Bad data flooding

[Grinch]

This has been recognized by some tracker admins of a very popular tracker. However, since BT works a little bit differently than WinMX it doesn't work. Here is the report:

Two new TV show files on a well known BT tracker - with an excellent record for providing stable trackers and reliable files - have suffered an apparent attack by hackers or an anti-piracy group. Large numbers of clients joined the swarm for these files, and pumped out massive amoutns of bad data. On the file I'm currently downloading, I've so far received around 85% of a 350mb file in almost 24 hours (I'm on 8mb download, so normally get a file this size complete in around 1hr), but 875mb of bad data.

This looks to me like a very effective way to block BT from working - just find copies of the files you want to 'protect' and flood the swarm with corrupted data. It's also similar in part to how anti-piracy groups have attacked Kazaa and similar p2p networks. As the bad data is coming from large numbers of sources, and any BT client must download at least one chunk before banning the sending client for hash fails, this could be very difficult to protect ourselves against.

Before anyone elses asks, I;ve verified this is happening to large numbers of users, and that it is not, as far as the operators of the site can tell - and again, they are very good - a problem with the torrents, the tracker, or the original files. People who have managed to complete the download* vertify that the files do work once complete. The reason I haven't named the group involved or the files is because I don't want to undermine their well deserved reputation in the community. I've posted this in VIP, rather than the member forums, both to protect this reputation, and to ensure it reaches an audience who can comment usefully on this problem.

Sadly, I suspect this may be someone testing this method in preparation for a much larger attack on the BT community. If anyone has any useful comments (i.e., not 'OMG the MPAA suxors) or suggestions for how to avoid this, I'd welcome them.

One thing that you can do if you find a swarm that you are downloading from is hit by an attack of this nature is to make sure that you upload as much good data as possible, to counter-balance the bad data that is being added to the swarm.

But the way clients respond to receiving bad data helps. Like the person suggested, the more good data uploaded the better off.

[Freezmizer]

Sadly, I suspect this may be someone testing this method in preparation for a much larger attack on the BT community.

I have the same suspicion as this guy, I figured it was possible and now it seems inevitable.

But the way clients respond to receiving bad data helps. Like the person suggested, the more good data uploaded the better off.

Agreed, Azureus just dumps bad data and if enough occurences happen then it will automatically ban the IP of the sender. I don't know how other clients handle this.
It may kill your ratio if you keep getting data counted against you even if its bad. But there are more important things than ratios.

[Grinch]

I usually seed 1:1 just because, i may change that to 2:1 just to help out.

Other clients do exactly as Azureus does. Hopefully, BT Client makers take this in consideration when creating their next builds.