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mirror of https://github.com/nmap/nmap.git synced 2025-12-09 22:21:29 +00:00

Merge r22369:22777 from /nmap-exp/david/nmap-nsec. This adds the

dns-nsec-enum script, originally by John Bond and improved by him and
me.

Changes in dns.lua:
  Add dnssec option to dns.query that adds an OPT RR with the DO (DNSSEC
    okay) flag set.
  Add answer fetcher for NSEC records (unused currently).
  Add decoder for NSEC records.
  Add rudimentary handling of the additional section in dns.encode.
  Add a check that a decoder exists before trying to call it.
 
Also added a copy of the simplified BSD license that the new script is
under.
This commit is contained in:
david
2011-03-27 04:24:43 +00:00
parent e1e50c819d
commit 477bd66fc9
5 changed files with 524 additions and 7 deletions

View File

@@ -38,6 +38,9 @@ On Windows only, Nmap uses:
distributed with Nmap in the subdirectory mswin32/winpcap.
http://www.winpcap.org/
Certain Nmap Scripting Engine scripts use the simplified BSD license in
licenses/BSD-simplified.
Zenmap and Ndiff require:
o Python. The binary distributions of Nmap include a Python interpreter
and various libraries, built using either py2exe or py2app.

View File

@@ -0,0 +1,26 @@
Copyright. All rights reserved.
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
The views and conclusions contained in the software and documentation are those
of the authors and should not be interpreted as representing official policies,
either expressed or implied, of the authors.

