GitHub has been hit with the largest-ever DDoS attack, and it was only down for a few minutes:
On Wednesday, February 28, 2018 GitHub.com was unavailable from 17:21 to 17:26 UTC and intermittently unavailable from 17:26 to 17:30 UTC due to a distributed denial-of-service (DDoS) attack.
[...] Cloudflare described an amplification vector using memcached over UDP in their blog post this week, "Memcrashed - Major amplification attacks from UDP port 11211". The attack works by abusing memcached instances that are inadvertently accessible on the public internet with UDP support enabled. Spoofing of IP addresses allows memcached's responses to be targeted against another address, like ones used to serve GitHub.com, and send more data toward the target than needs to be sent by the unspoofed source. The vulnerability via misconfiguration described in the post is somewhat unique amongst that class of attacks because the amplification factor is up to 51,000, meaning that for each byte sent by the attacker, up to 51KB is sent toward the target.
[...] Between 17:21 and 17:30 UTC on February 28th we identified and mitigated a significant volumetric DDoS attack. The attack originated from over a thousand different autonomous systems (ASNs) across tens of thousands of unique endpoints. It was an amplification attack using the memcached-based approach described above that peaked at 1.35Tbps via 126.9 million packets per second.
Also at Wired and The Register.
(Score: 2) by bob_super on Friday March 02 2018, @05:56PM
You could imagine a protocol where the first packets you receive from a brand-new return IP range get challenged before being forwarded. If the sender pretending to be at that address doesn't respond to a challenge, you discard. The challenge has to be a small packet, on the edge of the network (a tiny ping), to avoid adding congestion.
That wouldn't stop state-sponsored attacks, but script kiddies playing with Memcached would be limited to bugging their neighbors.