---
-- 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
module(... or "sasl", package.seeall)
local HAVE_SSL = false
require 'stdnse'
require 'base64'
require 'smbauth'
local MECHANISMS = { }
-- 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
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
self.challnvs[name:lower()] = value
start, stop = self.chall:find("%s*,%s*", stop + 1)
if ( not(start) ) then break 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"
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 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")
return response
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
}
if pcall(require, 'openssl') then
HAVE_SSL = true
else
stdnse.print_debug(1,
"sasl.lua: OpenSSL not present, SASL support limited.")
end
if HAVE_SSL then
--- 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,
}