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-rw-r--r--scripts/dns-check-zone.nse450
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diff --git a/scripts/dns-check-zone.nse b/scripts/dns-check-zone.nse
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+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
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