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> There are estimates that the Dyn attack was 1.2Tbps. What provider do you work for that can absorb that? I work for F5 Silverline. It would be naive to brus
by gbuk2013 10y ago
> There are estimates that the Dyn attack was 1.2Tbps. What provider do you work for that can absorb that?
I work for F5 Silverline.
It would be naive to brush off that size of attack as it would stress any DDoS mitigation provider.
We have the capacity to take it (and are adding a lot more in the coming months precisely because of attacks like this and the previous big one that hit Brian Kerbs) but you would have to talk to Sales about what sort of guarantees we would be willing to provide.
That said, at least that would be our problem, since we would have to pay for the bandwidth consumed - not the customer! ;)
> Does scrubbing work with a bunch of randomized source ports and source address? How do you find the "signature" in that to scrub? It was my understanding that the traffic in the Dyn attacks was indistinguishable from legitimate traffic. Can you explain how traffic scrubbing works in such scenarios? Or do you just drop stuff on the floor?
(Answer from one of my more knowledgeable colleagues since I work on supporting the infrastructure rather than DDoS mitigation itself):
Most attack traffic has a signature of its behaviour beyond source IP and port.
For simple flood attacks, connection rate-limiting per source IP is very effective. Typically there are some simple firewall rules that will work too, especially with attacks generated against targets that don’t support the attack vector (e.g. block all GRE traffic coming to your website which is only TCP 80/443).
If the attack is operating at L7, there are additional fingerprinting methods we can use around HTTP headers, intelligent rate-limiters, JavaScript injection to prove an actual human, etc.
- bogomipz 10y agoThanks for the response. I didn't know F5 had such an offering, I will certainly check it out. ">For simple flood attacks, connection rate-limiting per source IP is very effective." But if a each of the 8 million bots in a hypothetical botnet sends exactly one syn packet then you can't really rate limit per source IP. Or the case of DNS a single UDP datagram which might be indistinguishable from a "legitimate" DNS query datagram. Also rate limiting is different that what I would think of as "scrubbing" unless I am thinking about scrubbing wrong. Back to my example of the botnet where the command and control tells each node to send a single packet or a small handful of packets towards a destination, theres very limit match a rate limit filter on in that case no?
- gbuk2013 10y agoI think "rate limiting" is used as an indicator of malicious intent rather than in the QoS sense. If we classify traffic as malicious we drop it. The single SYN will fail the 3WHS test, so we would drop it. For DNS we can usually fingerprint the attacker and block traffic. Because we are a full proxy we can do packet inspection as well. ;) There's a fair amount of intelligence already built into our products which we of course make use of (BIG-IP LTM/AFM/ASM, "IP Intelligence"). Eventually it may well come down to the SOC monitoring and adjusting the filters in real time as required - that's life.