1 files changed, 450 insertions, 0 deletions
diff --git a/scripts/dns-check-zone.nse b/scripts/dns-check-zone.nse
new file mode 100644
index 0000000..043caca
--- /dev/null
+++ b/scripts/dns-check-zone.nse
@@ -0,0 +1,450 @@
+local dns = require "dns"
+local stdnse = require "stdnse"
+local table = require "table"
+local ipOps = require "ipOps"
+
+description = [[
+Checks DNS zone configuration against best practices, including RFC 1912.
+The configuration checks are divided into categories which each have a number
+of different tests.
+]]
+
+---
+-- @usage
+-- nmap -sn -Pn ns1.example.com --script dns-check-zone --script-args='dns-check-zone.domain=example.com'
+--
+-- @output
+-- | dns-check-zone:
+-- | DNS check results for domain: example.com
+-- |   SOA
+-- |     PASS - SOA REFRESH
+-- |       SOA REFRESH was within recommended range (7200s)
+-- |     PASS - SOA RETRY
+-- |       SOA RETRY was within recommended range (3600s)
+-- |     PASS - SOA EXPIRE
+-- |       SOA EXPIRE was within recommended range (1209600s)
+-- |     FAIL - SOA MNAME entry check
+-- |       SOA MNAME record is NOT listed as DNS server
+-- |     PASS - Zone serial numbers
+-- |       Zone serials match
+-- |   MX
+-- |     ERROR - Reverse MX A records
+-- |       Failed to retrieve list of mail servers
+-- |   NS
+-- |     PASS - Recursive queries
+-- |       None of the servers allow recursive queries.
+-- |     PASS - Multiple name servers
+-- |       Server has 2 name servers
+-- |     PASS - DNS name server IPs are public
+-- |       All DNS IPs were public
+-- |     PASS - DNS server response
+-- |       All servers respond to DNS queries
+-- |     PASS - Missing nameservers reported by parent
+-- |       All DNS servers match
+-- |     PASS - Missing nameservers reported by your nameservers
+-- |_      All DNS servers match
+--
+-- @args dns-check-zone.domain the dns zone to check
+--
+
+author = "Patrik Karlsson"
+license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
+categories = {"discovery", "safe", "external"}
+
+local arg_domain = stdnse.get_script_args(SCRIPT_NAME .. '.domain')
+
+
+hostrule = function(host) return ( arg_domain ~= nil ) end
+
+local PROBE_HOST = "scanme.nmap.org"
+
+local Status = {
+  PASS = "PASS",
+  FAIL = "FAIL",
+}
+
+local function isValidSOA(res)
+  if ( not(res) or type(res.answers) ~= "table" or type(res.answers[1].SOA) ~= "table" ) then
+    return false
+  end
+  return true
+end
+
+local dns_checks = {
+
+  ["NS"] = {
+    {
+      desc = "Recursive queries",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+        local result = {}
+
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+        for _, srv in ipairs(res or {}) do
+          local status, res = dns.query(PROBE_HOST, { host = srv, dtype='A' })
+          if ( status ) then
+            table.insert(result, res)
+          end
+        end
+
+        local output = "None of the servers allow recursive queries."
+        if ( 0 < #result ) then
+          output = ("The following servers allow recursive queries: %s"):format(table.concat(result, ", "))
+          return true, { status = Status.FAIL, output = output }
+        end
+        return true, { status = Status.PASS, output = output }
+      end
+    },
+
+    {
+      desc = "Multiple name servers",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+
+        local status = Status.FAIL
+        if ( 1 < #res ) then
+          status = Status.PASS
+        end
+        return true, { status = status, output = ("Server has %d name servers"):format(#res) }
+      end
+    },
+
+    {
+      desc = "DNS name server IPs are public",
+      func = function(domain, server)
+
+        local status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+
+        local result = {}
+        for _, srv in ipairs(res or {}) do
+          local status, res = dns.query(srv, { dtype='A', retAll = true })
+          if ( not(status) ) then
+            return false, ("Failed to retrieve IP for DNS: %s"):format(srv)
+          end
+          for _, ip in ipairs(res) do
+            if ( ipOps.isPrivate(ip) ) then
+              table.insert(result, ip)
+            end
+          end
+        end
+
+        local output = "All DNS IPs were public"
+        if ( 0 < #result ) then
+          output = ("The following private IPs were detected: %s"):format(table.concat(result, ", "))
+          status = Status.FAIL
+        else
+          status = Status.PASS
+        end
+
+        return true, { status = status, output = output }
+      end
+    },
+
+    {
+      desc = "DNS server response",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+
+        local result = {}
+        for _, srv in ipairs(res or {}) do
+          local status, res = dns.query(domain, { host = srv, dtype='SOA', retPkt = true })
+          if ( not(status) ) then
