local coroutine = require "coroutine" local io = require "io" local nmap = require "nmap" local shortport = require "shortport" local sslcert = require "sslcert" local stdnse = require "stdnse" local string = require "string" local table = require "table" local tls = require "tls" description = [[ This script repeatedly initiates SSL/TLS connections, each time trying a new cipher or compressor while recording whether a host accepts or rejects it. The end result is a list of all the ciphers and compressors that a server accepts. Each cipher is shown with a strength rating: one of strong, weak, or unknown strength. The output line beginning with Least strength shows the strength of the weakest cipher offered. If you are auditing for weak ciphers, you would want to look more closely at any port where Least strength is not strong. The cipher strength database is in the file nselib/data/ssl-ciphers, or you can use a different file through the script argument ssl-enum-ciphers.rankedcipherlist. SSLv3/TLSv1 requires more effort to determine which ciphers and compression methods a server supports than SSLv2. A client lists the ciphers and compressors that it is capable of supporting, and the server will respond with a single cipher and compressor chosen, or a rejection notice. This script is intrusive since it must initiate many connections to a server, and therefore is quite noisy. ]] --- -- @usage -- nmap --script ssl-enum-ciphers -p 443 -- -- @args ssl-enum-ciphers.rankedcipherlist A path to a file of cipher names and strength ratings -- -- @output -- PORT STATE SERVICE REASON -- 443/tcp open https syn-ack -- | ssl-enum-ciphers: -- | SSLv3 -- | Ciphers (6) -- | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA - unknown strength -- | TLS_DHE_RSA_WITH_AES_128_CBC_SHA - strong -- | TLS_DHE_RSA_WITH_AES_256_CBC_SHA - unknown strength -- | TLS_RSA_WITH_3DES_EDE_CBC_SHA - strong -- | TLS_RSA_WITH_AES_128_CBC_SHA - strong -- | TLS_RSA_WITH_AES_256_CBC_SHA - unknown strength -- | Compressors (1) -- | uncompressed -- | TLSv1.0 -- | Ciphers (6) -- | TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA - unknown strength -- | TLS_DHE_RSA_WITH_AES_128_CBC_SHA - strong -- | TLS_DHE_RSA_WITH_AES_256_CBC_SHA - unknown strength -- | TLS_RSA_WITH_3DES_EDE_CBC_SHA - strong -- | TLS_RSA_WITH_AES_128_CBC_SHA - strong -- | TLS_RSA_WITH_AES_256_CBC_SHA - unknown strength -- | Compressors (1) -- | uncompressed -- |_ Least strength = unknown strength -- -- @xmloutput -- --
--
-- strong -- TLS_RSA_WITH_3DES_EDE_CBC_SHA --
-- -- weak -- TLS_RSA_WITH_DES_CBC_SHA --
-- -- strong -- TLS_RSA_WITH_RC4_128_MD5 --
-- -- strong -- TLS_RSA_WITH_RC4_128_SHA --
-- -- -- NULL --
-- -- --
--
-- strong -- TLS_RSA_WITH_3DES_EDE_CBC_SHA --
-- -- weak -- TLS_RSA_WITH_DES_CBC_SHA --
-- -- strong -- TLS_RSA_WITH_RC4_128_MD5 --
-- -- strong -- TLS_RSA_WITH_RC4_128_SHA --
-- -- -- NULL --
-- -- weak author = "Mak Kolybabi , Gabriel Lawrence" license = "Same as Nmap--See http://nmap.org/book/man-legal.html" categories = {"discovery", "intrusive"} -- Test this many ciphersuites at a time. -- http://seclists.org/nmap-dev/2012/q3/156 -- http://seclists.org/nmap-dev/2010/q1/859 local CHUNK_SIZE = 64 cipherstrength = { ["broken"] = 0, ["weak"] = 1, ["unknown strength"] = 2, ["strong"] = 3 } local rankedciphers={} local mincipherstrength=9999 --artificial "highest value" local rankedciphersfilename=false local function try_params(host, port, t) local buffer, err, i, record, req, resp, sock, status -- Create socket. local specialized = sslcert.getPrepareTLSWithoutReconnect(port) if specialized then local status status, sock = specialized(host, port) if not status then stdnse.print_debug(1, "Can't connect: %s", err) return nil end else sock = nmap.new_socket() sock:set_timeout(5000) local status = sock:connect(host, port) if not status then stdnse.print_debug(1, "Can't connect: %s", err) sock:close() return nil end end sock:set_timeout(5000) -- Send request. req = tls.client_hello(t) status, err = sock:send(req) if not status then stdnse.print_debug(1, "Can't send: %s", err) sock:close() return nil end -- Read response. buffer = "" record = nil while true do local status status, buffer, err = tls.record_buffer(sock, buffer, 1) if not status then stdnse.print_debug(1, "Couldn't read a TLS record: %s", err) return nil end -- Parse response. i, record = tls.record_read(buffer, 1) if record and record.type == "alert" and record.body[1].level == "warning" then stdnse.print_debug(1, "Ignoring warning: %s", record.body[1].description) -- Try again. elseif record then sock:close() return record end buffer = buffer:sub(i+1) end end local function keys(t) local ret = {} for k, _ in pairs(t) do ret[#ret+1] = k end return ret end local function in_chunks(t, size) local ret = {} for i = 1, #t, size do local chunk = {} for j = i, i + size - 1 do chunk[#chunk+1] = t[j] end ret[#ret+1] = chunk end return ret end local function remove(t, e) for i, v in ipairs(t) do if v == e then table.remove(t, i) return i end end return nil end local function find_ciphers(host, port, protocol) local name, protocol_worked, record, results, t,cipherstr local ciphers = in_chunks(keys(tls.CIPHERS), CHUNK_SIZE) local t = { ["protocol"] = protocol, ["extensions"] = { -- Claim to support every elliptic curve ["elliptic_curves"] = tls.EXTENSION_HELPERS["elliptic_curves"](keys(tls.ELLIPTIC_CURVES)), -- Claim to support every EC point format ["ec_point_formats"] = tls.EXTENSION_HELPERS["ec_point_formats"](keys(tls.EC_POINT_FORMATS)), }, } if host.targetname then t["extensions"]["server_name"] = tls.EXTENSION_HELPERS["server_name"](host.targetname) end results = {} -- Try every cipher. protocol_worked = false for _, group in ipairs(ciphers) do while (next(group)) do -- Create structure. t["ciphers"] = group record = try_params(host, port, t) if record == nil then if protocol_worked then stdnse.print_debug(2, "%d ciphers rejected. (No handshake)", #group) else stdnse.print_debug(1, "%d ciphers and/or protocol %s rejected. (No handshake)", #group, protocol) end break elseif record["protocol"] ~= protocol then stdnse.print_debug(1, "Protocol %s rejected.", protocol) protocol_worked = nil break elseif record["type"] == "alert" and record["body"][1]["description"] == "handshake_failure" then protocol_worked = true stdnse.print_debug(2, "%d ciphers rejected.", #group) break elseif record["type"] ~= "handshake" or record["body"][1]["type"] ~= "server_hello" then stdnse.print_debug(2, "Unexpected record received.") break else protocol_worked = true name = record["body"][1]["cipher"] stdnse.print_debug(2, "Cipher %s chosen.", name) remove(group, name) -- Add cipher to the list of accepted ciphers. table.insert(results, name) end end if protocol_worked == nil then return nil end end if not protocol_worked then return nil end return results end local function find_compressors(host, port, protocol, good_cipher) local name, protocol_worked, record, results, t local compressors = keys(tls.COMPRESSORS) local t = { ["protocol"] = protocol, ["ciphers"] = {good_cipher}, ["extensions"] = { -- Claim to support every elliptic curve ["elliptic_curves"] = tls.EXTENSION_HELPERS["elliptic_curves"](keys(tls.ELLIPTIC_CURVES)), -- Claim to support every EC point format ["ec_point_formats"] = tls.EXTENSION_HELPERS["ec_point_formats"](keys(tls.EC_POINT_FORMATS)), }, } if host.targetname then t["extensions"]["server_name"] = tls.EXTENSION_HELPERS["server_name"](host.targetname) end results = {} -- Try every compressor. protocol_worked = false while (next(compressors)) do -- Create structure. t["compressors"] = compressors -- Try connecting with compressor. record = try_params(host, port, t) if record == nil then if protocol_worked then stdnse.print_debug(2, "%d compressors rejected. (No handshake)", #compressors) else stdnse.print_debug(1, "%d compressors and/or protocol %s rejected. (No handshake)", #compressors, protocol) end break elseif record["protocol"] ~= protocol then stdnse.print_debug(1, "Protocol %s rejected.", protocol) break elseif record["type"] == "alert" and record["body"][1]["description"] == "handshake_failure" then protocol_worked = true stdnse.print_debug(2, "%d compressors rejected.", #compressors) break elseif record["type"] ~= "handshake" or record["body"][1]["type"] ~= "server_hello" then stdnse.print_debug(2, "Unexpected record received.") break else protocol_worked = true name = record["body"][1]["compressor"] stdnse.print_debug(2, "Compressor %s chosen.", name) remove(compressors, name) -- Add compressor to the list of accepted compressors. table.insert(results, name) if name == "NULL" then break -- NULL is always last choice, and must be included end end end return results end local function try_protocol(host, port, protocol, upresults) local ciphers, compressors, results local condvar = nmap.condvar(upresults) results = stdnse.output_table() -- Find all valid ciphers. ciphers = find_ciphers(host, port, protocol) if ciphers == nil then condvar "signal" return nil end if #ciphers == 0 then results = {ciphers={},compressors={}} setmetatable(results,{ __tostring=function(t) return "No supported ciphers found" end }) upresults[protocol] = results condvar "signal" return nil end -- Find all valid compression methods. compressors = find_compressors(host, port, protocol, ciphers[1]) -- Add rankings to ciphers local cipherstr for i, name in ipairs(ciphers) do if rankedciphersfilename and rankedciphers[name] then cipherstr=rankedciphers[name] else cipherstr="unknown strength" end stdnse.print_debug(2, "Strength of %s rated %d.",cipherstr,cipherstrength[cipherstr]) if mincipherstrength>cipherstrength[cipherstr] then stdnse.print_debug(2, "Downgrading min cipher strength to %d.",cipherstrength[cipherstr]) mincipherstrength=cipherstrength[cipherstr] end local outcipher = {name=name, strength=cipherstr} setmetatable(outcipher,{ __tostring=function(t) return string.format("%s - %s", t.name, t.strength) end }) ciphers[i]=outcipher end -- Format the cipher table. table.sort(ciphers, function(a, b) return a["name"] < b["name"] end) results["ciphers"] = ciphers -- Format the compressor table. table.sort(compressors) results["compressors"] = compressors upresults[protocol] = results condvar "signal" return nil end -- Shamelessly stolen from nselib/unpwdb.lua and changed a bit. (Gabriel Lawrence) local filltable = function(filename,table) if #table ~= 0 then return true end local file = io.open(filename, "r") if not file then return false end while true do local l = file:read() if not l then break end -- Comments takes up a whole line if not l:match("#!comment:") then local lsplit=stdnse.strsplit("%s+", l) if cipherstrength[lsplit[2]] then table[lsplit[1]] = lsplit[2] else stdnse.print_debug(1,"Strength not defined, ignoring: %s:%s",lsplit[1],lsplit[2]) end end end file:close() return true end portrule = function (host, port) return shortport.ssl(host, port) or sslcert.getPrepareTLSWithoutReconnect(port) end --- Return a table that yields elements sorted by key when iterated over with pairs() -- Should probably put this in a formatting library later. -- Depends on keys() function defined above. --@param t The table whose data should be used --@return out A table that can be passed to pairs() to get sorted results function sorted_by_key(t) local out = {} setmetatable(out, { __pairs = function(_) local order = keys(t) table.sort(order) return coroutine.wrap(function() for i,k in ipairs(order) do coroutine.yield(k, t[k]) end end) end }) return out end action = function(host, port) local name, result, results rankedciphersfilename=stdnse.get_script_args("ssl-enum-ciphers.rankedcipherlist") if rankedciphersfilename then filltable(rankedciphersfilename,rankedciphers) else rankedciphersfilename = nmap.fetchfile( "nselib/data/ssl-ciphers" ) stdnse.print_debug(1, "Ranked ciphers filename: %s", rankedciphersfilename) filltable(rankedciphersfilename,rankedciphers) end results = {} local condvar = nmap.condvar(results) local threads = {} for name, _ in pairs(tls.PROTOCOLS) do stdnse.print_debug(1, "Trying protocol %s.", name) local co = stdnse.new_thread(try_protocol, host, port, name, results) threads[co] = true end repeat for thread in pairs(threads) do if coroutine.status(thread) == "dead" then threads[thread] = nil end end if ( next(threads) ) then condvar "wait" end until next(threads) == nil if #( keys(results) ) == 0 then return nil end if rankedciphersfilename then for k, v in pairs(cipherstrength) do if v == mincipherstrength then -- Should sort before or after SSLv3, TLSv* results["least strength"] = k end end end return sorted_by_key(results) end