description = [[
Requests a zone transfer (AXFR) from a DNS server.
The script sends an AXFR query to a DNS server. The domain to query is
determined by examining the name given on the command line, the DNS
server's hostname, or it can be specified with the
<code>dns-zone-transfer.domain</code> script argument. If the query is
successful all domains and domain types are returned along with common
type specific data (SOA/MX/NS/PTR/A).
This script can run at different phases of an Nmap scan:
* Script Pre-scanning: in this phase the script will run before any
Nmap scan and use the defined DNS server in the arguments. The script
arguments in this phase are: <code>dns-zone-transfer.server</code> the
DNS server to use, can be a hostname or an IP address and must be
specified. The <code>dns-zone-transfer.port</code> argument is optional
and can be used to specify the DNS server port.
* Script scanning: in this phase the script will run after the other
Nmap phases and against an Nmap discovered DNS server. If we don't
have the "true" hostname for the DNS server we cannot determine a
likely zone to perform the transfer on.
Useful resources
* DNS for rocket scientists: http://www.zytrax.com/books/dns/
* How the AXFR protocol works: http://cr.yp.to/djbdns/axfr-notes.html
]]
---
-- @args dns-zone-transfer.domain Domain to transfer.
-- @args dns-zone-transfer.server DNS server. If set, this argument will
-- enable the script for the "Script Pre-scanning phase".
-- @args dns-zone-transfer.port DNS server port, this argument concerns
-- the "Script Pre-scanning phase" and it's optional, the default
-- value is <code>53</code>.
-- @args newtargets If specified, adds returned DNS records onto Nmap
-- scanning queue.
-- @args dns-zone-transfer.addall If specified, adds all IP addresses
-- including private ones onto Nmap scanning queue when the
-- script argument <code>newtargets</code> is given. The default
-- behavior is to skip private IPs (non-routable).
-- @output
-- 53/tcp open domain
-- | dns-zone-transfer:
-- | foo.com. SOA ns2.foo.com. piou.foo.com.
-- | foo.com. TXT
-- | foo.com. NS ns1.foo.com.
-- | foo.com. NS ns2.foo.com.
-- | foo.com. NS ns3.foo.com.
-- | foo.com. A 127.0.0.1
-- | foo.com. MX mail.foo.com.
-- | anansie.foo.com. A 127.0.0.2
-- | dhalgren.foo.com. A 127.0.0.3
-- | drupal.foo.com. CNAME
-- | goodman.foo.com. A 127.0.0.4 i
-- | goodman.foo.com. MX mail.foo.com.
-- | isaac.foo.com. A 127.0.0.5
-- | julie.foo.com. A 127.0.0.6
-- | mail.foo.com. A 127.0.0.7
-- | ns1.foo.com. A 127.0.0.7
-- | ns2.foo.com. A 127.0.0.8
-- | ns3.foo.com. A 127.0.0.9
-- | stubing.foo.com. A 127.0.0.10
-- | vicki.foo.com. A 127.0.0.11
-- | votetrust.foo.com. CNAME
-- | www.foo.com. CNAME
-- |_ foo.com. SOA ns2.foo.com. piou.foo.com.
