The National Security Agency has been waging a campaign to unmask the users of the anonymous Internet tool Tor, the Washington Post reports.
According to documents provided by former NSA contractor Edward Snowden, the agency has been developing capabilities — and some of them highly successful — to identify terrorists using the countersurveillance tool.
Tor was developed by the U.S. Naval Research Laboratory, and although it is managed by a private non-profit foundation, still receives funding from the federal government, including from the State Department.
For political dissidents, journalists, and privacy advocates, the NSA’s activities mean that even their own attempts to evade detection are noticed, and sometimes foiled by the agency.
“In some cases, the NSA has succeeded in blocking access to the anonymous network, diverting Tor users to insecure channels,” reports the Washington Post.
“With a tool called MJOLNIR — the name of the hammer used by Thor, the Norse god of thunder — it has been able to monitor and control the paths of communications that are supposed to be chosen randomly as they pass through Tor,” said the publication.
“Another operation, called MULLENIZE, can “stain” anonymous traffic as it enters the Tor network, enabling the NSA to identify users as it exits,” said the news organization.
The agency recognizes Tor’s legitimate use by dissidents, claiming to engage in the targeting of terrorist and foreign intelligence threats, but its techniques have also been employed by the Federal Bureau of Investigation to nab cyber criminals.
Initial reports from Snowden’s revelations about the agency’s Internet surveillance suggest that the NSA will also specifically try to identify Internet users employing countersurveillance measures and privacy protection techniques.