UK's Internet Infrastructure Open to Prying Eyes
Network Penetration
NetworkPenetration.com
Copyright (c) 2003 Ste Jones
root@xxxxxxxxxxxxxxxxxxxxxx
UK's Internet Infrastructure Open to Prying Eyes
DNS Zone Transfers Allowed from First and Second Level Domains
Index
1. Introduction
2. What was tested
3. Example zone transfers
4. Results for UK domains
5. Recommendations
1. Introduction
Network Penetration conducted a survey at the start of 2003 to check the status
of the UK's DNS infrastructure. The second scan of the year has just been
completed with the results are much more positive. There are still some serious
holes in major areas, but much improvement has been made in the last 8 months.
The rest of the paper will discuss what was tested, the results, some sample
zone transfers and finally some recommendations.
2. What was tested
During each scan only one test was performed against each domain:
A full zone transfer (axfr) against the first authoritive DNS server assigned
to that domain.
A zone transfer consists of copying the contents of a zone file from a DNS
server. This normally occurs when a secondary DNS server wishes to replicate
the information for a zone from a primary DNS server for purposes of backup /
redundancy. A zone file consists of all the information about that zone such as
the IP address of a web server or mail server or possibly the hostname and IP
of a firewall. Much of the information is open to request such as what email
server is used for that domain, but other records such as the IP address and
domain name of the firewall should not.
First and second level zones generally do not contain IP addresses of firewalls
and such like, but they do contain huge lists of every subdomain. Take for
example the zone file for the co.uk domain, it would contain every domain with
a co.uk extension.
3. Example Zone Transfers
All the transfers were conducted using free online tools provided by demon.net
3.1 Example one - Secured Domain
A zone transfer from the .biz domain returns in a timeout and no information is
returned
3.2 Example Two - Secured Domain
Where as when trying to zone transfer .mil a connection refused is returned.
Domain: mil.
Primary Nameserver: G.ROOT-SERVERS.NET
E-mail Contact: HOSTMASTER@xxxxxxx
/www/cgi-bin/demon/external/bin/dig @G.ROOT-SERVERS.NET mil. axfr
; <<>> DiG 2.1 <<>> @G.ROOT-SERVERS.NET mil. axfr ; (1 server found)
;; Received 0 records.
;; FROM: nu7www.demon.net to SERVER: 192.112.36.4 ;; WHEN: Tue Aug 12 01:08:14
2003
3.3 Example Three - Unsecure Domain
An unsecured domain however such as fake.com would return the following
Domain: fake.com.
Primary Nameserver: ns1.fakehosting.com E-mail Contact: admin@xxxxxxxxxxxxxxx
/www/cgi-bin/demon/external/bin/dig @ns1.fakehosting.com fake.com. axfr
; <<>> DiG 2.1 <<>> @ns1.netincomehost.com fake.com. axfr ; (1 server found)
fake.com.3600SOAns1.fakehosting.com. admin.fakehosting.com. (
10; serial
3600; refresh (1 hour)
600; retry (10 mins)
1209600; expire (14 days)
3600 ); minimum (1 hour)
fake.com. 3600 A 1.2.3.4
fake.com. 3600 NS ns1.fakehosting.com
fake.com. 3600 NS ns2.fakehosting.com
fake.com. 3600 MX10 smtp.fake.com.
webmail.fake.com. 3600 CNAME webmail.freemail.com.
cisco.fake.com. 3600 A 1.2.3.1
fw1.fake.com. 3600 A 1.2.3.2
snort.fake.com. 3600 A 1.2.3.3
www.fake.com. 3600 A 1.2.3.4
ftp.fake.com. 3600 A 1.2.3.5
pdc.fake.com. 3600 A 1.2.3.6
fake.com. 3600 SOA ns1.fakehosting.com admin.fakehosting.com. (
10; serial
3600; refresh (1 hour)
600; retry (10 mins)
1209600; expire (14 days)
3600 ); minimum (1 hour)
;; Received 10 records.
;; FROM: nu7www.demon.net to SERVER: 64.42.224.9 ;; WHEN: Mon Aug 11 23:20:47
2003
The fuctisous zone file for fake.com shows a whole range of possible targets
that a hacker could use to quickly map a network without having to send hardly
any packets to the network.
The information regarding the top and second level domains are not being
published due to the possibility of them being exploited at some point in the
future.
4. Results for UK DNS Infrastructure
At the start of the year nearly all the second level domains in the UK allowed
a zone transfer, but now its only really sections of the government lagging
behind.
Domain Transfer Possible Number of Records Notes
Jan 03 August 03 Jan 03 August 03
uk Yes yes 220 248
ac.uk no no - -
bl.uk Yes no 1892 -
co.uk no no - -
gov.uk yes no 5 -
govt.uk no no - -
ltd.uk yes no 26723 - Over 1 Mb
me.uk yes no 57329 - Over 1 Mb
mod.uk yes yes 1484 1729
net.uk yes no 1298 -
nls.uk yes no 438 -
org.uk yes no 422265 - Over 20 Mb
plc.uk yes no 3646 -
police.uk yes yes 234 241
sch.uk yes no 71360 - Over 1 Mb
The only test performed against each server was a full zone transfer, some
returned the full zone file while others such as gov.uk only returned a partial
zone file.
In total 15 domains were tested, 3 passed test with transfers not possible at
the start of the year compared to 12 in August. 20% at the start of the year,
80% in August can the UK score a 100% by the end of the year and lock down all
there DNS servers? One would like to think so.
After sending an early copy of this report to various domain administrators,
Network Penetration received a response from Jay Daley Director of IT at
Nominet UK.
"It is our policy that .uk is not closed to zone transfers though all of the
second level domains (SLDs) that we manage are. There are a large number of
people who pull the .uk zone to allow their nameservers fast repudiation of
non-existent SLDs (e.g. when someone types in xxx.com.uk by accident)."
The two remaining zones mod.uk and police.uk may be open for a specific reason
unknown to Network Penetration at this time but upon initial inspection they
appear to be unsecured DNS servers. One possible reason is that zone transfers
are extremely useful for debugging problems with domain name servers.
The information provided in this report does not necessarily mean that each
domain was unsecure / secured but merely gives a rough guide to the state of
the UK's DNS infrastructure.
5. Recommendations
Zone files contain lots of crucial information that a hacker or terrorist could
use to attack a nations infrastructure due to zone files containing information
on a networks design and also highlighting key nodes within a networks
infrastructure. Zone transfers should be blocked and not allowed from untrusted
hosts e.g the general public. Disallowing zone transfers from hosts other than
your backup DNS servers, still allow hostnames to be resolved.
DNS Zone Transfer Protocol Clarifications
http://www.ietf.org/internet-drafts/draft-ietf-dnsext-axfr-clarify-05.txt
Why is securing DNS zone transfer necessary?
http://www.sans.org/rr/paper.php?id=868
The original copy of this paper can be found at www.networkpenetration.com