Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Hacking Front-End Apps
Search
Alex Sexton
February 12, 2014
Technology
3
2.4k
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
Tweet
Share
More Decks by Alex Sexton
See All by Alex Sexton
Your Very Own Component Library
slexaxton
5
740
Front-End Ops - jQuery Conf Chicago 2014
slexaxton
1
1k
Practicing Safe Script
slexaxton
18
2.8k
Other Decks in Technology
See All in Technology
さくらのIaaS基盤のモニタリングとOpenTelemetry/OSC Hokkaido 2025
fujiwara3
3
440
生まれ変わった AWS Security Hub (Preview) を紹介 #reInforce_osaka / reInforce New Security Hub
masahirokawahara
0
470
Enhancing SaaS Product Reliability and Release Velocity through Optimized Testing Approach
ropqa
1
230
United Airlines Customer Service– Call 1-833-341-3142 Now!
airhelp
0
170
SaaS型なのに自由度の高い本格CMSでサイト構築と運用のコスパ&タイパUP! MovableType.net の便利機能とユーザー事例のご紹介
masakah
0
110
生成AI活用の組織格差を解消する 〜ビジネス職のCursor導入が開発効率に与えた好循環〜 / Closing the Organizational Gap in AI Adoption
upamune
7
5.2k
freeeのアクセシビリティの現在地 / freee's Current Position on Accessibility
ymrl
2
190
KubeCon + CloudNativeCon Japan 2025 Recap by CA
ponkio_o
PRO
0
300
B2C&B2B&社内向けサービスを抱える開発組織におけるサービス価値を最大化するイニシアチブ管理
belongadmin
1
6.9k
Zero Data Loss Autonomous Recovery Service サービス概要
oracle4engineer
PRO
2
7.7k
高速なプロダクト開発を実現、創業期から掲げるエンタープライズアーキテクチャ
kawauso
2
9.2k
Connect 100+を支える技術
kanyamaguc
0
200
Featured
See All Featured
Documentation Writing (for coders)
carmenintech
72
4.9k
Done Done
chrislema
184
16k
Fashionably flexible responsive web design (full day workshop)
malarkey
407
66k
The Language of Interfaces
destraynor
158
25k
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
53
2.9k
The Illustrated Children's Guide to Kubernetes
chrisshort
48
50k
Distributed Sagas: A Protocol for Coordinating Microservices
caitiem20
331
22k
RailsConf 2023
tenderlove
30
1.1k
Optimising Largest Contentful Paint
csswizardry
37
3.3k
The Pragmatic Product Professional
lauravandoore
35
6.7k
Refactoring Trust on Your Teams (GOTO; Chicago 2020)
rmw
34
3.1k
GraphQLの誤解/rethinking-graphql
sonatard
71
11k
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