View File

@@ -43,7 +43,6 @@ get_servers = nmap.get_dns_servers
-- @class table
types = {
A = 1,
AAAA = 28,
NS = 2,
SOA = 6,
CNAME = 5,
@@ -51,8 +50,11 @@ types = {
HINFO = 13,
MX = 15,
TXT = 16,
AAAA = 28,
SRV = 33,
OPT = 41,
SSHFP = 44,
NSEC = 47,
AXFR = 252,
ANY = 255
}
@@ -277,6 +279,10 @@ function query(dname, options)
addQuestion(pkt, dname, dtype)
if options.norecurse then pkt.flags.RD = false end
if options.dnssec then
addOPT(pkt, {DO = true})
end
local data = encode(pkt)
local status, response = sendPackets(data, host, port, options.timeout, options.sendCount, options.multiple)
@@ -484,6 +490,29 @@ answerFetcher[types.SRV] = function(dec, retAll)
return true, answers
end
-- Answer fetcher for NSEC records.
-- @param dec Decoded DNS response.
-- @param retAll If true, return all entries, not just the first.
-- @return True if one or more answers of the required type were found - otherwise false.
-- @return String first dns NSEC record or Table of NSEC records or String Error message.
-- Note that the format of a returned NSEC answer is "name:dname:types".
answerFetcher[types.NSEC] = function(dec, retAll)
local nsec, answers = {}, {}
for _, auth in ipairs(dec.auth) do
if auth.NSEC then nsec[#nsec+1] = auth.NSEC end
if not retAll then break end
end
if #nsec == 0 then
stdnse.print_debug(1, "dns.answerFetcher found no records of the required type: NSEC")
return false, "No Answers"
end
for _, nsecrec in ipairs(nsec) do
table.insert( answers, ("%s:%s:%s"):format(nsecrec.name or "-", nsecrec.dname or "-", stdnse.strjoin(":", nsecrec.types) or "-"))
end
if not retAll then return true, answers[1] end
return true, answers
end
-- Answer fetcher for NS records.
-- @name answerFetcher[types.NS]
-- @class function
@@ -537,8 +566,7 @@ function findNiceAnswer(dtype, dec, retAll)
if answerFetcher[dtype] then
return answerFetcher[dtype](dec, retAll)
else
stdnse.print_debug(1, "dns.findNiceAnswer() does not have an answerFetcher for dtype %s",
(type(dtype) == 'string' and dtype) or type(dtype) or "nil")
stdnse.print_debug(1, "dns.findNiceAnswer() does not have an answerFetcher for dtype %s", tostring(dtype))
return false, "Unable to handle response"
end
elseif (dec.flags.RC3 and dec.flags.RC4) then
@@ -729,6 +757,21 @@ local function encodeUpdates(updates)
return encQ
end
---
-- Encodes the additional part of a DNS request.
-- @param additional Table of additional records. Each must have the keys
-- <code>type</code>, <code>class</code>, <code>ttl</code>, <code>rdlen</code>,
-- and <code>rdata</code>.
-- @return Encoded additional string.
local function encodeAdditional(additional)
if type(additional) ~= "table" then return nil end
local encA = ""
for _, v in ipairs(additional) do
encA = encA .. bin.pack(">xSSISA", v.type, v.class, v.ttl, v.rdlen, v.rdata)
end
return encA
end
---
-- Encodes DNS flags to a binary digit string.
-- @param flags Flag table, each entry representing a flag (QR, OCx, AA, TC, RD,
@@ -758,14 +801,15 @@ end
---
-- Encode a DNS packet.
--
-- Caution: doesn't encode answer, authority and additional part.
-- Caution: doesn't encode answer and authority part.
-- @param pkt Table representing DNS packet, initialized by
-- <code>newPacket</code>.
-- @return Encoded DNS packet.
function encode(pkt)
if type(pkt) ~= "table" then return nil end
local encFlags = encodeFlags(pkt.flags)
