Spoofing ASNs (Re: SNMP DDoS: the vulnerability you might not know you have)

Jared Mauch jared at puck.nether.net
Thu Aug 8 20:37:11 UTC 2013


On Aug 8, 2013, at 2:07 PM, Blake Dunlap <ikiris at gmail.com> wrote:

> On a related note, how are you actually getting this data?

Sure:

https://www.nanog.org/sites/default/files/tue.lightning3.open_resolver.mauch_.pdf

I would point you at the streaming archive, but I'm not sure where they went.  Perhaps they can post them to Youtube?

Anyways, the alternate set of IPs responding is actually increasing over time:

http://openresolverproject.org/breakdown-graph2.cgi

> What you have said previously ( Number of unique IPs that spoofed a packet to me. (eg: I sent a packet to 1.2.3.4 and 5.6.7.8 responded). ) doesn't even make sense.

Many CPE devices will perform NAT on udp/53 packets received on their WAN interface and forward them to their configured DNS server.  Some will just take the source IP and copy it into the packet.  Because it comes in on their WAN interface, it will instead of copying the inside NAT address just copy my source IP from the weekly scan and use that.  Since it's on the outside, it doesn't copy it's outside IP and put that in, it copies mine.

- Jared

> On Thu, Aug 8, 2013 at 12:51 PM, Jared Mauch <jared at puck.nether.net> wrote:
> Oops, I pulled the wrong data (off by one column) out before a trip and didn't realize it until now.
> 
> This is not the spoofer list, but the list of ASNs with open resolvers.
> 
> Let me reprocess it.
> 
> Apologies, corrected data being generated.
> 
> - Jared
> 
> On Aug 8, 2013, at 1:29 PM, Jared Mauch <jared at puck.nether.net> wrote:
> 
> > The following is a sorted list from worst to best of networks that allow spoofing: (cutoff here is 25k)
> >
> > (full list - http://openresolverproject.org/full-spoofer-asn-list-201307.txt )
> 
> 
> 




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