[ISN] Last month's root-server attack revisited

From: InfoSec News (alerts@private)
Date: Fri Mar 09 2007 - 00:04:32 PST


By Dan Goodin in San Francisco 
9th March 2007

Last month's attack on at least six of the net's root servers was 
formidable, but thanks to the implementation of a technology designed to 
protect the infrastructure, only two were affected, according to a 
factsheet [1] issued today by ICANN.

The DDoS attack flooded the servers with a stunning amount of data, as 
much as 1 Gbps at points, according to the oversight group. But damage 
was relatively contained thanks to new load-balancing technology called 
Anycast, which was installed on all the servers that came under fire, 
except for the two that sustained damage.

"Anycast allows a number of servers in different places to act as if 
they are in the same place," according to the document. "So while there 
remains 13 locations on the network for root serves, the reality on the 
ground is that not only are there often dozens at one spot but dozens of 
servers in other locations that can also deal with requests."

That allows the servers - which translate domain names such as 
theregister.com into IP numbers such as - to distribute 
large volumes of data evenly among many machines (a 
many-hands-make-light-work approach, if you will). Anycast also 
safeguards against damage that could be caused by natural disasters by 
geographically dispersing servers.

The attack was, in fact, two forays, one that started at 4AM California 
time on Feb. 6 and lasted for two-and-a-half hours, and the other, a 
five-hour assault that started several hours after the first one 
stopped. That torrent of packets originated from hundreds of zombies, so 
it's impossible to know where in the world the attackers were located. 
Educated guesses lead engineers to believe they came from the Asia 
Pacific, possibly in Korea.

Of the two servers that sustained damage, one was the g-root, which is 
operated by US Department of Defense and is physically located in Ohio, 
and the other was the l-root, run by ICANN and based in California. 
ICANN attributed the damage they sustained to the absence of Anycast.

In addition to those two root servers, three others also are not using 
the technology. Engineers have held off installing it universally 
because the root servers run on many different OSes, including Windows 
(gulp), Linux, MacOS X NetWare, Unix and OS/2, making it impractical to 
run the software on all of them. Engineers also resisted installing it 
everywhere because some worried there could be risks associated with 
making different servers appear to be coming from the same place.

After last month's episode, it's likely the remaining servers - which in 
addition to roots G and L also include roots D, E and H - will adopt the 
technology soon.

[1] http://icann.org/announcements/announcement-08mar07.htm

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