-- @usage
-- nmap --script dns-zone-transfer.nse \
-- --script-args dns-zone-transfer.domain=<domain>
require('shortport')
require('strbuf')
require('stdnse')
require('listop')
require('bit')
require('tab')
require('dns')
require('target')
require('ipOps')
author = "Eddie Bell"
license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
categories = {'default', 'intrusive', 'discovery'}
-- DNS options
local dns_opts = {}
prerule = function()
dns_opts.domain, dns_opts.server,
dns_opts.port, dns_opts.addall = stdnse.get_script_args(
{"dns-zone-transfer.domain", "dnszonetransfer.domain"},
{"dns-zone-transfer.server", "dnszonetransfer.server"},
{"dns-zone-transfer.port", "dnszonetransfer.port"},
{"dns-zone-transfer.addall","dnszonetransfer.addall"}
)
if not dns_opts.domain then
stdnse.print_debug(3,
"Skipping '%s' %s, 'dnszonetransfer.domain' argument is missing.",
SCRIPT_NAME, SCRIPT_TYPE)
return false
end
if not dns_opts.server then
stdnse.print_debug(3,
"Skipping '%s' %s, 'dnszonetransfer.server' argument is missing.",
SCRIPT_NAME, SCRIPT_TYPE)
return false
end
return true
end
portrule = function(host, port)
if shortport.portnumber(53, 'tcp')(host, port) then
dns_opts.domain, dns_opts.addall = stdnse.get_script_args(
{"dns-zone-transfer.domain", "dnszonetransfer.domain"},
{"dns-zone-transfer.addall","dnszonetransfer.addall"}
)
if not dns_opts.domain then
if host.targetname then
dns_opts.domain = host.targetname
elseif host.name ~= "" then
dns_opts.domain = host.name
else
-- can't do anything without a hostname
stdnse.print_debug(3,
"Skipping '%s' %s, 'dnszonetransfer.domain' argument is missing.",
SCRIPT_NAME, SCRIPT_TYPE)
return false
end
end
dns_opts.server = host.ip
dns_opts.port = port.number
return true
end
return false
end
--- DNS query and response types.
--@class table
--@name typetab
local typetab = { 'A', 'NS', 'MD', 'MF', 'CNAME', 'SOA', 'MB', 'MG', 'MR',
'NULL', 'WKS', 'PTR', 'HINFO', 'MINFO', 'MX', 'TXT', 'RP', 'AFSDB', 'X25',
'ISDN', 'RT', 'NSAP', 'NSAP-PTR', 'SIG', 'KEY', 'PX', 'GPOS', 'AAAA', 'LOC',
'NXT', 'EID', 'NIMLOC', 'SRV', 'ATMA', 'NAPTR', 'KX', 'CERT', 'A6', 'DNAME',
'SINK', 'OPT', [250]='TSIG', [251]='IXFR', [252]='AXFR', [253]='MAILB',
[254]='MAILA', [255]='ANY', [256]='ZXFR'
}
--- Whitelist of TLDs. Only way to reliably determine the root of a domain
--@class table
--@name tld
local tld = {
'aero', 'asia', 'biz', 'cat', 'com', 'coop', 'info', 'jobs', 'mobi', 'museum',
'name', 'net', 'org', 'pro', 'tel', 'travel', 'gov', 'edu', 'mil', 'int',
'ac','ad','ae','af','ag','ai','al','am','an','ao','aq','ar','as','at','au','aw',
'ax','az','ba','bb','bd','be','bf','bg','bh','bi','bj','bm','bn','bo','br','bs',
'bt','bv','bw','by','bz','ca','cc','cd','cf','cg','ch','ci','ck','cl','cm','cn',
'co','cr','cu','cv','cx','cy','cz','de','dj','dk','dm','do','dz','ec','ee','eg',
'eh','er','es','et','eu','fi','fj','fk','fm','fo','fr','ga','gb','gd','ge','gf',
'gg','gh','gi','gl','gm','gn','gp','gq','gr','gs','gt','gu','gw','gy','hk','hm',
'hn','hr','ht','hu','id','ie','il','im','in','io','iq','ir','is','it','je','jm',
'jo','jp','ke','kg','kh','ki','km','kn','kp','kr','kw','ky','kz','la','lb','lc',
'li','lk','lr','ls','lt','lu','lv','ly','ma','mc','md','me','mg','mh','mk','ml',
'mm','mn','mo','mp','mq','mr','ms','mt','mu','mv','mw','mx','my','mz','na','nc',
'ne','nf','ng','ni','nl','no','np','nr','nu','nz','om','pa','pe','pf','pg','ph',
'pk','pl','pm','pn','pr','ps','pt','pw','py','qa','re','ro','rs','ru','rw','sa',
'sb','sc','sd','se','sg','sh','si','sj','sk','sl','sm','sn','so','sr','st','su',
'sv','sy','sz','tc','td','tf','tg','th','tj','tk','tl','tm','tn','to','tp','tr',
'tt','tv','tw','tz','ua','ug','uk','um','us','uy','uz','va','vc','ve','vg','vi',
'vn','vu','wf','ws','ye','yt','yu','za','zm','zw'
}
--- Convert two bytes into a 16bit number.
