--- A XMPP (Jabber) library, implementing a minimal subset of the protocol
-- enough to do authentication brute-force.
--
-- The XML parsing of tags isn't optimal but there's no other easy way
-- (nulls or line-feeds) to match the end of a message. The parse_tag
-- method in the XML class was borrowed from the initial xmpp.nse
-- script written by Vasiliy Kulikov.
--
-- The library consist of the following classes:
-- * <code>XML<code> - containing a minimal XML parser written by
-- Vasiliy Kulikov.
-- * <code>TagProcessor</code> - Contains processing code for common tags
-- * <code>XMPP</code> - containing the low-level functions used to
-- communicate with the Jabber server.
-- * <code>Helper</code> - containing the main interface for script
-- writers
--
-- The following sample illustrates how to use the library to authenticate
-- to a XMPP sever:
-- <code>
-- local helper = xmpp.Helper:new(host, port, options)
-- local status, err = helper:connect()
-- status, err = helper:login(user, pass, "DIGEST-MD5")
-- </code>
--
-- @copyright Same as Nmap--See http://nmap.org/book/man-legal.html
-- @author Patrik Karlsson <patrik@cqure.net>
--
-- Version 0.2
-- Created 07/19/2011 - v0.1 - Created by Patrik Karlsson
-- Revised 07/22/2011 - v0.2 - Added TagProcessors and two new auth mechs:
-- CRAM-MD5 and LOGIN <patrik@cqure.net>
local base64 = require "base64"
local nmap = require "nmap"
local sasl = require "sasl"
local stdnse = require "stdnse"
local string = require "string"
local table = require "table"
_ENV = stdnse.module("xmpp", stdnse.seeall)
XML = {
-- This is a trivial XML processor written by Vasiliy Kulikov. It doesn't
-- fully support XML, but it should be sufficient for the basic XMPP
-- stream handshake. If you see stanzas with uncommon symbols, feel
-- free to enhance these regexps.
parse_tag = function(s)
local _, _, contents, empty, name = string.find(s, "([^<]*)<(/?)([?:%w-]+)")
local attrs = {}
if not name then
return
end
for k, v in string.gmatch(s, "%s([%w:]+)='([^']+)'") do
attrs[k] = v
end
for k, v in string.gmatch(s, "%s([%w:]+)=\"([^\"]+)\"") do
attrs[k] = v
end
local finish = (empty ~= "") or (s:sub(#s-1) == '/>')
return { name = name,
attrs = attrs,
start = (empty == ""),
contents = contents,
finish = finish }
end,
}
TagProcessor = {
["failure"] = function(socket, tag)
return TagProcessor["success"](socket,tag)
end,
["success"] = function(socket, tag)
if ( tag.finish ) then return true end
local newtag
repeat
local status, data = socket:receive_buf(">", true)
if ( not(status) ) then
return false, ("ERROR: Failed to process %s tag"):format(tag.name)
end
newtag = XML.parse_tag(data)
until( newtag.finish and newtag.name == tag.name )
if ( newtag.name == tag.name ) then return true, tag end
return false, ("ERROR: Failed to process %s tag"):format(tag.name)
end,
["challenge"] = function(socket, tag)
local status, data = socket:receive_buf(">", true)
if ( not(status) ) then return false, "ERROR: Failed to read challenge tag" end
local tag = XML.parse_tag(data)
if ( not(status) or tag.name ~= "challenge" ) then
return false, "ERROR: Failed to process challenge"
end
return status, (tag.contents and base64.dec(tag.contents))
end,
}
XMPP = {
--- Creates a new instance of the XMPP class
--
-- @param host table as receieved by the action function
-- @param port table as receieved by the action function
-- @param options table containing options, currently supported
-- <code>timeout</code> - sets the socket timeout
-- <code>servername</code> - sets the server name to use in
-- communication with the server.
