How Do Tor Users Interact With Onion Services? · Despite extra security and privacy properties of...
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How Do Tor Users Interact With Onion Services? Philipp Winter, Annie Edmundson, Laura Roberts, Agnieszka Dutkowska-Zuk, Marshini Chetty, Nick Feamster USENIX Security Symposium 15 August 2018 1
Transcript of How Do Tor Users Interact With Onion Services? · Despite extra security and privacy properties of...
How Do Tor Users Interact With Onion Services?
Philipp Winter, Annie Edmundson, Laura Roberts, Agnieszka Dutkowska-Zuk, Marshini Chetty, Nick Feamster
USENIX Security Symposium15 August 2018 1
Tor is a Decentralized Anonymity Network
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The Tor network
Onion Services Provide Server Anonymity
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The Tor network
How Do Users Interact with Onion Services?
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● What are users’ mental models of onion services?
● How do users use and manage onion services?
● What are the challenges of using onion services?
Main FindingsDespite extra security and privacy properties of onion services, many users are confronted with usability issues
● Discovering the existence of onion services● Managing and remembering onion domains● Susceptibility to phishing attacks
We can learn from the issues users have encountered to implement design improvements
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Overview
1. Onion Services Background + Features
2. Methods
3. Resultsa. Onion Sites Discovery
b. Vanity Domains
c. Verifying Onion Sites
4. Future Directions & Conclusions
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http://expyuzz4wqqyqhjn.onion
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http://expyuzz4wqqyqhjn.onion
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Special-use domain
http://expyuzz4wqqyqhjn.onion
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Truncated, base 32-encoded hash over RSA public key
http://expyuzz4wqqyqhjn.onion
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Not limited to HTTP(S)
Onion Service UI is Designed to be Seamless
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Onion Service UI is Designed to be Seamless
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Onion Service UI is Designed to be Seamless
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Onion Service UI is Designed to be Seamless
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Onion Services are Self-authenticating
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3wcwjjnuvjyazeza.onion
3wcwjjnuvjyazeza
The Tor network
Onion Services are Self-authenticating
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3wcwjjnuvjyazeza.onion
3wcwjjnuvjyazeza
The Tor network
Public key
Onion Services are Self-authenticating
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3wcwjjnuvjyazeza.onion
3wcwjjnuvjyazeza
The Tor network
Public key
SHA-1
Onion Services are End-to-end Encrypted
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3wcwjjnuvjyazeza
The Tor network
Onion Services are End-to-end Encrypted
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3wcwjjnuvjyazeza
The Tor network
Both Client and Server are Anonymous
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3wcwjjnuvjyazeza
The Tor network
Both Client and Server are Anonymous
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3wcwjjnuvjyazeza
The Tor network I talk to the client through relay R2
I talk to the onion service through relay R2
I have no idea who I’m talking to
While onion services provide anonymity benefits, they are not perfect.
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● Susceptible to traffic analysis attacks● Configuration errors● Usability issues
Overview
1. Onion Services Background + Features2. Methods3. Results
a. Onion Sites Discoveryb. Vanity Domainsc. Verifying Onion Sites
4. Future Directions & Conclusions
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How Do Users Interact with Onion Services?
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● What are users’ mental models of onion services?
● How do users use and manage onion services?
● What are the challenges of using onion services?
How Do Users Interact with Onion Services?
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Mixed-method user study
Interviews Survey DNS B Root Data
How Do Users Interact with Onion Services?
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Mixed-method user study
Interviews
● N=17
● Diverse backgrounds
● Exploratory
Survey DNS B Root Data
How Do Users Interact with Onion Services?
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Mixed-method user study
Interviews
● N=17
● Diverse backgrounds
● Exploratory
Survey
● N=517
● 49 questions (mix of open-ended and closed-ended)
● 4 attention checks
DNS B Root Data
How Do Users Interact with Onion Services?