--@param data String of data.
--@param idx Index in the string (first of two consecutive bytes).
--@return 16 bit number represented by the two bytes.
function bto16(data, idx)
local b1 = string.byte(data, idx)
local b2 = string.byte(data, idx+1)
-- (b2 & 0xff) | ((b1 & 0xff) << 8)
return bit.bor(bit.band(b2, 255), bit.lshift(bit.band(b1, 255), 8))
end
--- Check if domain name element is a tld
--@param elm Domain name element to check.
--@return boolean
function valid_tld(elm)
for i,v in ipairs(tld) do
if elm == v then return true end
end
return false
end
--- Parse an RFC 1035 domain name.
--@param data String of data.
--@param offset Offset in the string to read the domain name.
function parse_domain(data, offset)
local offset, domain = dns.decStr(data, offset)
domain = domain or "<parse error>"
return offset, domain
end
--- Build RFC 1035 root domain name from the name of the DNS server
-- (e.g ns1.website.com.ar -> \007website\003com\002ar\000).
--@param host The host.
function build_domain(host)
local names, buf, x
local abs_name, i, tmp
buf = strbuf.new()
abs_name = {}
names = stdnse.strsplit('%.', host)
if names == nil then names = {host} end
-- try to determine root of domain name
for i, x in ipairs(listop.reverse(names)) do
table.insert(abs_name, x)
if not valid_tld(x) then break end
end
i = 1
abs_name = listop.reverse(abs_name)
-- prepend each element with its length
while i <= table.getn(abs_name) do
buf = buf .. string.char(string.len(abs_name[i])) .. abs_name[i]
i = i + 1
end
buf = buf .. '\000'
return strbuf.dump(buf)
end
--- Retrieve type specific data (rdata) from dns packets
function get_rdata(data, offset, ttype)
local field, info, i
info = strbuf.new()
info = info .. ''
if typetab[ttype] == nil then
return offset, ''
elseif typetab[ttype] == 'SOA' then
-- name server
offset, field = parse_domain(data, offset)
info = info .. field;
-- mail box
offset, field = parse_domain(data, offset)
info = info .. field;
-- ignore other values
offset = offset + 20
elseif typetab[ttype] == 'MX' then
-- mail server
offset = offset + 2
offset, field = parse_domain(data, offset)
info = info .. field
elseif typetab[ttype] == 'A' then
-- ip address
info = info ..
string.byte(data, offset) .. '.' ..
string.byte(data, offset+1) .. '.' ..
string.byte(data, offset+2) .. '.' ..
