Anonymity Systems: Tor

Overview
Anonymity systems
Review of how Tor works
Tor Project Inc.
Helper tools and accessories
Advanced Tor control
Attack Vectors

Anonymity Systems
JAP
I2P
Freenet
Xerobank
Botnets

Freenet
Storage network p2p based
Shares files on your system to other nodes
Plausabile Deniability

I2P
Opposing design of Tor
UDP based
Darknet design
Java, Python, and C API’s
Mixed routing based on packets
Splits tunneling between upstream and downstream
“Garlic Routing” – mix streams together to prevent traffic analysis
Variable latency design

Tor
Tor (not TOR) – previously stood for The Onion Router
Provides a method of anonymity by passing data between proxies

Tor Network

Terminology
Cell – your message
Circuit – tunnel made up of relays
Entry Node: first hop into the Tor network
Exit Node: last hop before destination
Relay Node: middle hop
Bridge Node: nodes not listed in the Tor directory to evade filtering

Who’s Using Tor?
Whistleblowers
Wikileaks – runs hidden service
Militaries
field ops
command and control using hidden services
Chinese journalists and dissidents

Tor Project
501(c)(3) NFP
Freely available
Full spec and full documentation

Project Finances
https://www.torproject.org/about/financials.html

Current Project Sponsors
Federal Grant:
International Program to Support Democracy Human Rights and Labor
$632,189
International Broadcasting Bureau
Voice of America, Radio Free Europe/Radio Liberty, Radio and TV Martí, Radio Free Asia, Radio Sawa/Alhurra TV
$270,000
Stichting.Net
Association of NFP’s in the Netherlands
$38,279
Google: $29,083
ITT: $27,000
Other: $9,997
https://www.torproject.org/about/sponsors.html.en

Past Funders
DARPA and Naval Research Labratory 2001-2006
EFF – 2004-2005

Tor Performance

Number of Relays

Number of Users

Tor Tools
Torbutton
Tor Browser Bundle
Vidalia
TorCheck
Arm
Tor-ramdisk
Anthony G. Basile from Buffalo

Tor Control Port
authenticate "“
extendcircuit 0 a,b,c,…
extendcircuit 0 a,b
seteventscirc
setconfconfitem
Mapaddress google.com=a.b
Getconfconfitem
Telnet to the control port
Create custom circuits (long or short)
Show live circuit information
Change configuration on the fly
Map a site to an exit node
Reload a configuration

Attacks

Tor Passive Attack Vectors
Traffic profiling – entry and exit analysis
Cleartext exit node transmission
Fingerprinting - OS, browser, configuration, activity
Timing correlation
Network partitioning
End to end Size correlation

Tor Active Attack Vectors
Compromised keys
Malicious web servers
Malicious Exit/Relay nodes
DoS non-controlled nodes
Timestamping and tagging
Injecting or replacing unencrypted info
Malicious Tor client

Tor Client Side Attacks
DNS rebinding
Disbanding attack – javascript, java, flash
History disclosure
Timezone information (partitioning)

Social Engineering Attacks
Getting more traffic
“Use my relay. I have huge tubes!”
“Nick’s relay sucks”
“I’ve added a feature to my node.”
Replacement
“Tor rapes babies. Use my software.”
Partitioning
“Don’t use servers from this country”
“These servers are amazing!”

More Info
www.torproject.org
Metrics.torproject.org
Blog.torproject.org
Check.torproject.org
@torproject

Anonymity Systems: Tor

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