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Weaponizing Unicode: Homographs Beyond IDNs

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Who Am I

The Tarquin (aka Aaron M Brown)Senior Security Engineer

Amazon.com

@TheTarquin

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Disclaimers

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WTF, Why?

“The human race will begin solving its problems on the day that it ceases taking itself so seriously.” - Malaclypse the Younger

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Scope, Context, and Prior Art

http://www.xn--exmple-qxe.com/

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The Dark Corners of Unicode

ꓮvs vs ᴀ vs � �

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Scope of the Problem

Α

Uppercase Greek Alpha u+0391

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Scope of the Problem

ı̇

Latin Small Letter Dotless I (u+0131) + Combining Dot Above (u+0307)

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Scope of the Problem

�

Mathematical MonoSpace Capital Z u+1D689

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Scope of the Problem

₨

Rupee Sign, u+20A8

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Not to be Confused With

₹

Indian Rupee Sign, u+20B9

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Oh come on, Unicode

ᚁ

Ogham letter Beith u+1681

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Let’s Hack Shit

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Search and Indexing

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Do you want to play a game‽

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Defeating Plagiarism Detection

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Defeating Plagiarism Detection

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Lol text analysis

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Lol text analysis

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Lol spellcheck

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Lesson 1: Unicode support usually just means “passed my unit tests”.

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Defeating ML Systems

“Explanations exist; they have existed for all time; there is always a well-

known solution to every human problem [which is] neat, plausible, and

wrong.” - H. L. Mencken

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Default Data Set

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Homographs, in MY Training Set?

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100% Homographs in Neg Training

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10% Homographs in Neg Training

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Sabotaging a Cinematic Masterwork

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Sabotaging a Cinematic Masterwork

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Sabotaging a Cinematic Masterwork

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Lesson 2: ML overindexes on human-invisible patterns. If a human

could see them, we wouldn’t be using ML.

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But emojis aren’t the real problem

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Demo

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Lesson 3: Homographs work because people don’t see the the text; they see whatever it

represents.

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Canary Traps, And Repudiation

Canary Traps: when you want to know who’s “singing”

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Canary Traps, And Repudiation

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Homographs, Canary Traps, And Repudiation

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Homograph Bombs

Go ́ód ñ̃evvs, h cke ₨�⇥ ⇤

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And now, for the world’s most boring demo...

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Tool Intro: samesame

Because small, sharp tools are the best.

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Tool Intro: samesame

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Defense

“Every man takes the limits of his own field of vision for the limits of the world.” - Arthur Schopenhauer

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Demo Time!

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OCR Defense

Why do this instead of $alternative?

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Lesson 4: Defenses work best when they directly exploit attacker

incentives

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Conclusions!

Phenomenology is king.

Hacking computer is fun; hacking people is more effective

Unicode is a delightfully absurd monstrosity and I love it.

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GreetzAmazon colleagues especially David Gabler and Nikki Parekh

The Additional Payphones Crew: cibyr, cobells, giskard, dirac, and turbo

All the DefCon organizers, goons, and other crew

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�ƀ� ө ᶌ &Αɨ��� ⲅ � ��Ꭵԁ