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Mixed-method user study
Interviews
● N=17
● Diverse backgrounds
● Exploratory
Survey
● N=517
● 49 questions (mix of open-ended and closed-ended
● 4 attention checks
DNS B Root Data
● ~2 days of data
● Filtered correctly formatted .onion domains
● 15,471 leaked onion domains
Overview
1. Onion Services Background + Features2. Methods3. Results
a. Onion Sites Discoveryb. Vanity Domainsc. Verifying Onion Sites
4. Future Directions & Conclusions
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Makeshift Solutions Ease Onion Discovery
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Makeshift Solutions Ease Onion Discovery
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Makeshift Solutions Ease Onion Discovery
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Makeshift Solutions Ease Onion Discovery
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I wasn't aware that onion site search engines exist. It's been near impossible for me to find them so far.
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Survey Respondent (S195)
Onion Domain Management is Chaotic
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Onion Domain Management is Chaotic
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Onion Domains are Difficult to Remember
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Onion Domains are Difficult to Remember
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Meaningful prefixes appear to make remembering easier
Phonetic pronunciation plays a large part in how I remember onions.
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Survey Respondent (S46)
Vanity Onion Domains
propub3r6espa33w.onion
nytimes3xbfgragh.onion
facebookcorewwwi.onion
protonirockerxow.onion
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Vanity Onion Domains
propub3r6espa33w.onion
nytimes3xbfgragh.onion
facebookcorewwwi.onion
protonirockerxow.onion
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● Generate onion domains until hash resembles desired string
● The good:○ Hints at onion service
content
● The bad:○ Breeds false sense of
security○ Economically unfair
I only memorize the first part of the domain.
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Survey Respondent (S96)
I understand vanity onion domains are a sign of the weakness of the hash algorithm used by Tor.
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Survey Respondent (S454)
These people who created their onion name using scallion or other tools should notice that other people can make [the] same private key.
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Survey Respondent (S552)
Onion Lookups Suggest Typos or Phishing
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hydraruzxpnew4af.onion
hydraruzxpnew3af.onion
Onion Lookups Suggest Typos or Phishing
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hydraruzxpnew4af.onion
hydraruzxpnew3af.onion
529 occurrences in DNS dataset
2 occurrences in DNS dataset
Onion Lookups Suggest Typos or Phishing
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hydraruzxpnew4af.onion
hydraruzxpnew3af.onion
529 occurrences in DNS dataset
2 occurrences in DNS dataset
Unique, correctly-formatted onion domains
Jaro-Winkler similarity score
Weight results by frequency
Onion Lookups Suggest Typos or Phishing
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Onion Lookups Suggest Typos or Phishing
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Russian Market
DuckDuckGo
The Hidden Wiki
Onion Sites are Hard to Verify as Authentic
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Onion Sites are Hard to Verify as Authentic
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Onion Sites are Hard to Verify as Authentic
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Summary of Findings
● Discovering onion services is challenging because they are private by default
● Vanity domains are more memorable but provide a false sense of security
● Users are lacking a way to verify the authenticity of onion domains
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Overview
1. Onion Services Background + Features2. Methods3. Results
a. Onion Sites Discoveryb. Vanity Domainsc. Verifying Onion Sites
4. Future Directions & Conclusions
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Making Onion Domains More Usable
● Make it easier for site foo.com to announce its onion service
● Allow onion service operators to opt-in to publishing mechanism
● Have Tor Browser help with encrypted bookmarks
● Better documentation and education
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ConclusionDespite extra security and privacy properties of onion services, many users are confronted with usability issues
● Susceptibility of onion services to phishing attacks● Discovering the existence of onion services● Managing and remembering onion domains
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ConclusionDespite extra security and privacy properties of onion services, many users are confronted with usability issues
● Susceptibility of onion services to phishing attacks● Discovering the existence of onion services● Managing and remembering onion domains
We can learn from the issues users have encountered to implement design improvements
● Better discovery mechanisms● Better verification mechanisms
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Questions?
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More info at: https://nymity.ch/onion-services/
https://hci.princeton.edu
https://citp.princeton.edu/
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