Would you mind explaining this piece of the story in a little more detail?

"When the attackers stumbled upon this, probably by accident, it resulted in a lot of bogus traffic being injected into the IXP fabrics in an unusual way, until the IXP operators were able to work with everyone to make certain the IXP IP blocks weren't being globally re-advertised."

It's pretty fascinating and I think most of the HN audience, myself included, would be able to understand the actual technical detail.