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