They often do this (a) to hide and redirect attribution for these bad things if they are discovered, and (b) to avoid being banned by various blacklists. Like parasites, they hijack someone else’s address space, exploit it for awhile, and then move on.
Doug has observed two concerning trends. First, criminals’ assumptions are not always correct about how “unused” the address space is. A seemingly unused space can be used once in awhile, like the APRICOT network that is only used about four weeks a year. But when this usage clashes with a hijacking the impact can be severe, leading to a massive denial of service on the network.
A second trend is that criminals are getting better at hiding. Not only announcing others’ space, but also forging the AS path – a BGP attribute showing networks that routing information passed through to get to a specified router. This forged path shows the correct origin for the announced address space, so it is hard to detect and hard to filter out.
The good news is that incidents like this can be spotted and prevented if more networks begin watching more carefully what their customers are announcing. And the more networks do that, the fewer opportunities there are for criminals to exploit the global routing system, undermining its stability and security.
The MANRS actions are aimed exactly at that. MANRS defines a new industry norm for routing security that will to a great extent prevent incidents like this and improve confidence in the routing system of the Internet.
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