local base64 = require "base64" local ipOps = require "ipOps" local nmap = require "nmap" local shortport = require "shortport" local ssh1 = require "ssh1" local ssh2 = require "ssh2" local stdnse = require "stdnse" local table = require "table" local base64 = require "base64" local openssl = stdnse.silent_require "openssl" description = [[ Shows SSH hostkeys. Shows the target SSH server's key fingerprint and (with high enough verbosity level) the public key itself. It records the discovered host keys in nmap.registry for use by other scripts. Output can be controlled with the ssh_hostkey script argument. You may also compare the retrieved key with the keys in your known-hosts file using the known-hosts argument. The script also includes a postrule that check for duplicate hosts using the gathered keys. ]] --- --@usage -- nmap host --script ssh-hostkey --script-args ssh_hostkey=full -- nmap host --script ssh-hostkey --script-args ssh_hostkey=all -- nmap host --script ssh-hostkey --script-args ssh_hostkey='visual bubble' -- --@args ssh_hostkey Controls the output format of keys. Multiple values may be -- given, separated by spaces. Possible values are -- * "full": The entire key, not just the fingerprint. -- * "bubble": Bubble Babble output, -- * "visual": Visual ASCII art representation. -- * "all": All of the above. -- @args ssh-hostkey.known-hosts If this is set, the script will check if the -- known hosts file contains a key for the host being scanned and will compare -- it with the keys that have been found by the script. The script will try to -- detect your known-hosts file but you can, optionally, pass the path of the -- file to this option. -- -- @args ssh-hostkey.known-hosts-path. Path to a known_hosts file. --@output -- 22/tcp open ssh -- | ssh-hostkey: 2048 f0:58:ce:f4:aa:a4:59:1c:8e:dd:4d:07:44:c8:25:11 (RSA) -- 22/tcp open ssh -- | ssh-hostkey: 2048 f0:58:ce:f4:aa:a4:59:1c:8e:dd:4d:07:44:c8:25:11 (RSA) -- | +--[ RSA 2048]----+ -- | | .E*+ | -- | | oo | -- | | . o . | -- | | O . . | -- | | o S o . | -- | | = o + . | -- | | . * o . | -- | | = . | -- | | o . | -- |_ +-----------------+ -- 22/tcp open ssh syn-ack -- | ssh-hostkey: Key comparison with known_hosts file: -- | GOOD Matches in known_hosts file: -- | L7: 199.19.117.60 -- | L11: foo -- | L15: bar -- | L19: -- | WRONG Matches in known_hosts file: -- | L3: 199.19.117.60 -- | ssh-hostkey: 2048 xuvah-degyp-nabus-zegah-hebur-nopig-bubig-difeg-hisym-rumef-cuxex (RSA) -- |_ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwVuv2gcr0maaKQ69VVIEv2ob4OxnuI64fkeOnCXD1lUx5tTA+vefXUWEMxgMuA7iX4irJHy2zer0NQ3Z3yJvr5scPgTYIaEOp5Uo/eGFG9Agpk5wE8CoF0e47iCAPHqzlmP2V7aNURLMODb3jVZuI07A2ZRrMGrD8d888E2ORVORv1rYeTYCqcMMoVFmX9l3gWEdk4yx3w5sD8v501Iuyd1v19mPfyhrI5E1E1nl/Xjp5N0/xP2GUBrdkDMxKaxqTPMie/f0dXBUPQQN697a5q+5lBRPhKYOtn6yQKCd9s1Q22nxn72Jmi1RzbMyYJ52FosDT755Qmb46GLrDMaZMQ== -- --@output -- Post-scan script results: -- | ssh-hostkey: Possible duplicate hosts -- | Key 1024 60:ac:4d:51:b1:cd:85:09:12:16:92:76:1d:5d:27:6e (DSA) used by: -- | 192.168.1.1 -- | 192.168.1.2 -- | Key 2048 2c:22:75:60:4b:c3:3b:18:a2:97:2c:96:7e:28:dc:dd (RSA) used by: -- | 192.168.1.1 -- |_ 192.168.1.2 -- --@xmloutput -- -- ssh-dss 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 -- 1024 -- 18782fd3be7178a38e584b5a83bd60a8 -- ssh-dss --
-- -- ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwVuv2gcr0maaKQ69VVIEv2ob4OxnuI64fkeOnCXD1lUx5tTA+vefXUWEMxgMuA7iX4irJHy2zer0NQ3Z3yJvr5scPgTYIaEOp5Uo/eGFG9Agpk5wE8CoF0e47iCAPHqzlmP2V7aNURLMODb3jVZuI07A2ZRrMGrD8d888E2ORVORv1rYeTYCqcMMoVFmX9l3gWEdk4yx3w5sD8v501Iuyd1v19mPfyhrI5E1E1nl/Xjp5N0/xP2GUBrdkDMxKaxqTPMie/f0dXBUPQQN697a5q+5lBRPhKYOtn6yQKCd9s1Q22nxn72Jmi1RzbMyYJ52FosDT755Qmb46GLrDMaZMQ== -- 2048 -- f058cef4aaa4591c8edd4d0744c82511 -- ssh-rsa --
-- --@xmloutput -- --
-- 192.168.1.1 -- 192.168.1.2 --
-- -- 2c2275604bc33b18a2972c967e28dcdd -- 2048 -- ssh-rsa --
-- -- --
-- 192.168.1.1 -- 192.168.1.2 --
-- -- 60ac4d51b1cd8509121692761d5d276e -- 1024 -- ssh-dss --