local data = encodeQuestions(pkt.questions)
local questions = encodeQuestions(pkt.questions)
local additional = encodeAdditional(pkt.additional)
local qorzlen = #pkt.questions
local aorplen = #pkt.answers
local aorulen = #pkt.auth
@@ -779,7 +823,7 @@ function encode(pkt)
data = data .. encodeUpdates( pkt.updates )
end
local encStr = bin.pack(">SBS4", pkt.id, encFlags, qorzlen, aorplen, aorulen, #pkt.additional) .. data
local encStr = bin.pack(">SBS4", pkt.id, encFlags, qorzlen, aorplen, aorulen, #pkt.additional) .. questions .. additional
return encStr
end
@@ -911,6 +955,32 @@ decoder[types.SOA] = function(entry, data, pos)
= bin.unpack(">I5", data, np)
end
-- Decodes NSEC records, puts result in <code>entry.NSEC</code>.
--
-- <code>entry.NSEC</code> has the fields <code>dname</code>,
-- <code>NSEC</code>, <code>name</code>, <code>WinBlockNo</code>,
-- <code>bmplength</code>, <code>bin</code>, and <code>types</code>.
-- @param entry RR in packet.
-- @param data Complete encoded DNS packet.
-- @param pos Position in packet after RR.
decoder[types.NSEC] = function (entry, data, pos)
local np = pos - #entry.data
entry.NSEC = {}
entry.NSEC.dname = entry.dname
entry.NSEC.NSEC = true
np, entry.NSEC.name = decStr(data, np)
np, entry.NSEC.WinBlockNo, entry.NSEC.bmplength = bin.unpack(">CC", data, np)
np, entry.NSEC.bin = bin.unpack("B".. entry.NSEC.bmplength, data, np)
entry.NSEC.types = {}
for i=1, string.len(entry.NSEC.bin) do
local bit = string.sub(entry.NSEC.bin,i,i)
if bit == "1" then
--the first bit represents window block 0 hence -1
table.insert(entry.NSEC.types, (entry.NSEC.WinBlockNo*256+i-1))
end
end
end
-- Decodes records that consist only of one domain, for example CNAME, NS, PTR.
-- Puts result in <code>entry.domain</code>.
-- @param entry RR in packet.
@@ -1030,7 +1100,9 @@ local function decodeRR(data, count, pos)
pos, currRR.data = bin.unpack("A" .. reslen, data, pos)
-- try to be smart: decode per type
decoder[currRR.dtype](currRR, data, pos)
if decoder[currRR.dtype] then
decoder[currRR.dtype](currRR, data, pos)
end
table.insert(ans, currRR)
end
@@ -1153,6 +1225,42 @@ function addZone(pkt, dname)
return pkt
end
---
-- Encodes the Z bitfield of an OPT record.
-- @param flags Flag table, each entry representing a flag (only DO flag implmented).
-- @return Binary digit string representing flags.
local function encodeOPT_Z(flags)
if type(flags) == "string" then return flags end
if type(flags) ~= "table" then return nil end
local bits = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
for n, k in pairs({[1] = "DO"}) do
if flags[k] then
bits[n] = 1
end
end
return table.concat(bits)
end
---
-- Adds an OPT RR to a DNS packet's additional section. Only the table of Z
-- flags is supported (i.e., not RDATA). See RFC 2671 section 4.3.
-- @param pkt Table representing DNS packet.
-- @param Z Table of Z flags. Only DO is supported.
function addOPT(pkt, Z)
if type(pkt) ~= "table" then return nil end
if type(pkt.additional) ~= "table" then return nil end
local _, Z_int = bin.unpack(">S", bin.pack("B", encodeOPT_Z(Z)))
local opt = {
type = types.OPT,
class = 4096, -- Actually the sender UDP payload size.
ttl = 0 * (0x01000000) + 0 * (0x00010000) + Z_int,
rdlen = 0,
rdata = "",
}
table.insert(pkt.additional, opt)
return pkt
end
---
-- Adds a update to a DNS packet table
-- @param pkt Table representing DNS packet.

