[nsp-sec] DNS amplification attack to 213.171.220.101

[White, Gerard]

I did not realize that!  Thanks for the insight, Florian!

GW
855 - Bell Aliant


-----Original Message-----
From: nsp-security-bounces at puck.nether.net [mailto:nsp-security-bounces at puck.nether.net] On Behalf Of Florian Weimer
Sent: Monday, February 16, 2009 8:03 AM
To: White, Gerard
Cc: NSP nsp-security
Subject: Re: [nsp-sec] DNS amplification attack to 213.171.220.101

----------- nsp-security Confidential --------

* Gerard White:

> Yup.  For practically every DNS speaking device I can find here,
> there's a continuous type 16 (Text Strings) Query for
> "johnmadness.com"...  Query ID's are unique and random.  oddly
> enough there's an additional record present in the queries - a Type
> 41 (Option) (Class 65535).

The OPT pseudo-RR enables clients to request larger UDP packets than
the default 512 bytes.  This way, you can achieve an amplification
factor between 70 and 80 in a reflective attack.

-- 
Florian Weimer                <fweimer at bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99


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