Re: Reflection DDoS last week

[Denys Fedoryshchenko <nuclearcat () nuclearcat com>]

Hi,

Same happened in Lebanon(country). Similar pattern: carpet bombing for 
multiple prefixes of specific ASN.
I suspect it is a new trend in DDoS-for-hire, and ISP who did not 
install data scrubbing appliances will feel severe pain from such 
attacks, since they use SYN + ACK from legit servers.


On 2019-08-21 22:44, Töma Gavrichenkov wrote:
> Peace,
>
> Here's to confirm that the pattern reported before in NANOG was indeed
> a reflection DDoS attack. On Sunday, it also hit our customer, here's
> the report:
>
> https://www.prnewswire.com/news-releases/root-cause-analysis-and-incident-report-on-the-august-ddos-attack-300905405.html
>
> tl;dr: basically that was a rather massive reflected SYN/ACK carpet
> bombing against several datacenter prefixes (no particular target was
> identified).
>
> --
> Töma
>
> On Sat, Aug 17, 2019, 1:06 AM Jim Shankland <nanog () shankland org>
> wrote:
>
> > Greetings,
> >
> > I'm seeing slow-motion (a few per second, per IP/port pair) syn
> > flood
> > attacks ostensibly originating from 3 NL-based IP blocks:
> > 88.208.0.0/18 [1]
> > , 5.11.80.0/21 [2], and 78.140.128.0/18 [3] ("ostensibly" because
> > ... syn flood,
> > and BCP 38 not yet fully adopted).
> >
> > Why is this syn flood different from all other syn floods? Well ...
> >
> > 1. Rate seems too slow to do any actual damage (is anybody really
> > bothered by a few bad SYN packets per second per service, at this
> > point?); but
> >
> > 2. IPs/port combinations with actual open services are being
> > targeted
> > (I'm seeing ports 22, 443, and 53, just at a glance, to specific IPs
> >
> > with those services running), implying somebody checked for open
> > services first;
> >
> > 3. I'm seeing this in at least 2 locations, to addresses in
> > different,
> > completely unrelated ASes, implying it may be pretty widespread.
> >
> > Is anybody else seeing the same thing? Any thoughts on what's going
> > on?
> > Or should I just be ignoring this and getting on with the weekend?
> >
> > Jim
>
>
> Links:
> ------
> [1] http://88.208.0.0/18
> [2] http://5.11.80.0/21
> [3] http://78.140.128.0/18