SNMP DDoS: the vulnerability you might not know you have

Blake Dunlap ikiris at
Wed Jul 31 21:29:18 UTC 2013

I bet blocking all SYN packets and non related flow UDP packets to
customers would be even more effective. Why don't we do that and be done
with it instead of playing whack a mole every 3 months when someone finds
some new service that was poorly designed so that it can be used to send a

Yes, I'm being sarcastic above.

This is hardly the first finger of death amplification attack, and I
strongly doubt it'll be the last. Years ago it was smurf, then Quake
servers, then DNS, then Battlefield boxes, etc etc. Now it seems to be snmp
and recently chargen, and tomorrow it'll be some peer 2 peer service, the
next day it'll be a voice app. It will never end, and breaking the internet
port by port doesn't do anything to make it better.

I've been the victim of week long DDoS attacks that took down our
upstreams, not to mention us, and I still maintain the above.

It works better to fix the design issues than to play whack a mole by
blocking every imaginable service to your customers that responds to the
public with data larger than a FIN. Like getting their providers to more
proactively police their spew, manufactures to stop making negligent
devices, or implementing more intelligent filter communication so the only
option doesn't begin with calling your provider and asking them over the
phone to block X ip for you since you're off the internet.

Maybe even look into liability laws for allowing said attacks to originate
from your customers and not doing anything about it, or being manufacturer
of said devices that harm others through their lack of due diligence
implementing proper security. It's still way more effective than trying to
fix the *last instance* of the problem, instead of it's reasons for
enduring as an issue at a global scale.


On Wed, Jul 31, 2013 at 3:46 PM, Dobbins, Roland <rdobbins at> wrote:

> On Aug 1, 2013, at 3:11 AM, bottiger wrote:
> > The most disturbing part is the lack of logging.
> Flow telemetry can be of use in this instance.
> -----------------------------------------------------------------------
> Roland Dobbins <rdobbins at> // <>
>           Luck is the residue of opportunity and design.
>                        -- John Milton

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