string.byte(data, offset+3)
offset = offset + 4
elseif typetab[ttype] == 'PTR' or typetab[ttype] == 'NS' or
typetab[ttype] == 'CNAME' then
-- domain/domain server name
offset, field = parse_domain(data, offset)
info = info .. field;
end
return offset, strbuf.dump(info, ' ')
end
--- Get a single answer record from the current offset
function get_answer_record(table, data, offset)
local line, rdlen, ttype
-- answer domain
offset, line = parse_domain(data, offset)
table.domain = line
-- answer record type
ttype = bto16(data, offset)
if not(typetab[ttype] == nil) then
table.ttype = typetab[ttype]
end
-- length of type specific data
rdlen = bto16(data, offset+8)
-- extra data, ignore ttl and class
offset, line = get_rdata(data, offset+10, ttype)
if(line == '') then
offset = offset + rdlen
return false, offset
else
table.rdata = line
end
return true, offset
end
-- parse and save uniq records in the results table
function parse_uniq_records(results, record)
if record.domain and not results['Node Names'][record.domain] then
local str = string.gsub(record.domain, "^%s*(.-)%s*$", "%1")
if not results['Node Names'][str] then
results['Node Names'][str] = 1
end
end
if record.ttype and record.rdata then
if not results[record.ttype] then
results[record.ttype] = {}
end
local str = string.gsub(record.rdata, "^%s*(.-)%s*$", "%1")
if not results[record.ttype][str] then
results[record.ttype][str] = 1
end
end
end
-- parse and save only valid records
function parse_records(number, data, results, offset)
while number > 0 do
local answer, st = {}
st, offset = get_answer_record(answer, data, offset)
if st then
parse_uniq_records(results, answer)
end
number = number - 1
end
return offset
end
-- parse and save all records in order to dump them to output
function parse_records_table(number, data, table, offset)
while number > 0 do
local answer, st = {}
st, offset = get_answer_record(answer, data, offset)
if st then
if answer.domain then
tab.add(table, 1, answer.domain)
end
if answer.ttype then
tab.add(table, 2, answer.ttype)
end
if answer.rdata then
tab.add(table, 3, answer.rdata)
end
tab.nextrow(table)
end
number = number - 1
end
return offset
end
-- An iterator that breaks up a concatentation of responses. In DNS over TCP,
-- each response is prefixed by a two-byte length (RFC 1035 section 4.2.2).
-- Responses returned by this iterator include the two-byte length prefix.
function responses_iter(data)
local offset = 1
return function()
local length, remaining, response
remaining = string.len(data) - offset + 1
if remaining == 0 then
return nil
end
assert(remaining >= 14 + 2)
length = bto16(data, offset)
assert(length <= remaining)
-- Skip over the length field.
offset = offset + 2
response = string.sub(data, offset, offset + length - 1)
offset = offset + length
return response
end
end
-- add axfr results to Nmap scan queue
function add_zone_info(response)
local RR = {}
for data in responses_iter(response) do
local offset, line = 1
local questions = bto16(data, offset+4)
local answers = bto16(data, offset+6)
local auth_answers = bto16(data, offset+8)
local add_answers = bto16(data, offset+10)
-- move to beginning of first section
offset = offset + 12
if questions > 1 then
return false, 'More then 1 question record, something has gone wrong'
end
if answers == 0 then
return false, 'transfer successful but no records'
end
-- skip over the question section, we don't need it
if questions == 1 then
offset, line = parse_domain(data, offset)
offset = offset + 4
end
-- parse all available resource records
stdnse.print_debug(3,
"Script %s: parsing ANCOUNT == %d, NSCOUNT == %d, ARCOUNT == %d",
SCRIPT_NAME, answers, auth_answers, add_answers)
RR['Node Names'] = {}
offset = parse_records(answers, data, RR, offset)
offset = parse_records(auth_answers, data, RR, offset)
offset = parse_records(add_answers, data, RR, offset)
end
local outtab, nhosts = tab.new(), 0
local newhosts_count, status, ret = 0, false
tab.addrow(outtab, "Domains", "Added Targets")
for rdata in pairs(RR['Node Names']) do
status, ret = target.add(rdata)
if not status then
stdnse.print_debug(3, "Error: failed to add all Node Names.")
break
end
newhosts_count = newhosts_count + ret
end
if newhosts_count == 0 then
return false, ret and ret or "Error: failed to add DNS records."
end
tab.addrow(outtab, "Node Names", newhosts_count)
nhosts = newhosts_count
tab.nextrow(outtab)
tab.addrow(outtab, "DNS Records", "Added Targets")
for rectype in pairs(RR) do
newhosts_count = 0
-- filter Private IPs
if rectype == 'A' then
for rdata in pairs(RR[rectype]) do
if dns_opts.addall or not ipOps.isPrivate(rdata) then
status, ret = target.add(rdata)
if not status then
stdnse.print_debug(3,
"Error: failed to add all 'A' records.")
