> On Aug 19, 2021, at 4:05 PM, Pirawat WATANAPONGSE via NANOG <nanog@nanog.org> > wrote: > Background Information Part: > We rent an IP Address Block and a DNS zone. > [We have to pay the annual fees, so they are renting, yes? :-) ]
We don’t have enough information to know whether you’re renting or are the
registrant, based on what you’ve said.
If you receive your domain name from a registrar, and the whois shows you to be
the registrant, you’re the registrant. If you have a subdomain or you pay
“rent” to someone who is shown as the registrant in the whois, then you’re just
renting.
Likewise, if you receive your IP addresses from a regional Internet registry
(ARIN in the NANOG region), you’re the LIR, or Local Internet Registry. If you
have a subnet (which may be SWIPped into the whois, or may not) which you
received from an LIR, then you’re just renting.
> We run our own DNS authoritative server, with DNSsec on.
Meaning that you’re DNS signing both the forward (A/AAAA) and reverse
(in-addr/ip6) zones?
> Authority over DNS records, ROAs, and BGP table are with us, but authority
> over the Web Servers are (naturally) not.
It’s not clear what you mean by this. You mean that you don’t operate your own
web servers, but instead use an outsourced service, which in turn uses its own
IP addresses?
> Question Part:
> 1. How (or where) can I monitor/control such that no one can ‘map’ my IP
> addresses to external FQDNs [hijacking my IPs] without me knowing about it?
These are separate and unrelated things.
Hijacking your IP addresses would be originating BGP announcement of them.
Which other people should not do, and other people should not pay attention to
if they’re validating ROAs and IRR entries.
Mapping your IP addresses to domain names (in-addr/ip6) is not an effective
attack vector, and nobody will pay attention to anyway, if you’re the
authoritative delegate for those blocks.
Mapping domain names to IP addresses (A/AAAA) is not an effective attack
vector, and anyone can do, without disrupting anything.
> 1.1. My understanding is that, as long as I control the authoritative
> (DNSsec)server and people out there validate the DNS responses, hijacking my
> IPs outright for use somewhere else is (theoretically) impossible, yes?
If someone else conducts an effective DNS hijacking attack, intermediating
themselves between your users and your servers, and your users don’t DNSSEC
validate, then the attack will be successful. If your users do DNSSEC
validate, AND THE APPS AND OSES THEY USE DON’T CIRCUMVENT IT, then the attack
will fail. But that’s a big if. Many apps and OSes prefer a MITM attacker to
a DNSSEC validation failure, because support costs.
> 2. But, web admins can still essentially ‘rent out’ part or whole of my
> websites by hosting 'forreign' pages/codes and allowing in ‘external
> redirection’ from outside (to use my hardware! my IPs!) anyway, yes?
If by “web admins” you mean third parties, rather than people who are
responsible to you, yes. Which is why people concerned with security host
their own services.
> 3. How (or where) can I monitor/control such that no one can ‘map’ FQDNs from
> within my DNS zone to external IP addresses [hijacking my hostnames] without
> me knowing about it?
There are at least three possibilities here.
One is that someone has access to the unsigned zone data below your delegation,
in which case this is an internal security problem. If you’re using NSEC3 to
prevent zone enumeration, and it were occurring in a delegated subdomain, this
might actually be a difficult problem.
The second possibility is that someone external to your organization, who has
access to DNS traffic flows (client, recursive, etc.) interposes themselves as
a MITM or injects false data into a resolver cache. You could, hypothetically,
buy access to “passive DNS” feeds which might reveal some portion of such
traffic, if it existed, but that’s a very long shot.
A third (and probably most likely) possibility is that someone hijacks your
domain at the registrar level, because registrars generally have crap security
and fall over all the time, and registrants routinely use crap passwords to
secure their accounts with registrars, etc. They could then add an additional
nameserver, or substitute in all of their own nameservers. At that point,
their actions would be fairly visible, and they’d still have to do a dirty roll
of the DNSSEC KSKs, if they wanted to make things validate, but most wouldn’t
bother doing so. There are monitoring services which watch for nameserver
changes, but all the ones I’ve seen don’t actually check as often as they say
they do, so miss attacks of this sort that are done quickly.
> 3.1. My understanding is that, web admins can write all sorts of ‘redirect’
> in such a way that parts or even my whole websites can be ‘hosted’ on
> external IPs/hardware, yes?
Yep. See “why you shouldn’t do that” above.
> 4. Does that mean I need a big Web Application Firewall (WAF)
Absolutely not. I have no idea what a Web Application Firewall is, but if it’s
anything like it sounds like, I wouldn’t let one anywhere near anything I was
responsible for securing.
> The thing is, no one should be able to use organization resources [IPs,
> FQDNs, and Web Services, for a start] for his/her own purpose without asking
> permission.
Sounds like you’re going to be writing a lot of shell scripts and cron jobs.
Welcome to security. Remember to test your backups, that’s always the most
important thing in any security regime.
-Bill
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