[tor-talk] German BND 2010: Tor Unsuitable
grarpamp at gmail.com
Thu Sep 21 15:25:14 UTC 2017
A global passive adversary
Like all low-latency anonymity systems used in practice, Tor cannot
protect against „a global passive adversary“. This is defined in the
design document. The software documentation warns: „If your attacker
can watch the traffic coming out of your computer, and also the
traffic arriving at your chosen destination, he can use statistical
analysis to discover that they are part of the same circuit.“ The goal
of NSA’s and GCHQ’s internet surveillance is to achieve exactly that.
A number of researchers have demonstrated this attack in practice,
either by simply counting transmitted packets, by analyzing time
windows, or correlation attacks with only a fraction of traffic. All
this research is public. The spy agencies followed this research, used
it for their own purpose and turned theoretical vulnerabilities into
real-world surveillance systems.
Very high level of surveillance
One and a half years later, the BND warned German federal agencies not
to use Tor. The hacker unit „IT operations“ entitled its report: „The
anonymity service Tor does not guarantee anonymity on the internet“.
The six-page paper was sent to the chancellery, ministries, secret
services, the military and police agencies on 2 September 2010.
According to the executive summary, Tor is „unsuitable“ for three
scenarios: „obfuscating activities on the internet“, „circumventing
censorship measures“ and „computer network operations for intelligence
services“ – spy agency hacking. The BND assumes „a very high level of
surveillance within the network“
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