August 09, 2013 | Lee Maguire

Website blocking measures lead to inadvertent censorship

A technical decision made by Sky in implementing website blocking has lead to the blocking of news site TorrentFreak

TorrentFreak reports today that Sky is currently blocking access to their site. Not as a deliberate act of censorship, but as an entirely predictable by-product of its system for complying with court-ordered website blocks.

When the owner of EZTV (a site ordered blocked on the 25th of July) automatically pointed UK visitors to, Sky's blocking system (which from court documents we believe to be codenamed "Hawkeye") apparently automatically added TorrentFreak's IP address to its blacklist.

Inadvertent denial-of-service by pointing DNS records at innocent third-parties is an entirely predictable possibility for anyone attempting to implement blocking systems. If this explanation for blocking proves to be the case, we'd be extremely surprised if the possibility had not occurred to the engineers responsible.

Open Rights Group continues our call for more transparency in the ways these blocks are performed, including access to the orders that would presumably limit the legal scope of blocking. If merely blocking the handful of sites that have received blocking orders in the past 12 months results in collateral damage (such as the blocking of we hold little confidence in the ISPs being able to implement David Cameron's default network filtering plans without causing significant disruption.

Comments (4)

  1. Paul Hatch:
    Aug 09, 2013 at 04:12 PM

    This is a massive security flaw. While it may have been discovered inadvertently, the havoc that could be caused if used maliciously is immense. Let's face it the blocked site owners have motive and could potentially block any site of their choosing to 4m sky broadband users.

  2. Paul:
    Aug 09, 2013 at 05:40 PM

    There are some great comments below the line on the Torrentfreak website wondering what would happen if EZTV redirected to Sky's DNS addresses.
    The list of hilarious possibilities seems endless -,,, ...

  3. Paul Hatch:
    Aug 09, 2013 at 10:13 PM

    The security flaw occurred because sky were lazy and tried to put a stop to the predictable game of ip address whack a more and we're too clever by half trying to dynamically update their ip blacklist whenever their dns refreshed. If I recall they even boasted that their system would now automatically update to account for ip changes. Not feeling so clever now are they.

    While TF plays down the effect to their site, you can bet this info is going round the blocked site admits who are bound to have fun with it. Sky seem to be trying to keep it low key by avoiding public acknowledgment of the flaw. They will have to go back to maintain their blocks by hand so let the whack a more recommence.

  4. Simon:
    Aug 15, 2013 at 02:09 PM

    Had eztv known about this they should have made it so that bbc, google, yahoo, facebook or some other popular domain was targeted instead of torrentfreak. Would have got the point across much faster.