The National Security Agency has made repeated attempts to
develop attacks against people using Tor, a popular tool designed to protect
online anonymity, despite the fact the software is primarily funded and promoted
by the US government itself.
Top-secret NSA documents, disclosed by whistleblower Edward
Snowden, reveal that the agency's current successes against Tor rely on
identifying users and then attacking vulnerable software on their computers.
One technique developed by the agency targeted the Firefox web browser used
with Tor, giving the agency full control over targets' computers, including
access to files, all keystrokes and all online activity.
But the documents suggest that the fundamental security of
the Tor service remains intact. One top-secret presentation, titled 'Tor
Stinks', states: "We will never be able to de-anonymize all Tor users all
the time." It continues: "With manual analysis we can de-anonymize a
very small fraction of Tor users," and says the agency has had "no
success de-anonymizing a user in response" to a specific request.
Another top-secret presentation calls Tor "the king of
high-secure, low-latency internet anonymity".
Tor – which stands for The Onion Router – is an open-source
public project that bounces its users' internet traffic through several other
computers, which it calls "relays" or "nodes", to keep it
anonymous and avoid online censorship tools.
It is relied upon by journalists, activists and campaigners
in the US and Europe as well as in China, Iran and Syria, to maintain the
privacy of their communications and avoid reprisals from government. To this
end, it receives around 60% of its funding from the US government, primarily
the State Department and the Department of Defense – which houses the NSA.
Despite Tor's importance to dissidents and human rights
organizations, however, the NSA and its UK counterpart GCHQ have devoted
considerable efforts to attacking the service, which law enforcement agencies
say is also used by people engaged in terrorism, the trade of child abuse
images, and online drug dealing.
Privacy and human rights groups have been concerned about
the security of Tor following revelations in the Guardian, New York Times and
ProPublica about widespread NSA efforts to undermine privacy and security
software. A report by Brazilian newspaper Globo also contained hints that the
agencies had capabilities against the network.
While it seems that the NSA has not compromised the core
security of the Tor software or network, the documents detail proof-of-concept
attacks, including several relying on the large-scale online surveillance
systems maintained by the NSA and GCHQ through internet cable taps.
One such technique is based on trying to spot patterns in
the signals entering and leaving the Tor network, to try to de-anonymise its
users. The effort was based on a long-discussed theoretical weakness of the
network: that if one agency controlled a large number of the "exits"
from the Tor network, they could identify a large amount of the traffic passing
through it.
Read more at:
No comments:
Post a Comment