cics-user-brute
NSE detection rule by Philip Young aka Soldier of Fortran · Same as Nmap--See https://nmap.org/book/man-legal.html
CICS User ID brute forcing script for the CESL login screen.
local nmap = require "nmap"
local string = require "string"
local stringaux = require "stringaux"
local stdnse = require "stdnse"
local shortport = require "shortport"
local tn3270 = require "tn3270"
local brute = require "brute"
local creds = require "creds"
local unpwdb = require "unpwdb"
description = [[
CICS User ID brute forcing script for the CESL login screen.
]]
---
-- @args cics-user-brute.commands Commands in a semi-colon separated list needed
-- to access CICS. Defaults to <code>CICS</code>.
--
-- @usage
-- nmap --script=cics-user-brute -p 23 <targets>
--
-- nmap --script=cics-user-brute --script-args userdb=users.txt,
-- cics-user-brute.commands="exit;logon applid(cics42)" -p 23 <targets>
--
-- @output
-- PORT STATE SERVICE
-- 23/tcp open tn3270
-- | cics-user-brute:
-- | Accounts:
-- | PLAGUE: Valid - CICS User ID
-- |_ Statistics: Performed 31 guesses in 114 seconds, average tps: 0
-- @changelog
-- 2016-08-29 - v0.1 - created by Soldier of Fortran
-- 2016-10-26 - v0.2 - Added RACF support
-- 2017-01-23 - v0.3 - Rewrote script to use fields and skip enumeration to speed up testing
-- 2019-02-01 - v0.4 - Disabled new TN3270E support
author = "Philip Young aka Soldier of Fortran"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"intrusive", "brute"}
portrule = shortport.port_or_service({23,992}, "tn3270")
--- Registers User IDs that no longer need to be tested
--
-- @param username to stop checking
local function register_invalid( username )
if nmap.registry.cicsinvalid == nil then
nmap.registry.cicsinvalid = {}
end
stdnse.debug(2,"Registering %s", username)
nmap.registry.cicsinvalid[username] = true
end
Driver = {
new = function(self, host, port, options)
local o = {}
setmetatable(o, self)
self.__index = self
o.host = host
o.port = port
o.options = options
o.tn3270 = tn3270.Telnet:new(brute.new_socket())
o.tn3270:disable_tn3270e()
return o
end,
connect = function( self )
local status, err = self.tn3270:initiate(self.host,self.port)
self.tn3270:get_screen_debug(2)
if not status then
stdnse.debug("Could not initiate TN3270: %s", err )
return false
end
stdnse.debug(2,"Connect Successful")
return true
end,
disconnect = function( self )
self.tn3270:disconnect()
self.tn3270 = nil
return true
end,
login = function (self, user, pass)
local commands = self.options['key1']
local timeout = 300
local max_blank = 1
local loop = 1
local err
stdnse.debug(2,"Getting to CICS")
local run = stringaux.strsplit(";%s*", commands)
for i = 1, #run do
stdnse.debug(2,"Issuing Command (#%s of %s): %s", i, #run ,run[i])
self.tn3270:send_cursor(run[i])
self.tn3270:get_all_data()
self.tn3270:get_screen_debug(2)
end
-- Are we at the logon transaction?
if not (self.tn3270:find('SIGN ON TO CICS') or self.tn3270:find("Signon to CICS")) then
-- We might be at some weird screen, lets try and exit it then clear it out
stdnse.debug(2,"Sending: F3")
self.tn3270:send_pf(3) -- send F3
self.tn3270:get_all_data()
stdnse.debug(2,"Clearing the Screen")
self.tn3270:send_clear()
self.tn3270:get_all_data()
self.tn3270:get_screen_debug(2)
stdnse.debug(2,"Sending 'CESL'")
self.tn3270:send_cursor('CESL')
self.tn3270:get_all_data()
-- Have we encoutered a slow system?
if self.tn3270:isClear() then
self.tn3270:get_all_data(1000)
end
self.tn3270:get_screen_debug(2)
end
-- At this point we MUST be at CESL to try accounts.
-- If we're not then we quit with an error
if not (self.tn3270:find('SIGN ON TO CICS') or self.tn3270:find("Signon to CICS")) then
local err = brute.Error:new( "Can't get to CESL")
err:setRetry( true )
return false, err
end
-- Ok we're good we're at CESL. Send the Userid and Password.
local fields = self.tn3270:writeable() -- Get the writeable field areas
local user_loc = {fields[2][1],user} -- This is the 'UserID:' field
local pass_loc = {fields[4][1],pass} -- This is the 'Password:' field ([2] is a group ID)
stdnse.verbose('[BRUTE] Trying CICS: ' .. user ..' : ' .. pass)
stdnse.debug(3,"[BRUTE] Location:" .. fields[2][1] .. " x " .. fields[4][1])
self.tn3270:send_locations({user_loc,pass_loc})
self.tn3270:get_all_data()
stdnse.debug(2,"Screen Received for User ID: %s/%s", user, pass)
self.tn3270:get_screen_debug(2)
local loop = 1
while loop < 300 and self.tn3270:find('DFHCE3520') do -- still at Enter UserID message?