+            table.insert(result, res)
+          end
+        end
+
+        local output = "All servers respond to DNS queries"
+        if ( 0 < #result ) then
+          output = ("The following servers did not respond to DNS queries: %s"):format(table.concat(result, ", "))
+          return true, { status = Status.FAIL, output = output }
+        end
+        return true, { status = Status.PASS, output = output }
+      end
+    },
+
+    {
+      desc = "Missing nameservers reported by parent",
+      func = function(domain, server)
+        local tld = domain:match("%.(.*)$")
+        local status, res = dns.query(tld, { dtype = "NS", retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of TLD DNS servers"
+        end
+
+        local status, parent_res = dns.query(domain, { host = res, dtype = "NS", retAll = true, retPkt = true, noauth = true } )
+        if ( not(status) ) then
+          return false, "Failed to retrieve a list of parent DNS servers"
+        end
+
+        if ( not(status) or not(parent_res) or type(parent_res.auth) ~= "table"  ) then
+          return false, "Failed to retrieve a list of parent DNS servers"
+        end
+
+        local parent_dns = {}
+        for _, auth in ipairs(parent_res.auth) do
+          parent_dns[auth.domain] = true
+        end
+
+        status, res = dns.query(domain, { host = server, dtype = "NS", retAll = true } )
+        if ( not(status) ) then
+          return false, "Failed to retrieve a list of DNS servers"
+        end
+
+        local domain_dns = {}
+        for _,srv in ipairs(res) do domain_dns[srv] = true end
+
+        local result = {}
+        for srv in pairs(domain_dns) do
+          if ( not(parent_dns[srv]) ) then
+            table.insert(result, srv)
+          end
+        end
+
+        if ( 0 < #result ) then
+          local output = ("The following servers were found in the zone, but not in the parent: %s"):format(table.concat(result, ", "))
+          return true, { status = Status.FAIL, output = output }
+        end
+
+        return true, { status = Status.PASS, output = "All DNS servers match" }
+      end,
+    },
+
+
+    {
+      desc = "Missing nameservers reported by your nameservers",
+      func = function(domain, server)
+        local tld = domain:match("%.(.*)$")
+        local status, res = dns.query(tld, { dtype = "NS", retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of TLD DNS servers"
+        end
+
+        local status, parent_res = dns.query(domain, { host = res, dtype = "NS", retAll = true, retPkt = true, noauth = true } )
+        if ( not(status) ) then
+          return false, "Failed to retrieve a list of parent DNS servers"
+        end
+
+        if ( not(status) or not(parent_res) or type(parent_res.auth) ~= "table"  ) then
+          return false, "Failed to retrieve a list of parent DNS servers"
+        end
+
+        local parent_dns = {}
+        for _, auth in ipairs(parent_res.auth) do
+          parent_dns[auth.domain] = true
+        end
+
+        status, res = dns.query(domain, { host = server, dtype = "NS", retAll = true } )
+        if ( not(status) ) then
+          return false, "Failed to retrieve a list of DNS servers"
+        end
+
+        local domain_dns = {}
+        for _,srv in ipairs(res) do  domain_dns[srv] = true end
+
+        local result = {}
+        for srv in pairs(parent_dns) do
+          if ( not(domain_dns[srv]) ) then
+            table.insert(result, srv)
+          end
+        end
+
+        if ( 0 < #result ) then
+          local output = ("The following servers were found in the parent, but not in the zone: %s"):format(table.concat(result, ", "))
+          return true, { status = Status.FAIL, output = output }
+        end
+
+        return true, { status = Status.PASS, output = "All DNS servers match" }
+      end,
+    },
+
+  },
+
+  ["SOA"] =
+  {
+    {
+      desc = "SOA REFRESH",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='SOA', retPkt=true })
+        if ( not(status) or not(isValidSOA(res)) ) then
+          return false, "Failed to retrieve SOA record"
+        end
+
+        local refresh = tonumber(res.answers[1].SOA.refresh)
+        if ( not(refresh) ) then
+          return false, "Failed to retrieve SOA REFRESH"
+        end
+
+        if ( refresh < 1200 or refresh > 43200 ) then
+          return true, { status = Status.FAIL, output = ("SOA REFRESH was NOT within recommended range (%ss)"):format(refresh) }
+        else
+          return true, { status = Status.PASS, output = ("SOA REFRESH was within recommended range (%ss)"):format(refresh) }
+        end
+      end
+    },
+
+    {
+      desc = "SOA RETRY",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='SOA', retPkt=true })
+        if ( not(status) or not(isValidSOA(res)) ) then
+          return false, "Failed to retrieve SOA record"