-- author = "Sven Klemm" -- comparing keys from known_hosts file added by Piotr Olma and George Chatzisofroniou license = "Same as Nmap--See http://nmap.org/book/man-legal.html" categories = {"safe","default","discovery"} portrule = shortport.port_or_service(22, "ssh") postrule = function() return (nmap.registry.sshhostkey ~= nil) end --- check for the presence of a value in a table --@param tab the table to search into --@param item the searched value --@return a boolean indicating whether the value has been found or not local function contains(tab, item) for _, val in pairs(tab) do if val == item then return true end end return false end --- put hostkey in the nmap registry for usage by other scripts --@param host nmap host table --@param key host key table local add_key_to_registry = function( host, key ) nmap.registry.sshhostkey = nmap.registry.sshhostkey or {} nmap.registry.sshhostkey[host.ip] = nmap.registry.sshhostkey[host.ip] or {} table.insert( nmap.registry.sshhostkey[host.ip], key ) end --- check if there is a key in known_hosts file for the host that's being scanned --- and if there is, compare the keys local function check_keys(host, keys, f) local keys_found = {} for _,k in ipairs(keys) do table.insert(keys_found, k.full_key) end local keys_from_file = {} local same_key, same_key_hashed = {}, {} local hostname = host.name == "" and nil or host.name local possible_host_names = {hostname or nil, host.ip or nil, (hostname and host.ip) and ("%s,%s"):format(hostname, host.ip) or nil} for _p, parts in ipairs(f) do lnumber = parts.linenumber parts = parts.entry local foundhostname = false if #parts >= 3 then -- the line might be hashed if string.match(parts[1], "^|") then -- split the first part of the line - it contains base64'ed salt and hashed hostname local parts_hostname = stdnse.strsplit("|", parts[1]) if #parts_hostname == 4 then -- check if the hash corresponds to the host being scanned local salt = base64.dec(parts_hostname[3]) for _,name in ipairs(possible_host_names) do local hash = base64.enc(openssl.hmac("SHA1", salt, name)) if parts_hostname[4] == hash then stdnse.print_debug(2, "%s: found a hash that matches: %s for hostname: %s", SCRIPT_NAME, hash, name) foundhostname = true table.insert(keys_from_file, {name=name, key=("%s %s"):format(parts[2], parts[3]), lnumber=lnumber}) end end -- Is the key the same but the hashed hostname isn't? if not foundhostname then for _, k in ipairs(keys_found) do if ("%s %s"):format(parts[2], parts[3]) == k then table.insert(same_key_hashed, {lnumber = lnumber}) end end end end else if contains(possible_host_names, parts[1]) then stdnse.print_debug(2, "Found an entry that matches: %s", parts[1]) table.insert(keys_from_file, ("%s %s"):format(parts[2], parts[3])) else -- Is the key the same but the clear text hostname isn't? for _, k in ipairs(keys_found) do if ("%s %s"):format(parts[2], parts[3]) == k then table.insert(same_key, {name=parts[1], key=("%s %s"):format(parts[2], parts[3]), lnumber=lnumber}) end end end end end end local matched_keys, different_keys = {}, {} local matched -- Compare the keys found for this hostname and update the counts. for _,k in ipairs(keys_from_file) do matched = false for __,l in ipairs(keys_found) do if l == k.key then table.insert(matched_keys, k) matched = true end end if not matched then table.insert(different_keys, k) end end -- Start making output. local return_string = "Key comparison with known_hosts file: " if #keys_from_file == 0 then return_string = return_string .. "\n\t" .. "No entry for scanned host found in known_hosts file." else if next(matched_keys) or next(same_key_hashed) or next(same_key) then return_string = return_string .. "\n\tGOOD Matches in known_hosts file: " if next(matched_keys) then for __, gm in ipairs(matched_keys) do return_string = return_string .. "\n\t\tL" .. gm.lnumber .. ": " .. gm.name end end if next(same_key) then for __, gm in ipairs(same_key) do return_string = return_string .. "\n\t\tL" .. gm.lnumber .. ": " .. gm.name end end if next(same_key_hashed) then for __, gm in ipairs(same_key_hashed) do return_string = return_string .. "\n\t\tL" .. gm.lnumber .. ": " end end if different_keys ~= 0 then return_string = return_string .. "\n\tWRONG Matches in known_hosts file: " for __, gm in ipairs(different_keys) do return_string = return_string .. "\n\t\tL" .. gm.lnumber .. ": " .. gm.name end end end end return true, return_string end --- gather host keys --@param host nmap host table --@param port nmap port table of the currently probed port local function portaction(host, port) local output = {} local output_tab = {} local keys = {} local _,key local format = nmap.registry.args.ssh_hostkey or "hex" local all_formats = format:find( 'all', 1, true ) key = ssh1.fetch_host_key( host, port ) if key then table.insert( keys, key ) end key = ssh2.fetch_host_key( host, port, "ssh-dss" ) if key then table.insert( keys, key ) end key = ssh2.fetch_host_key( host, port, "ssh-rsa" ) if key then table.insert( keys, key ) end key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp256" ) if key then table.insert( keys, key ) end key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp384" ) if key then table.insert( keys, key ) end key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp521" ) if key then table.insert( keys, key ) end for _, key in ipairs( keys ) do add_key_to_registry( host, key ) table.insert(output_tab, { fingerprint=stdnse.tohex(key.fingerprint), type=key.key_type, bits=key.bits, key=base64.enc(key.key), }) if format:find( 'hex', 1, true ) or all_formats then table.insert( output, ssh1.fingerprint_hex( key.fingerprint, key.algorithm, key.bits ) ) end if format:find( 'bubble', 1, true ) or all_formats then table.insert( output, ssh1.fingerprint_bubblebabble( openssl.sha1(key.fp_input), key.algorithm, key.bits ) ) end if format:find( 'visual', 1, true ) or all_formats then -- insert empty line so table is not destroyed if this is the first -- line of output if #output == 0 then table.insert( output, " " ) end table.insert( output, ssh1.fingerprint_visual( key.fingerprint, key.algorithm, key.bits ) ) end if nmap.verbosity() > 1 or format:find( 'full', 1, true ) or all_formats then table.insert( output, key.full_key ) end end -- if a known_hosts file was given, then check if it contains a key for the host being scanned local known_hosts = stdnse.get_script_args("ssh-hostkey.known-hosts") or false if known_hosts then known_hosts = ssh1.parse_known_hosts_file(known_hosts) local res, status res, status = check_keys(host, keys, known_hosts) table.insert(output, 1, status) end if #output > 0 then return output_tab, table.concat( output, '\n' ) end end --- check for the presence of a value in a table --@param tab the table to search into --@param item the searched value --@return a boolean indicating whether the value has been found or not local function contains(tab, item) for _, val in pairs(tab) do if val == item then return true end end return false end --- iterate over the list of gathered keys and look for duplicate hosts (sharing the same hostkeys) local function postaction() local hostkeys = {} local output = {} local output_tab = {} local revmap = {} -- create a reverse mapping key_fingerprint -> host(s) for ip, keys in pairs(nmap.registry.sshhostkey) do for _, key in ipairs(keys) do local fp = ssh1.fingerprint_hex(key.fingerprint, key.algorithm, key.bits) if not hostkeys[fp] then hostkeys[fp] = {} revmap[fp] = { fingerprint=stdnse.tohex(key.fingerprint,{separator=":"}), type=key.key_type, bits=key.bits } end -- discard duplicate IPs if not contains(hostkeys[fp], ip) then table.insert(hostkeys[fp], ip) end end end -- look for hosts using the same hostkey for key, hosts in pairs(hostkeys) do if #hostkeys[key] > 1 then table.sort(hostkeys[key], function(a, b) return ipOps.compare_ip(a, "lt", b) end) local str = 'Key ' .. key .. ' used by:' local tab = {key=revmap[key], hosts={}} for _, host in ipairs(hostkeys[key]) do str = str .. '\n ' .. host table.insert(tab.hosts, host) end table.insert(output, str) table.insert(output_tab, tab) end end if #output > 0 then return output_tab, 'Possible duplicate hosts\n' .. table.concat(output, '\n') end end local ActionsTable = { -- portrule: retrieve ssh hostkey portrule = portaction, -- postrule: look for duplicate hosts (same hostkey) postrule = postaction } -- execute the action function corresponding to the current rule action = function(...) return ActionsTable[SCRIPT_TYPE](...) end