May
26
2010
Backtrack 4: Information Gathering: DNS: Fierce – locate non-contiguous IP space and hostnames against specified domains
Posted by purehate in Security at 6:39 AMThe final tool in the DNS Section is called fierce. It is a perl script written by rsnake. Fierce tries multiple techniques to find all the IP addresses and hostnames used by a target. These include – trying to dump the SOA records, do a zone transfer, searching for commonly used domain names with a dictionary attack, adjacency scan and a few more. Fierce is meant specifically to locate likely targets both inside and outside a corporate network. Only those targets are listed (unless the -nopattern switch is used). No exploitation is performed (unless you do something intentionally malicious with the -connect switch). Fierce is a reconnaissance tool. Fierce is a PERL script that quickly scans domains using several tactics.
Lets look at the help output to see what our options are:
root@666:/pentest/enumeration/fierce# ./fierce.pl -h
fierce.pl (C) Copywrite 2006-2008 - By RSnake at http://ha.ckers.org/fierce/
Usage: perl fierce.pl [-dns example.com] [OPTIONS]
Overview:
Fierce is a semi-lightweight scanner that helps locate non-contiguous
IP space and hostnames against specified domains. It's really meant
as a pre-cursor to nmap, unicornscan, nessus, nikto, etc, since all
of those require that you already know what IP space you are looking
for. This does not perform exploitation and does not scan the whole
internet indiscriminately. It is meant specifically to locate likely
targets both inside and outside a corporate network. Because it uses
DNS primarily you will often find mis-configured networks that leak
internal address space. That's especially useful in targeted malware.
Options:
-connect Attempt to make http connections to any non RFC1918
(public) addresses. This will output the return headers but
be warned, this could take a long time against a company with
many targets, depending on network/machine lag. I wouldn't
recommend doing this unless it's a small company or you have a
lot of free time on your hands (could take hours-days).
Inside the file specified the text "Host:n" will be replaced
by the host specified. Usage:
perl fierce.pl -dns example.com -connect headers.txt
-delay The number of seconds to wait between lookups.
-dns The domain you would like scanned.
-dnsfile Use DNS servers provided by a file (one per line) for
reverse lookups (brute force).
-dnsserver Use a particular DNS server for reverse lookups
(probably should be the DNS server of the target). Fierce
uses your DNS server for the initial SOA query and then uses
the target's DNS server for all additional queries by default.
-file A file you would like to output to be logged to.
-fulloutput When combined with -connect this will output everything
the webserver sends back, not just the HTTP headers.
-help This screen.
-nopattern Don't use a search pattern when looking for nearby
hosts. Instead dump everything. This is really noisy but
is useful for finding other domains that spammers might be
using. It will also give you lots of false positives,
especially on large domains.
-range Scan an internal IP range (must be combined with
-dnsserver). Note, that this does not support a pattern
and will simply output anything it finds. Usage:
perl fierce.pl -range 111.222.333.0-255 -dnsserver ns1.example.co
-search Search list. When fierce attempts to traverse up and
down ipspace it may encounter other servers within other
domains that may belong to the same company. If you supply a
comma delimited list to fierce it will report anything found.
This is especially useful if the corporate servers are named
different from the public facing website. Usage:
perl fierce.pl -dns examplecompany.com -search corpcompany,blahcompany
Note that using search could also greatly expand the number of
hosts found, as it will continue to traverse once it locates
servers that you specified in your search list. The more the
better.
-stop Stop scan if Zone Transfer works.
-suppress Suppress all TTY output (when combined with -file).
-tcptimeout Specify a different timeout (default 10 seconds). You
may want to increase this if the DNS server you are querying
is slow or has a lot of network lag.
-threads Specify how many threads to use while scanning (default
is single threaded).
-traverse Specify a number of IPs above and below whatever IP you
have found to look for nearby IPs. Default is 5 above and
below. Traverse will not move into other C blocks.
-version Output the version number.
-wide Scan the entire class C after finding any matching
hostnames in that class C. This generates a lot more traffic
but can uncover a lot more information.
-wordlist Use a seperate wordlist (one word per line). Usage:
perl fierce.pl -dns examplecompany.com -wordlist dictionary.txt
As you can see there are lots of options included in fierce.
lets try a regular query with the search flag:
(the search flag is useful if you are pretty sure of a subdomain name)
root@666:/pentest/enumeration/fierce# ./fierce.pl -dns remote-exploit.org --search mail
DNS Servers for remote-exploit.org:
ns2.icehosting.com
ns1.icehosting.com
Trying zone transfer first...
