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sasl.lua
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--- -- Simple Authentication and Security Layer (SASL). -- -- The library contains some low level functions and a high level class. -- -- The <code>DigestMD5</code> class contains all code necessary to calculate -- a DIGEST-MD5 response based on the servers challenge and the other -- necessary arguments (@see DigestMD5.new). -- It can be called throught the SASL helper or directly like this: -- <code> -- local dmd5 = DigestMD5:new(chall, user, pass, "AUTHENTICATE", nil, "imap") -- local digest = dmd5:calcDigest() -- </code> -- -- The <code>NTLM</code> class contains all code necessary to calculate a -- NTLM response based on the servers challenge and the other necessary -- arguments (@see NTLM.new). It can be called through the SASL helper or -- directly like this: -- <code> -- local ntlm = NTLM:new(chall, user, pass) -- local response = ntlm:calcResponse() -- </code> -- -- The Helper class contains the high level methodes: -- * <code>new</code>: This is the SASL object constructor. -- * <code>set_mechanism</code>: Sets the authentication mechanism to use. -- * <code>set_callback</code>: Sets the encoding function to use. -- * <code>encode</code>: Encodes the parameters according to the -- authentication mechanism. -- * <code>reset_callback</code>: Resets the authentication function. -- * <code>reset</code>: Resets the SASL object. -- -- The script writers should use the Helper class to create SASL objects, -- and they can also use the low level functions to customize their -- encoding functions. -- -- @copyright Same as Nmap--See http://nmap.org/book/man-legal.html -- Version 0.2 -- Created 07/17/2011 - v0.1 - Created by Djalal Harouini -- Revised 07/18/2011 - v0.2 - Added NTLM, DIGEST-MD5 classes local bin = require "bin" local bit = require "bit" local smbauth = require "smbauth" local stdnse = require "stdnse" local string = require "string" _ENV = stdnse.module("sasl", stdnse.seeall) local HAVE_SSL, openssl = pcall(require, 'openssl') if ( not(HAVE_SSL) ) then stdnse.print_debug(1, "sasl.lua: OpenSSL not present, SASL support limited.") end local MECHANISMS = { } if HAVE_SSL then -- Calculates a DIGEST MD5 response DigestMD5 = { --- Instantiates DigestMD5 -- -- @param chall string containing the base64 decoded challenge -- @return a new instance of DigestMD5 new = function(self, chall, username, password, method, uri, service, realm) local o = { nc = 0, chall = chall, challnvs = {}, username = username, password = password, method = method, uri = uri, service = service, realm = realm } setmetatable(o, self) self.__index = self o:parseChallenge() return o end, -- parses a challenge received from the server -- takes care of both quoted and unqoted identifiers -- regardless of what RFC says parseChallenge = function(self) local results = {} local start, stop = 0,0 if self.chall then while(true) do local name, value start, stop, name = self.chall:find("([^=]*)=%s*", stop + 1) if ( not(start) ) then break end if ( self.chall:sub(stop + 1, stop + 1) == "\"" ) then start, stop, value = self.chall:find("(.-)\"", stop + 2) else start, stop, value = self.chall:find("([^,]*)", stop + 1) end name = name:lower() if name == "digest realm" then name="realm" end self.challnvs[name] = value start, stop = self.chall:find("%s*,%s*", stop + 1) if ( not(start) ) then break end end end end, --- Calculates the digest calcDigest = function( self ) local uri = self.uri or ("%s/%s"):format(self.service, "localhost") local realm = self.realm or self.challnvs.realm or "" local cnonce = stdnse.tohex(openssl.rand_bytes( 8 )) local qop = "auth" local qop_not_specified if self.challnvs.qop then qop_not_specified = false else qop_not_specified = true end self.nc = self.nc + 1 local A1_part1 = openssl.md5(self.username .. ":" .. (self.challnvs.realm or "") .. ":" .. self.password) local A1 = stdnse.tohex(openssl.md5(A1_part1 .. ":" .. self.challnvs.nonce .. ':' .. cnonce)) local A2 = stdnse.tohex(openssl.md5(("%s:%s"):format(self.method, uri))) local digest = stdnse.tohex(openssl.md5(A1 .. ":" .. self.challnvs.nonce .. ":" .. ("%08d"):format(self.nc) .. ":" .. cnonce .. ":" .. qop .. ":" .. A2)) local b1 if not self.challnvs.algorithm or self.challnvs.algorithm == "MD5" then b1 = stdnse.tohex(openssl.md5(self.username..":"..