-- <code>starttls</code> - start TLS handshake even if it is optional.
new = function(self, host, port, options)
local o = { host = host,
port = port,
options = options or {},
auth = { mechs = {} } }
o.options.timeout = o.options.timeout and o.options.timeout or 10
o.servername = stdnse.get_hostname(host) or o.options.servername
setmetatable(o, self)
self.__index = self
return o
end,
--- Sends data to XMPP server
-- @param data string containing data to send to server
-- @return status true on success false on failure
-- @return err string containing error message
send = function(self, data)
-- this ain't pretty, but we try to "flush" what's left of the receive
-- buffer, prior to send. This way we account for not reading to the
-- end of one message resulting in the next read reading from our
-- previous message.
self.socket:set_timeout(1)
repeat
local status = self.socket:receive_buf("\0", false)
until(not(status))
self.socket:set_timeout(self.options.timeout * 1000)
return self.socket:send(data)
end,
--- Receives a XML tag from the server
--
-- @param tag [optional] if unset, receives the next available tag
-- if set, reads until the given tag has been found
-- @param close [optional] if set, matches a closing tag
receive_tag = function(self, tag, close)
local result
repeat
local status, data = self.socket:receive_buf(">", true)
if ( not(status) ) then return false, data end
result = XML.parse_tag(data)
until( ( not(tag) and (close == nil or result.finish == close ) ) or
( tag == result.name and ( close == nil or result.finish == close ) ) )
return true, result
end,
--- Connects to the XMPP server
-- @return status true on success, false on failure
-- @return err string containing an error message if status is false
connect = function(self)
assert(self.servername,
"Cannot connect to XMPP server without valid server name")
-- we may be reconnecting using SSL
if ( not(self.socket) ) then
self.socket = nmap.new_socket()
self.socket:set_timeout(self.options.timeout * 1000)
local status, err = self.socket:connect(self.host, self.port)
if ( not(status) ) then
return false, err
end
end
local data = ("<?xml version='1.0' ?><stream:stream to='%s' xmlns='jabber:client'" ..
" xmlns:stream='http://etherx.jabber.org/streams'" ..
" version='1.0'>"):format(self.servername)
local status, err = self:send(data)
if ( not(status) ) then return false, "ERROR: Failed to connect to server" end
local version, start_tls
repeat
local status, tag = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to connect to server" end
if ( tag.name == "stream:stream" ) then
version = tag.attrs and tag.attrs.version
elseif ( tag.name == "starttls" and tag.start ) then
status, tag = self:receive_tag()
if ( not(status) ) then
return false, "ERROR: Failed to connect to server"
end
if ( tag.name ~= "starttls" ) then
start_tls = tag.name
else
start_tls = "optional"
end
elseif ( tag.name == "mechanism" and tag.finish ) then
self.auth.mechs[tag.contents] = true
end
until(tag.name == "stream:features" and tag.finish)
if ( version ~= "1.0" ) then
return false, "ERROR: Only version 1.0 is supported"
end
if ( start_tls == "required" or self.options.starttls) then
status, err = self:send("<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>")
if ( not(status) ) then return false, "ERROR: Failed to initiate STARTTLS" end
local status, tag = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to recevice from server" end
if ( tag.name == "proceed" ) then
status, err = self.socket:reconnect_ssl()
self.options.starttls = false
return self:connect()
end
end
return true
end,
--- Logs in to the XMPP server
--
-- @param username string
-- @param password string
-- @param mech string containing a supported authentication mechanism
-- @return status true on success, false on failure
-- @return err string containing error message if status is false
login = function(self, username, password, mech)
assert(mech == "PLAIN" or
mech == "DIGEST-MD5" or
mech == "CRAM-MD5" or
mech == "LOGIN",
"Unsupported authentication mechanism")
local auth = ("<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' " ..
"mechanism='%s'/>"):format(mech)
-- we currently don't do anything with the realm
local realm
-- we need to cut the @domain.tld from the username
if ( username:match("@") ) then
username, realm = username:match("^(.*)@(.*)$")
end
local status, result
if ( mech == "PLAIN" ) then
local mech_params = { username, password }
local auth_data = sasl.Helper:new(mech):encode(table.unpack(mech_params))
auth = ("<auth xmlns='urn:ietf:params:xml:ns:xmpp-sasl' " ..
