- Feb 7, 2014
- 1,540
Researchers have revealed a new vulnerability in the design of Tor, the world’s favourite weapons-grade privacy tool.
In their presentation, Non-Hidden Hidden Services Considered Harmful, given at the recent Hack in the Box conference, Filippo Valsorda and George Tankersley showed that a critical component of the Dark Web, Tor’s Hidden Service Directories (HSDirs), could be turned against users.
Targeting HSDirs is so easy that the researchers suggest you should avoid the Dark Web if you really care about your anonymity.
According to Valsorda and Tankersley:
Hidden service users face a greater risk of targeted deanonymization than normal Tor users … It would probably be better to let them use Tor on your TLS-enabled clearnet site.
To understand how the vulnerability works and how it chips away at Tor’s armour we need to start by looking at how Tor works and how it’s been attacked in the past.
How Tor works
Tor (AKA The Onion Router) is software that provides computers with privacy protection and anonymity.
It can be used to access the regular internet anonymously, or the so-called Dark Web where sites and services (recognisable by addresses ending in .onion) also enjoy Tor’s protection.
Tor works by routing your traffic through a handful of computers, called a circuit, that use encryption to hide your IP address from the site or service you’re talking to. The computers in your circuit, called relays, are chosen at random from a global pool of around 7,000 computers that act as Tor nodes.
Network packets are wrapped in multiple layers of encryption and sent to their destination via your circuit. Each relay in the circuit peels back one layer of encryption, revealing the address of the next relay.
Since each relay only knows about the relay before and after it, no computer in the circuit knows both the ultimate origin and destination of your traffic.
The first relay in the circuit is known as the entry guard and the last as the exit node.
That exit node (which could be anywhere in the world) is where your traffic appears to come from. It’s also a prime location for spying on or deanonymising Tor users accessing the regular internet.
If you use Tor to access the Dark Web then your traffic passes through two circuits, one established by you and another established by the .onion site you’re using, and the two circuits meet at ‘rendezvous point’ in the middle.
You can catch the rest of this news here: Can you trust Tor’s hidden service directories?
In their presentation, Non-Hidden Hidden Services Considered Harmful, given at the recent Hack in the Box conference, Filippo Valsorda and George Tankersley showed that a critical component of the Dark Web, Tor’s Hidden Service Directories (HSDirs), could be turned against users.
Targeting HSDirs is so easy that the researchers suggest you should avoid the Dark Web if you really care about your anonymity.
According to Valsorda and Tankersley:
Hidden service users face a greater risk of targeted deanonymization than normal Tor users … It would probably be better to let them use Tor on your TLS-enabled clearnet site.
To understand how the vulnerability works and how it chips away at Tor’s armour we need to start by looking at how Tor works and how it’s been attacked in the past.
How Tor works
Tor (AKA The Onion Router) is software that provides computers with privacy protection and anonymity.
It can be used to access the regular internet anonymously, or the so-called Dark Web where sites and services (recognisable by addresses ending in .onion) also enjoy Tor’s protection.
Tor works by routing your traffic through a handful of computers, called a circuit, that use encryption to hide your IP address from the site or service you’re talking to. The computers in your circuit, called relays, are chosen at random from a global pool of around 7,000 computers that act as Tor nodes.
Network packets are wrapped in multiple layers of encryption and sent to their destination via your circuit. Each relay in the circuit peels back one layer of encryption, revealing the address of the next relay.
Since each relay only knows about the relay before and after it, no computer in the circuit knows both the ultimate origin and destination of your traffic.
The first relay in the circuit is known as the entry guard and the last as the exit node.
That exit node (which could be anywhere in the world) is where your traffic appears to come from. It’s also a prime location for spying on or deanonymising Tor users accessing the regular internet.
If you use Tor to access the Dark Web then your traffic passes through two circuits, one established by you and another established by the .onion site you’re using, and the two circuits meet at ‘rendezvous point’ in the middle.
You can catch the rest of this news here: Can you trust Tor’s hidden service directories?