(self.challnvs.realm or "")..":"..self.password)) else b1 = A1 end -- should we make it work when qop == "auth-int" (we would need entity-body here, which -- might be complicated)? local digest_http if not qop_not_specified then digest_http = stdnse.tohex(openssl.md5(b1 .. ":" .. self.challnvs.nonce .. ":" .. ("%08d"):format(self.nc) .. ":" .. cnonce .. ":" .. qop .. ":" .. A2)) else digest_http = stdnse.tohex(openssl.md5(b1 .. ":" .. self.challnvs.nonce .. ":" .. A2)) end local response = "username=\"" .. self.username .. "\"" response = response .. (",%s=\"%s\""):format("realm", realm) response = response .. (",%s=\"%s\""):format("nonce", self.challnvs.nonce) response = response .. (",%s=\"%s\""):format("cnonce", cnonce) response = response .. (",%s=%08d"):format("nc", self.nc) response = response .. (",%s=%s"):format("qop", "auth") response = response .. (",%s=\"%s\""):format("digest-uri", uri) response = response .. (",%s=%s"):format("response", digest) response = response .. (",%s=%s"):format("charset", "utf-8") -- response_table is used in http library because the request should -- be a little bit different then the string generated above local response_table = { username = self.username, realm = realm, nonce = self.challnvs.nonce, cnonce = cnonce, nc = ("%08d"):format(self.nc), qop = qop, ["digest-uri"] = uri, algorithm = self.challnvs.algorithm, response = digest_http } return response, response_table end, } -- The NTLM class handling NTLM challenge response authentication NTLM = { --- Creates a new instance of the NTLM class -- -- @param chall string containing the challenge received from the server -- @param username string containing the username -- @param password string containing the password -- @return new instance of NTML new = function(self, chall, username, password) local o = { nc = 0, chall = chall, username = username, password = password} setmetatable(o, self) self.__index = self o:parseChallenge() return o end, --- Converst str to "unicode" (adds null bytes for every other byte) -- @param str containing string to convert -- @return unicode string containing the unicoded str to_unicode = function(str) local unicode = "" for i = 1, #str, 1 do unicode = unicode .. bin.pack("<S", string.byte(str, i)) end return unicode end, --- Parses the NTLM challenge as received from the server parseChallenge = function(self) local NTLM_NegotiateUnicode = 0x00000001 local NTLM_NegotiateExtendedSecurity = 0x00080000 local pos, _, message_type pos, _, message_type, _, _, _, self.flags, self.chall, _, _, _, _ = bin.unpack("<A8ISSIIA8LSSI", self.chall) if ( message_type ~= 0x02 ) then error("NTLM parseChallenge expected message type: 0x02") end self.is_extended = ( bit.band(self.flags, NTLM_NegotiateExtendedSecurity) == NTLM_NegotiateExtendedSecurity ) local is_unicode = ( bit.band(self.flags, NTLM_NegotiateUnicode) == NTLM_NegotiateUnicode ) self.workstation = "NMAP-HOST" self.domain = self.username:match("^(.-)\\(.*)$") or "DOMAIN" if ( is_unicode ) then self.workstation = self.to_unicode(self.workstation) self.username = self.to_unicode(self.username) self.domain = self.to_unicode(self.domain) end end, --- Calculates the response calcResponse = function(self) local ntlm, lm = smbauth.get_password_response(nil, self.username, self.domain, self.password, nil, "v1", self.chall, self.is_extended) local msg_type = 3 local response local BASE_OFFSET = 72 local offset local encrypted_random_sesskey = "" local flags = 0xa2888205 -- (NTLM_NegotiateUnicode | \ -- NTLM_RequestTarget | \ -- NTLM_NegotiateNTLM | \ -- NTLM_NegotiateAlwaysSign | \ -- NTLM_NegotiateExtendedSecurity | \ -- NTLM_NegotiateTargetInfo | \ -- NTLM_NegotiateVersion | \ -- NTLM_Negotiate128 | \ -- NTLM_Negotiate56) response = bin.pack("<AI", "NTLMSSP\0", msg_type) offset = BASE_OFFSET + #self.workstation + #self.username + #self.domain response = response .. bin.pack("<SSI", #lm, #lm, offset) offset = offset + #lm response = response .. bin.pack("<SSI", #ntlm, #ntlm, offset) offset = BASE_OFFSET response = response .. bin.pack("<SSI", #self.domain, #self.domain, offset) offset = BASE_OFFSET + #self.domain response = response .. bin.pack("<SSI", #self.username, #self.username, offset) offset = BASE_OFFSET + #self.domain + #self.username response = response .. bin.pack("<SSI", #self.workstation, #self.workstation, offset) offset = offset + #self.workstation + #lm + #ntlm response = response .. bin.pack("<SSI", #encrypted_random_sesskey, #encrypted_random_sesskey, offset) response = response .. bin.pack("<I", flags) -- add version info (major 5, minor 1, build 2600, reserved(1-3) 0, -- NTLM Revision 15) response = response .. bin.pack("<CCSCCCC", 5, 1, 2600, 0, 0, 0, 15) response = response .. self.domain .. self.username .. self.workstation .. ntlm .. lm .. encrypted_random_sesskey return response end } --- Encodes the parameters using the <code>CRAM-MD5</code> mechanism. -- -- @param username string. -- @param password string. -- @param challenge The challenge as it is returned by the server. -- @return string The encoded string on success, or nil if Nmap was -- compiled without OpenSSL. function cram_md5_enc(username, password, challenge) local encode = stdnse.tohex(openssl.hmac('md5', password, challenge)) return