379
scripts/dns-nsec-enum.nse Normal file
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@@ -0,0 +1,379 @@
description = [[
Enumerates DNS names using the DNSSEC NSEC-walking technique.
Output is arranged by domain. Within a domain, subzones are shown with
increased indentation.
The NSEC response record in DNSSEC is used to give negative answers to
queries, but it has the side effect of allowing enumeration of all
names, much like a zone transfer. This script doesn't work against
servers that use NSEC3 rather than NSEC.
]]
---
-- @args dns-nsec-enum.domains The domain or list of domains to
-- enumerate. If not provided, the script will make a guess based on the
-- name of the target.
--
-- @usage
-- nmap -sSU -p 53 --script dns-nsec-enum --script-args dns-nsec-enum.domains=example.com <target>
--
-- @output
-- 53/udp open domain udp-response
-- | dns-nsec-enum:
-- | example.com
-- | bulbasaur.example.com
-- | charmander.example.com
-- | dugtrio.example.com
-- | www.dugtrio.example.com
-- | gyarados.example.com
-- | johto.example.com
-- | blue.johto.example.com
-- | green.johto.example.com
-- | ns.johto.example.com
-- | red.johto.example.com
-- | ns.example.com
-- | snorlax.example.com
-- |_ vulpix.example.com
author = "John Bond"
license = "Simplified (2-clause) BSD license--See http://nmap.org/svn/docs/licenses/BSD-simplified"
categories = {"discovery", "intrusive"}
require "stdnse"
require "shortport"
require "dns"
portrule = shortport.port_or_service(53, "domain", {"tcp", "udp"})
local function remove_empty(t)
local result = {}
for _, v in ipairs(t) do
if v ~= "" then
result[#result + 1] = v
end
end
return result
end
local function split(domain)
return stdnse.strsplit("%.", domain)
end
local function join(components)
return stdnse.strjoin(".", remove_empty(components))
end
-- Remove the first component of a domain name. Return nil if the number of
-- components drops below min_length (default 0).
local function remove_component(domain, min_length)
local components
min_length = min_length or 0
components = split(domain)
if #components <= min_length then
return nil
end
table.remove(components, 1)
return join(components)
end
-- Guess the domain given a host. Return nil on failure. This function removes
-- a domain name component unless the name would become shorter than 2
-- components.
local function guess_domain(host)
local name
local components
name = stdnse.get_hostname(host)
if name and name ~= host.ip then
return remove_component(name, 2) or name
else
return nil
end
end
local function invert(t)
local result = {}
for k, v in pairs(t) do
result[v] = k
end
return result
end
-- RFC 952: "A 'name' is a text string up to 24 characters drawn from the
-- alphabet (A-Z), digits (0-9), minus sign (-), and period (.). ... The first
-- character must be an alpha character."
-- RFC 1123, section 2.1: "One aspect of host name syntax is hereby changed:
-- the restriction on the first character is relaxed to allow either a letter
-- or a digit."
-- RFC 2782: An underscore (_) is prepended to the service identifier to avoid
-- collisions with DNS labels that occur in nature.
local DNS_CHARS = { string.byte("-0123456789_abcdefghijklmnopqrstuvwxyz", 1, -1) }
local DNS_CHARS_INV = invert(DNS_CHARS)
-- Return the lexicographically next component, or nil if component is the
-- lexicographically last.
local function increment_component(name)
local i, bytes, indexes
-- Easy cases first.
if #name == 0 then
return "0"
elseif #name < 63 then
return name .. "-"
elseif #name > 64 then
-- Shouldn't happen.
return nil
end
-- Convert the string into an array of indexes into DNS_CHARS.
indexes = {}
for i, b in ipairs({ string.byte(name, 1, -1) }) do
indexes[i] = DNS_CHARS_INV[b]
end
-- Increment.
i = #name
while i >= 1 do
repeat
indexes[i] = indexes[i] + 1
-- No "-" in first position.
until not (i == 1 and string.char(DNS_CHARS[indexes[i]]) == "-")
if indexes[i] > #DNS_CHARS then
-- Wrap around, next digit.
indexes[i] = 1
else
break
end
i = i - 1
end
-- Overflow.
if i == 0 then
return nil
end
-- Convert array of indexes back into string.
bytes = {}
for i, index in ipairs(indexes) do
bytes[i] = DNS_CHARS[index]
end
return string.char(unpack(bytes))
end
-- Return the lexicographically next domain name that does not add a new
-- subdomain. This is used after enumerating a whole subzone to jump out of the
-- subzone and on to more names.
local function bump_domain(domain)
local components
components = split(domain)
while #components > 0 do
components[1] = increment_component(components[1])
if components[1] then
break
else
table.remove(components[1])
end
end
if #components == 0 then
return nil
else
return join(components)
end
end
-- Return the lexicographically next domain name. This adds a new subdomain
-- consisting of the smallest character. This function never returns a domain
-- outside the current subzone.
local function next_domain(domain)
