Facebook temporarily blocks access from Tor

Posted by   Virus Bulletin on   Jun 19, 2013

Malicious activity triggered automatic lockdown.

A 'high volume of malicious activity across Tor exit nodes' is believed to have been the reason why Facebook temporarily blocked access through Tor - an issue that has since been resolved.

Tor is software that provides online anonymity by making Internet traffic pass through a number of nodes before reaching its final destination. Because the way the various connections are encrypted, none of the nodes can view both the source and the destination address at the same time.

Tor is popular among privacy activists, as well as opposition members living under oppressive regimes, who use it both to anonymously communicate with each other and to bypass surveillance. The recent revelations of the PRISM surveillance network operated by the NSA is likely to give Tor's use a boost.

Security researchers are also frequent users of Tor, for instance to hide their location when investigating malicious activity on the Internet. But there is a third group that frequently uses Tor: cybercriminals. Because the destination cannot distinguish between different users of the Tor network, the crooks not only prevent their real IP address from being known, they reduce the chances of their activity being blocked.

Unless, of course, malicious activity from the Tor network becomes so bad that the destination service cannot but block access from all nodes. This is what has happened at Facebook. Although technical details have not been made public, it is generally possible to distinguish between traffic coming from Tor and other Internet traffic.

Tor is a great service for enabling online anonymity. For some, it could make doing their job a little easier; for others using Tor could be a matter of life and death. But for the security community it also provides new challenges.

For those wanting to visit Facebook using Tor there is good news: access has been restored.

Posted on 19 June 2013 by Martijn Grooten



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