 to 1990.
My point is…
“Hey everyone, you should make your websites more secure because
it’s important.” ! Probably isn’t going to do the trick.
DON’T! MESS! WITH! XSS Also probably won’t work.
Web developers, not security researchers, are the core audience.
Web security is hard.
“All you have to do is never make a single
mistake.” - I Think Mike West
“I discount the probability of perfection.” - Alex Russell
Content Injection
None
None
None
Everyone has a friend that always seems to pick “<script>alert(‘hacked!’);</script>”
as their username.
My User Agent
My Friend, Mike Taylor’s User Agent Mozilla/5.0 (Macintosh; Intel Mac
OS X 10.9; rv:25.0) <script>alert(‘lol’);</script> Gecko/20100101 Firefox/25.0
My Friend, Mike Taylor’s User Agent Mozilla/5.0 (Macintosh; Intel Mac
OS X 10.9; rv:25.0) <script>alert(‘lol’);</script> Gecko/20100101 Firefox/25.0
ಠ_ಠ
Samy
None
None
None
ಠ_ಠ
So let’s just detect malicious scripts!
None
alert(1)
The Billy Hoffman Whitespace Attack <script> ! </script>
The Billy Hoffman Whitespace Attack <script> ! </script> Malicious
Code
The Billy Hoffman Whitespace Attack <script> ! </script> tab
tab tab space space
The Billy Hoffman Whitespace Attack <script> ! </script> 1
1 1 0 0
You cannot detect malicious code.
output.replace(/<script>/, ‘’);
CSS Hacks
Old School
None
Link Visited Link getComputedStyle( getComputedStyle( ) ) === \o\|o|/o/ Pretty
much People Celebrating (or screaming on fire)
Timing Attacks
Security by Inaccuracy
requestAnimationFrame + :visited = ಠ_ಠ
requestAnimationFrame + :visited = ಠ_ಠ
requestAnimationFrame + :visited = ಠ_ಠ
Link Visited Link
Link Visited Link <16ms >60ms Time to render
JSON-P
MORE LIKE JSON-Pretty-Insecure
“I’d really like it if someone could run arbitrary dynamic
scripts on my page” - JSONP Users
You wouldn’t do this.
So don’t do this.
A Leak In The Response
YouProbablyShouldUseCORS.tumblr.com
enable-cors.org
Try to say CROSS SITE! REQUEST FORGERY 5 times fast.
Set-Cookie ‘csrf=0003’
Set-Cookie ‘csrf=0003’
None
None
None
It gets worse.
Contextis White Paper
Cross-Domain Data Snooping via SVG Filters and OCR
None
ಠ_ಠ
We need a new approach.
Content Security Policy
None
Disallow Inline JS, CSS By Default!
Disallow eval By Default!
Disallow Cross Domain JS, CSS, IMG, Fonts
Report Violations!
None
A White List That’s the key!
Good Security Goes Beyond Content Injection
<iframe sandbox>
HTTPS Everywhere
HTTPS Everywhere
HTTPS Only
301 Redirect http
https HSTS
Frame Busting
Disallow as an iFrame X-Frame-Options
It’s “security by default.” At least much closer…
You can rely a little less on being perfect.
it only matters if everyone buys in. But
We need our own slogan.
We need developers to take pride in making secure applications.
Don’t Mess With The Web
ಠ_ಠ
Let’s do something about it together.
Thanks! @SlexAxton Special Thanks To: Mike West * 1000 Adam
Baldwin Contextis MDN