"mechanism='%s'>%s</auth>"):format(mech, base64.enc(auth_data))
status, result = self.socket:send(auth)
if ( not(status) ) then return false, "ERROR: Failed to send SASL PLAIN authentication" end
status, result = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to receive login response" end
if ( result.name == "failure" ) then
status = TagProcessor[result.name](self.socket, result)
end
else
local status, err = self.socket:send(auth)
if(not(status)) then return false, "ERROR: Failed to initiate SASL login" end
local chall
status, result = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to retrieve challenge" end
status, chall = TagProcessor[result.name](self.socket, result)
if ( mech == "LOGIN" ) then
if ( chall ~= "User Name" ) then
return false, ("ERROR: Login expected 'User Name' received: %s"):format(chall)
end
self.socket:send("<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>" ..
base64.enc(username) ..
"</response>")
status, result = self:receive_tag()
if ( not(status) or result.name ~= "challenge") then
return false, "ERROR: Receiving tag from server"
end
status, chall = TagProcessor[result.name](self.socket, result)
if ( chall ~= "Password" ) then
return false, ("ERROR: Login expected 'Password' received: %s"):format(chall)
end
self.socket:send("<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>" ..
base64.enc(password) ..
"</response>")
status, result = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to receive login challenge" end
if ( result.name == "failure" ) then
status = TagProcessor[result.name](self.socket, result)
return false, "Login failed"
end
else
local mech_params = { username, password, chall, "xmpp", "xmpp/" .. self.servername }
local auth_data = sasl.Helper:new(mech):encode(table.unpack(mech_params))
auth_data = "<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>" ..
base64.enc(auth_data) .. "</response>"
status, err = self.socket:send(auth_data)
-- read to the end tag regardless of what it is
-- it should be one of either: success, challenge or error
repeat
status, result = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to receive login challenge" end
if ( result.name == "failure" ) then
status = TagProcessor[result.name](self.socket, result)
return false, "Login failed"
elseif ( result.name == "success" ) then
status = TagProcessor[result.name](self.socket, result)
if ( not(status) ) then return false, "Failed to process success message" end
return true, "Login success"
elseif ( result.name ~= "challenge" ) then
return false, "ERROR: Failed to receive login challenge"
end
until( result.name == "challenge" and result.finish )
if ( result.name == "challenge" and mech == "DIGEST-MD5" ) then
status, result = self.socket:send("<response xmlns='urn:ietf:params:xml:ns:xmpp-sasl'/>")
if ( not(status) ) then return false, "ERROR: Failed to send DIGEST-MD5 request" end
status, result = self:receive_tag()
if ( not(status) ) then return false, "ERROR: Failed to receive DIGEST-MD5 response" end
end
end
end
if ( result.name == "success" ) then
return true, "Login success"
end
return false, "Login failed"
end,
--- Retrieves the available authentication mechanisms
-- @return table containing all available authentication mechanisms
getAuthMechs = function(self) return self.auth.mechs end,
--- Disconnects the socket from the server
-- @return status true on success, false on failure
disconnect = function(self)
local status, err = self.socket:close()
self.socket = nil
return status, err
end,
}
Helper = {
--- Creates a new Helper instance
-- @param host table as receieved by the action function
-- @param port table as receieved by the action function
-- @param options table containing options, currently supported
-- <code>timeout</code> - sets the socket timeout
-- <code>servername</code> - sets the server name to use in
-- communication with the server.
new = function(self, host, port, options)
local o = { host = host,
port = port,
options = options or {},
xmpp = XMPP:new(host, port, options),
state = "" }
setmetatable(o, self)
self.__index = self
return o
end,
--- Connects to the XMPP server and starts the initial communication
-- @return status true on success, false on failure
-- @return err string containing an error message is status is false
connect = function(self)
if ( not(self.host.targetname) and
not(self.options.servername) ) then
return false, "ERROR: Cannot connect to XMPP server without valid server name"
end
self.state = "CONNECTED"
return self.xmpp:connect()
end,
--- Login to the XMPP server
--
-- @param username string
-- @param password string
-- @param mech string containing a supported authentication mechanism
-- (@see <code>getAuthMechs</code>)
login = function(self, username, password, mech)
return self.xmpp:login(username, password, mech)
end,
--- Retrieves the available authentication mechanisms
-- @return table containing all available authentication mechanisms
getAuthMechs = function(self)
if ( self.state == "CONNECTED" ) then
return self.xmpp:getAuthMechs()
end
return
end,
--- Closes the connection to the server
close = function(self)
self.xmpp:disconnect()
self.state = "DISCONNECTED"
end,
}
return _ENV;
@KyuuKazami