BOSTON, July 30, Tor, the Internet privacy
protecting service, said on Wednesday it discovered a compromise
on its network that indicated somebody was trying to monitor the
activity of its users.
"While we don't know when they started doing the attack,
users who operated or accessed hidden services from early
February through July 4 should assume they were affected," Tor
said in a blog entry.
Tor is an anonymity tool designed to protect the identity of
Internet users by routing traffic through multiple nodes around
the globe. It is used by human rights activists, criminals and
others looking to evade surveillance.
The blog post said that it was not sure how much information
the attackers were able to obtain in their efforts to monitor
traffic on Tor.
It advised users to upgrade to the latest version of its
software, which addresses the vulnerability that the attackers
had exploited in this particular case, but said that may not
guarantee the anonymity of users.
"Remember that preventing traffic confirmation in general
remains an open research problem," the blog said.
Tor revealed details of the attack after researchers at
Carnegie Mellon University said they had developed a method of
identifying hundreds of thousands of Tor users.
Those researchers had planned to detail their technique at
next week's Black Hat hacking conference in Las Vegas. The
university canceled the talk after Tor developers complained to
Leaked National Security Agency documents show that the NSA
has logged the IP addresses of many Tor users and may have
scanned emails for users living outside of the United States and
its four closest intelligence allies, German media reported
earlier this month.
(Additional reporting by Joseph Menn in San Francisco; Editing
by Bernadette Baum)