username.." "..encode end --- Encodes the parameters using the <code>DIGEST-MD5</code> mechanism. -- -- @param username string. -- @param password string. -- @param challenge The challenge as it is returned by the server. -- @param service string containing the service that is requesting the -- encryption (eg. POP, IMAP, STMP) -- @param uri string containing the URI -- @return string The encoded string on success, or nil if Nmap was -- compiled without OpenSSL. function digest_md5_enc(username, password, challenge, service, uri) return DigestMD5:new(challenge, username, password, "AUTHENTICATE", uri, service):calcDigest() end function ntlm_enc(username, password, challenge) return NTLM:new(challenge, username, password):calcResponse() end else function cram_md5_enc() error("cram_md5_enc not supported without OpenSSL") end function digest_md5_enc() error("digest_md5_enc not supported without OpenSSL") end function ntlm_enc() error("ntlm_enc not supported without OpenSSL") end end MECHANISMS["CRAM-MD5"] = cram_md5_enc MECHANISMS["DIGEST-MD5"] = digest_md5_enc MECHANISMS["NTLM"] = ntlm_enc --- Encodes the parameters using the <code>PLAIN</code> mechanism. -- -- @param username string. -- @param password string. -- @return string The encoded string. function plain_enc(username, password) return username.."\0"..username.."\0"..password end MECHANISMS["PLAIN"] = plain_enc --- Checks if the given mechanism is supported by this library. -- -- @param mechanism string to check. -- @return mechanism if it is supported, otherwise nil. -- @return callback The mechanism encoding function on success. function check_mechanism(mechanism) local lmech, lcallback if mechanism then mechanism = string.upper(mechanism) if MECHANISMS[mechanism] then lmech = mechanism lcallback = MECHANISMS[mechanism] else stdnse.print_debug(3, "sasl library does not support '%s' mechanism", mechanism) end end return lmech, lcallback end --- This is the SASL Helper class, script writers should use it to create -- SASL objects. -- -- Usage of the Helper class: -- -- local sasl_enc = sasl.Helper.new("CRAM-MD5") -- local result = sasl_enc:encode(username, password, challenge) -- -- sasl_enc:set_mechanism("LOGIN") -- local user, pass = sasl_enc:encode(username, password) Helper = { --- SASL object constructor. -- -- @param mechanism The authentication mechanism to use -- (optional parameter). -- @param callback The encoding function associated with the -- mechanism (optional parameter). -- @usage -- local sasl_enc = sasl.Helper:new() -- local sasl_enc = sasl.Helper:new("CRAM-MD5") -- local sasl_enc = sasl.Helper:new("CRAM-MD5", my_cram_md5_func) -- @return sasl object. new = function(self, mechanism, callback) local o = {} setmetatable(o, self) self.__index = self if self:set_mechanism(mechanism) then self:set_callback(callback) end return o end, --- Sets the SASL mechanism to use. -- -- @param string The authentication mechanism. -- @usage -- local sasl_enc = sasl.Helper:new() -- sasl_enc:set_mechanism("CRAM-MD5") -- sasl_enc:set_mechanism("PLAIN") -- @return mechanism on success, or nil if the mechanism is not -- supported. set_mechanism = function(self, mechanism) self.mechanism, self.callback = check_mechanism(mechanism) return self.mechanism end, --- Associates A custom encoding function with the authentication -- mechanism. -- -- Note that the SASL object by default will have its own -- callback functions. -- -- @param callback The function associated with the authentication -- mechanism. -- @usage -- -- My personal CRAM-MD5 encode function -- function cram_md5_encode_func(username, password, challenge) -- ... -- end -- local sasl_enc = sasl.Helper:new("CRAM-MD5") -- sasl_enc:set_callback(cram_md5_handle_func) -- local result = sasl_enc:encode(username, password, challenge) set_callback = function(self, callback) if callback then self.callback = callback end end, --- Resets the encoding function to the default SASL -- callback function. reset_callback = function(self) self.callback = MECHANISMS[self.mechanism] end, --- Resets all the data of the SASL object. -- -- This methode will clear the specified SASL mechanism. reset = function(self) self:set_mechanism() end, --- Returns the current authentication mechanism. -- -- @return mechanism on success, or nil on failures. get_mechanism = function(self) return self.mechanism end, --- Encodes the parameters according to the specified mechanism. -- -- @param ... The parameters to encode. -- @usage -- local sasl_enc = sasl.Helper:new("CRAM-MD5") -- local result = sasl_enc:encode(username, password, challenge) -- local sasl_enc = sasl.Helper:new("PLAIN") -- local result = sasl_enc:encode(username, password) -- @return string The encoded string on success, or nil on failures. encode = function(self, ...) return self.callback(...) end, } return _ENV;