Testing ns2.icehosting.com
Whoah, it worked - misconfigured DNS server found:
remote-exploit.org. 14400 IN SOA ns1.icehosting.com. root.remote-exploit.org. (
2010030203 ; Serial
14400 ; Refresh
3600 ; Retry
1209600 ; Expire
86400 ) ; Minimum TTL
remote-exploit.org. 14400 IN MX 10 mail2.remote-exploit.org.
remote-exploit.org. 14400 IN MX 20 mail.remote-exploit.org.
remote-exploit.org. 14400 IN A 97.74.188.5
remote-exploit.org. 14400 IN NS ns1.icehosting.com.
remote-exploit.org. 14400 IN NS ns2.icehosting.com.
balkan.remote-exploit.org. 14400 IN A 208.68.234.113
beta.remote-exploit.org. 14400 IN A 78.159.102.208
de.remote-exploit.org. 14400 IN A 208.68.234.113
es.remote-exploit.org. 14400 IN A 208.68.234.113
foo.remote-exploit.org. 14400 IN A 208.68.234.113
forum.remote-exploit.org. 14400 IN CNAME forums.remote-exploit.org.
forums.remote-exploit.org. 14400 IN A 208.68.234.113
fr.remote-exploit.org. 14400 IN A 208.68.234.113
ftp.remote-exploit.org. 14400 IN A 78.159.102.208
it.remote-exploit.org. 14400 IN A 208.68.234.113
localhost.remote-exploit.org. 14400 IN A 127.0.0.1
mail.remote-exploit.org. 14400 IN A 147.87.98.225
mail2.remote-exploit.org. 14400 IN A 147.87.98.225
new.remote-exploit.org. 14400 IN A 78.159.102.208
oldwiki.remote-exploit.org. 14400 IN A 78.159.102.208
pop.remote-exploit.org. 14400 IN A 78.159.102.208
smtp.remote-exploit.org. 14400 IN A 78.159.102.208
www.remote-exploit.org. 14400 IN A 97.74.188.5
Okay, trying the good old fashioned way... brute force
Checking for wildcard DNS...
Nope. Good.
Now performing 1896 test(s)...
78.159.102.208 beta.remote-exploit.org
208.68.234.113 de.remote-exploit.org
208.68.234.113 es.remote-exploit.org
forum.remote-exploit.org alias forums.remote-exploit.org
forums.remote-exploit.org address 208.68.234.113
208.68.234.113 forum.remote-exploit.org
208.68.234.113 forums.remote-exploit.org
208.68.234.113 fr.remote-exploit.org
78.159.102.208 ftp.remote-exploit.org
208.68.234.113 it.remote-exploit.org
127.0.0.1 localhost.remote-exploit.org
147.87.98.225 mail.remote-exploit.org
147.87.98.225 mail2.remote-exploit.org
78.159.102.208 new.remote-exploit.org
78.159.102.208 pop.remote-exploit.org
78.159.102.208 smtp.remote-exploit.org
97.74.188.5 www.remote-exploit.org
Subnets found (may want to probe here using nmap or unicornscan):
127.0.0.0-255 : 1 hostnames found.
147.87.98.0-255 : 2 hostnames found.
208.68.234.0-255 : 6 hostnames found.
78.159.102.0-255 : 5 hostnames found.
97.74.188.0-255 : 1 hostnames found.
Done with Fierce scan: http://ha.ckers.org/fierce/
Found 16 entries.
Have a nice day.
This is a perfect example of a successful fierce session. We got a zone transfer and found a mis-configured nameserver. We also got a list of subdomains which we can compare against some of our other tools and we also got some subnets which we can do further checks on.
Fierce has many other options you can explore which can narrow down your results to only the relevant ones.
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I’ve Found a great DNS scanner that can locate any DNS server at your network (multi-subnet) it can also test if the DNS is answering anyones requests or not. The tool is called DNS Locator.
[Reply]
alex Reply:
September 10th, 2010 at 11:40 PM
Hello sysAdmin,
We removed the link from the comment above since the tool you recommended costs money we consider this to be an ad. I did include the name though so if people are interested in paying $40 for such a tool they can search for it.
Thanks.
alex
[Reply]