break
end
newhosts_count = newhosts_count + ret
end
end
elseif rectype ~= 'Node Names' then
for rdata in pairs(RR[rectype]) do
status, ret = target.add(rdata)
if not status then
stdnse.print_debug(3,
"Error: failed to add all '%s' records.", rectype)
break
end
newhosts_count = newhosts_count + ret
end
end
if newhosts_count ~= 0 then
tab.addrow(outtab, rectype, newhosts_count)
nhosts = nhosts + newhosts_count
elseif nhosts == 0 then
-- error: we can't add new targets
return false, ret and ret or "Error: failed to add DNS records."
end
end
-- error: no *valid records* or we can't add new targets
if nhosts == 0 then
return false, "Error: failed to add valid DNS records."
end
return true, tab.dump(outtab) .. "\n" ..
string.format("Total new targets added to Nmap scan queue: %d.",
nhosts)
end
function dump_zone_info(table, response)
for data in responses_iter(response) do
local offset, line = 1
-- number of available records
local questions = bto16(data, offset+4)
local answers = bto16(data, offset+6)
local auth_answers = bto16(data, offset+8)
local add_answers = bto16(data, offset+10)
-- move to beginning of first section
offset = offset + 12
if questions > 1 then
return false, 'More then 1 question record, something has gone wrong'
end
if answers == 0 then
return false, 'transfer successful but no records'
end
-- skip over the question section, we don't need it
if questions == 1 then
offset, line = parse_domain(data, offset)
offset = offset + 4
end
-- parse all available resource records
stdnse.print_debug(3,
"Script %s: parsing ANCOUNT == %d, NSCOUNT == %d, ARCOUNT == %d",
SCRIPT_NAME, answers, auth_answers, add_answers)
offset = parse_records_table(answers, data, table, offset)
offset = parse_records_table(auth_answers, data, table, offset)
offset = parse_records_table(add_answers, data, table, offset)
end
return true
end
action = function(host, port)
if not dns_opts.domain then
return stdnse.format_output(false,
string.format("'%s' script needs a dnszonetransfer.domain argument.",
SCRIPT_TYPE))
end
if not dns_opts.port then
dns_opts.port = 53
end
local soc = nmap.new_socket()
local catch = function() soc:close() end
local try = nmap.new_try(catch)
soc:set_timeout(4000)
try(soc:connect(dns_opts.server, dns_opts.port))
local req_id = '\222\173'
local offset = 1
local name = build_domain(string.lower(dns_opts.domain))
local pkt_len = string.len(name) + 16
-- build axfr request
local buf = strbuf.new()
buf = buf .. '\000' .. string.char(pkt_len) .. req_id
buf = buf .. '\000\000\000\001\000\000\000\000\000\000'
buf = buf .. name .. '\000\252\000\001'
try(soc:send(strbuf.dump(buf)))
-- read all data returned. Common to have
-- multiple packets from a single request
local response = strbuf.new()
while true do
local status, data = soc:receive_bytes(1)
if not status then break end
response = response .. data
end
soc:close()
local response_str = strbuf.dump(response)
local length = string.len(response_str)
-- check server response code
if length < 6 or
not (bit.band(string.byte(response_str, 6), 15) == 0) then
return nil
end
-- add axfr results to Nmap scanning queue
if target.ALLOW_NEW_TARGETS then
local status, ret = add_zone_info(response_str)
if not status then
return stdnse.format_output(false, ret)
end
return stdnse.format_output(true, ret)
-- dump axfr results
else
local table = tab.new()
local status, ret = dump_zone_info(table, response_str)
if not status then
return stdnse.format_output(false, ret)
end
return '\n' .. tab.dump(table)
end
end
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