Bugtraq mailing list archives
Re: recursive DNS servers DDoS as a growing DDoS problem
From: Jim Pingle <jim () hpcisp com>
Date: Tue, 04 Apr 2006 18:09:02 -0400
Geo. wrote:
We have done just this (block inbound udp/53) to certain subnets due to a rash of CPEs that happily proxy DNS, including recursive queries, from their WAN side.What devices? Is this a default or something customers are configuring?
Just about every Siemens/Efficient *DSL router (5851, 5871, 5890, some others) I have seen does this by default. During one attack I logged into a router and changed the DNS servers used for DHCP from both, to one, to the other, and watched its traffic flow exactly where I pointed the DNS servers. These routers also have a bad habit of hijacking DNS requests for anything in the form of <routername>.anydomain.com. Even if the DNS request is sent to an ISP name server, it will still return a record pointing to its own LAN IP when queried for, i.e. foo.bork.com and foo.microsoft.com if you named the router "foo". It's not only done by default, it's not a configurable behavior as far as I've been able to find. The fix we were supplied with was to block inbound udp/53 using the router's internal IP filtering, and to name the router something unique (i.e. a customer's order number). Jim
Current thread:
- Re: recursive DNS servers DDoS as a growing DDoS problem Gadi Evron (Apr 01)
- <Possible follow-ups>
- RE: recursive DNS servers DDoS as a growing DDoS problem gboyce (Apr 01)
- RE: recursive DNS servers DDoS as a growing DDoS problem Geo. (Apr 03)
- Re: recursive DNS servers DDoS as a growing DDoS problem Jim Pingle (Apr 04)
- RE: recursive DNS servers DDoS as a growing DDoS problem Geo. (Apr 04)
- Re: recursive DNS servers DDoS as a growing DDoS problem Jim Pingle (Apr 09)
- Re: recursive DNS servers DDoS as a growing DDoS problem Erwan David (Apr 09)
- RE: recursive DNS servers DDoS as a growing DDoS problem Geo. (Apr 03)
- Re: recursive DNS servers DDoS as a growing DDoS problem Anton Ivanov (Apr 03)
- Re: recursive DNS servers DDoS as a growing DDoS problem Geo. (Apr 03)
- Re: recursive DNS servers DDoS as a growing DDoS problem Anton Ivanov (Apr 04)
- Re: recursive DNS servers DDoS as a growing DDoS problem Tim (Apr 04)
- Re: recursive DNS servers DDoS as a growing DDoS problem Anton Ivanov (Apr 04)
- Re: recursive DNS servers DDoS as a growing DDoS problem Tim (Apr 04)
- Re: recursive DNS servers DDoS as a growing DDoS problem Ross Wheeler (Apr 09)
- Re: recursive DNS servers DDoS as a growing DDoS problem Anton Ivanov (Apr 09)