if #domain == 0 then
return "0"
else
return "0" .. "." .. domain
end
end
-- Cut out a portion of an array and return it as a new array, setting the
-- elements in the original array to nil.
local function excise(t, i, j)
local result
result = {}
if j < 0 then
j = #t + j + 1
end
for i = i, j do
result[#result + 1] = t[i]
t[i] = nil
end
return result
end
-- Remove a suffix from a domain (to isolate a subdomain from its parent).
local function remove_suffix(domain, suffix)
local dc, sc
dc = split(domain)
sc = split(suffix)
while #dc > 0 and #sc > 0 and dc[#dc] == sc[#sc] do
dc[#dc] = nil
sc[#sc] = nil
end
return join(dc), join(sc)
end
-- Return the subset of authoritative records with the given label.
local function auth_filter(retPkt, label)
local result = {}
for _, rec in ipairs(retPkt.auth) do
if rec[label] then
result[#result + 1] = rec[label]
end
end
return result
end
-- "Less than" function for two domain names. Compares starting with the last
-- component.
local function domain_lt(a, b)
local a_parts, b_parts
a_parts = split(a)
b_parts = split(b)
while #a_parts > 0 and #b_parts > 0 do
if a_parts[#a_parts] < b_parts[#b_parts] then
return true
elseif a_parts[#a_parts] > b_parts[#b_parts] then
return false
end
a_parts[#a_parts] = nil
b_parts[#b_parts] = nil
end
return #a_parts < #b_parts
end
-- Find the NSEC record that brackets the given domain.
local function get_next_nsec(retPkt, domain)
for _, nsec in ipairs(auth_filter(retPkt, "NSEC")) do
-- The last NSEC record points backwards to the start of the subzone.
if domain_lt(nsec.dname, domain) and not domain_lt(nsec.dname, nsec.name) then
return nsec
end
if domain_lt(nsec.dname, domain) and domain_lt(domain, nsec.name) then
return nsec
end
end
end
local function empty(t)
return not next(t)
end
-- Enumerate a single domain.
local function enum(host, port, domain)
local all_results = {}
local seen = {}
local subdomain = next_domain("")
while subdomain do
local result = {}
local status, result, nsec
stdnse.print_debug("Trying %q.%q", subdomain, domain)
status, result = dns.query(join({subdomain, domain}), {host = host.ip, dtype='A', retAll=true, retPkt=true, dnssec=true})
nsec = status and get_next_nsec(result, join({subdomain, domain})) or nil
if nsec then
local first, last, remainder
local index
first, remainder = remove_suffix(nsec.dname, domain)
if #remainder > 0 then
stdnse.print_debug("Result name %q doesn't end in %q.", nsec.dname, domain)
subdomain = nil
break
end
last, remainder = remove_suffix(nsec.name, domain)
if #remainder > 0 then
stdnse.print_debug("Result name %q doesn't end in %q.", nsec.name, domain)
subdomain = nil
break
end
if #last == 0 then
stdnse.print_debug("Wrapped")
subdomain = nil
break
end
if not seen[first] then
table.insert(all_results, join({first, domain}))
seen[first] = #all_results
end
index = seen[last]
if index then
-- Ignore if first is the original domain.
if #first > 0 then
subdomain = bump_domain(last)
-- Replace a chunk of the output with a sub-table for the zone.
all_results[index] = excise(all_results, index, -1)
end
else
stdnse.print_debug("adding %s", last)
subdomain = next_domain(last)
table.insert(all_results, join({last, domain}))
seen[last] = #all_results
end
else
local parent = remove_component(subdomain, 1)
-- This branch is entered if name resolution failed or
-- there were no NSEC records. If at the top, quit.
-- Otherwise continue to the next subdomain.
if parent then
subdomain = bump_domain(parent)
else
return nil
end
end
end
return all_results
end
action = function(host, port)
local output = {}
local domains
domains = stdnse.get_script_args('dns-nsec-enum.domains')
if not domains then
domains = guess_domain(host)
end
if not domains then
return string.format("Can't determine domain for host %s; use %s.domains script arg.", host.ip, SCRIPT_NAME)
end
if type(domains) == 'string' then
domains = { domains }
end
for _, domain in ipairs(domains) do
local result = enum(host, port, domain)
if type(result) == "table" then
result["name"] = domain
output[#output + 1] = result
else
output[#output + 1] = "No NSEC records found"
end
end
return stdnse.format_output(true, output)
end

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@@ -26,6 +26,7 @@ Entry { filename = "dhcp-discover.nse", categories = { "default", "discovery", "
Entry { filename = "dns-brute.nse", categories = { "discovery", "intrusive", } }
Entry { filename = "dns-cache-snoop.nse", categories = { "discovery", "intrusive", } }
Entry { filename = "dns-fuzz.nse", categories = { "fuzzer", "intrusive", } }
Entry { filename = "dns-nsec-enum.nse", categories = { "discovery", "intrusive", } }
Entry { filename = "dns-random-srcport.nse", categories = { "external", "intrusive", } }
Entry { filename = "dns-random-txid.nse", categories = { "external", "intrusive", } }
Entry { filename = "dns-recursion.nse", categories = { "default", "intrusive", } }