+        end
+
+        local retry = tonumber(res.answers[1].SOA.retry)
+        if ( not(retry) ) then
+          return false, "Failed to retrieve SOA RETRY"
+        end
+
+        if ( retry < 180 ) then
+          return true, { status = Status.FAIL, output = ("SOA RETRY was NOT within recommended range (%ss)"):format(retry) }
+        else
+          return true, { status = Status.PASS, output = ("SOA RETRY was within recommended range (%ss)"):format(retry) }
+        end
+      end
+    },
+
+    {
+      desc = "SOA EXPIRE",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='SOA', retPkt=true })
+        if ( not(status) or not(isValidSOA(res)) ) then
+          return false, "Failed to retrieve SOA record"
+        end
+
+        local expire = tonumber(res.answers[1].SOA.expire)
+        if ( not(expire) ) then
+          return false, "Failed to retrieve SOA EXPIRE"
+        end
+
+        if ( expire < 1209600 or expire > 2419200 ) then
+          return true, { status = Status.FAIL, output = ("SOA EXPIRE was NOT within recommended range (%ss)"):format(expire) }
+        else
+          return true, { status = Status.PASS, output = ("SOA EXPIRE was within recommended range (%ss)"):format(expire) }
+        end
+      end
+    },
+
+    {
+      desc = "SOA MNAME entry check",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='SOA', retPkt=true })
+        if ( not(status) or not(isValidSOA(res)) ) then
+          return false, "Failed to retrieve SOA record"
+        end
+        local mname = res.answers[1].SOA.mname
+
+        status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+
+        for _, srv in ipairs(res or {}) do
+          if ( srv == mname ) then
+            return true, { status = Status.PASS, output = "SOA MNAME record is listed as DNS server" }
+          end
+        end
+        return true, { status = Status.FAIL, output = "SOA MNAME record is NOT listed as DNS server" }
+      end
+    },
+
+    {
+      desc = "Zone serial numbers",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='NS', retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of DNS servers"
+        end
+
+        local result = {}
+        local serial
+
+        for _, srv in ipairs(res or {}) do
+          local status, res = dns.query(domain, { host = srv, dtype='SOA', retPkt = true })
+          if ( not(status) or not(isValidSOA(res)) ) then
+            return false, "Failed to retrieve SOA record"
+          end
+
+          local s = res.answers[1].SOA.serial
+          if ( not(serial) ) then
+            serial = s
+          elseif( serial ~= s ) then
+            return true, { status = Status.FAIL, output = "Different zone serials were detected" }
+          end
+        end
+
+        return true, { status = Status.PASS, output = "Zone serials match" }
+      end,
+    },
+  },
+
+  ["MX"] = {
+
+    {
+      desc = "Reverse MX A records",
+      func = function(domain, server)
+        local status, res = dns.query(domain, { host = server, dtype='MX', retAll = true })
+        if ( not(status) ) then
+          return false, "Failed to retrieve list of mail servers"
+        end
+
+        local result = {}
+        for _, record in ipairs(res or {}) do
+          local prio, mx = record:match("^(%d*):([^:]*)")
+          local ips
+          status, ips = dns.query(mx, { dtype='A', retAll=true })
+          if ( not(status) ) then
+            return false, "Failed to retrieve A records for MX"
+          end
+
+          for _, ip in ipairs(ips) do
+            local status, res = dns.query(dns.reverse(ip), { dtype='PTR' })
+            if ( not(status) ) then
+              table.insert(result, ip)
+            end
+          end
+        end
+
+        local output = "All MX records have PTR records"
+        if ( 0 < #result ) then
+          output = ("The following IPs do not have PTR records: %s"):format(table.concat(result, ", "))
+          return true, { status = Status.FAIL, output = output }
+        end
+        return true, { status = Status.PASS, output = output }
+      end
+    },
+
+  }
+}
+
+action = function(host, port)
+  local server = host.ip
+  local output = { name = ("DNS check results for domain: %s"):format(arg_domain) }
+
+  for group in pairs(dns_checks) do
+    local group_output = { name = group }
+    for _, check in ipairs(dns_checks[group]) do
+      local status, res = check.func(arg_domain, server)
+      if ( status ) then
+        local test_res = ("%s - %s"):format(res.status, check.desc)
+        table.insert(group_output, { name = test_res, res.output })
+      else
+        local test_res = ("ERROR - %s"):format(check.desc)
+        table.insert(group_output, { name = test_res, res })
+      end
+    end
+    table.insert(output, group_output)
+  end
+  return stdnse.format_output(true, output)
+end