stdnse.verbose('Trying CICS: ' .. user ..' : ' .. pass)
self.tn3270:send_locations({user_loc,pass_loc})
self.tn3270:get_all_data()
stdnse.debug(2,"Screen Received for User ID: %s/%s", user, pass)
self.tn3270:get_screen_debug(2)
loop = loop + 1 -- We don't want this to loop forever
end
if loop == 300 then
local err = brute.Error:new( "Error with UserID entry")
err:setRetry( true )
return false, err
end
-- Now check what we received if its valid or not
if self.tn3270:find('TSS7101E') or
self.tn3270:find('DFHCE3530') or
self.tn3270:find('DFHCE3532') then
-- Top Secret:
-- TSS7101E Password is Incorrect
-- RACF:
-- DFHCE3530/2 Your userid or password is invalid. Please retype both.
return false, brute.Error:new( "Incorrect password" )
elseif self.tn3270:find('TSS7145E') or
self.tn3270:find("TSS714[0-3]E") or
self.tn3270:find('TSS7160E') or
self.tn3270:find('TSS7120E') then
-- Top Secret:
-- TSS7140E Accessor ID Has Expired: No Longer Valid
-- TSS7141E Use of Accessor ID Suspended
-- TSS7142E Accessor ID Not Yet Available for Use - Still Inactive
-- TSS7143E Accessor ID Has Been Inactive Too Long
-- TSS7120E PASSWORD VIOLATION THRESHOLD EXCEEDED
-- TSS7145E ACCESSOR ID <acid> NOT DEFINED TO SECURITY
-- TSS7160E Facility <X> Not Authorized for Your Use
-- Store the invalid ID in the registry so we don't keep trying it with subsequent passwords
-- when using default brute library.
register_invalid(user)
return false, brute.Error:new( "User ID Not Able to Use CICS" )
elseif self.tn3270:find("DFHCE3549") or
self.tn3270:find('TSS7000I') or
self.tn3270:find('TSS7110E Password Has Expired. New Password Missing') or
self.tn3270:find('TSS7001I') then
stdnse.verbose("Valid CICS UserID / Password: " .. user .. "/" .. pass)
return true, creds.Account:new(user, pass, creds.State.VALID)
else
-- ok whoa, something happened, print the screen but don't store as valid
stdnse.verbose("Valid(?) user/pass with current output " .. user .. "/" .. pass .. "\n" .. self.tn3270:get_screen())
return false, brute.Error:new( "Incorrect password" )
end
return false, brute.Error:new("Something went wrong, we didn't get a proper response")
end
}
--- Tests the target to see if we can even get to CICS
--
-- @param host host NSE object
-- @param port port NSE object
-- @param commands optional script-args of commands to use to get to CICS
-- @return status true on success, false on failure
local function cics_test( host, port, commands )
stdnse.verbose(2,"Checking for CICS Login Page")
local tn = tn3270.Telnet:new()
tn:disable_tn3270e()
local status, err = tn:initiate(host,port)
local cesl = false -- initially we're not at CICS
if not status then
stdnse.debug("Could not initiate TN3270: %s", err )
return false
end
tn:get_screen_debug(2) -- prints TN3270 screen to debug
stdnse.debug(2,"Getting to CICS")
local run = stringaux.strsplit(";%s*", commands)
for i = 1, #run do
stdnse.debug(2,"Issuing Command (#%s of %s): %s", i, #run ,run[i])
tn:send_cursor(run[i])
tn:get_all_data()
tn:get_screen_debug(2)
end
tn:get_all_data()
tn:get_screen_debug(2) -- for debug purposes
-- We should now be at CICS. Check if we're already at the logon screen
if tn:find('SIGN ON TO CICS') and tn:find("Signon to CICS") then
stdnse.verbose(2,"At CICS Login Transaction (CESL)")
tn:disconnect()
return true
end
-- Uh oh. We're not at the logon screen. Now we need to send:
-- * F3 to exit the CICS program
-- * CLEAR (a tn3270 command) to clear the screen.
-- (you need to clear before sending a transaction ID)
-- * a known default CICS transaction ID with predictable outcome
-- (CESF with 'Sign-off is complete.' as the result)
-- to confirm that we were in CICS. If so we return true
-- otherwise we return false
local count = 1
while not tn:isClear() and count < 6 do
-- some systems will just kick you off others are slow in responding
-- this loop continues to try getting out of whatever transaction 5 times. If it can't
-- then we probably weren't in CICS to begin with.
stdnse.debug(2,"Sending: F3")
tn:send_pf(3) -- send F3
tn:get_all_data()
stdnse.debug(2,"Clearing the Screen")
tn:send_clear()
tn:get_all_data()
tn:get_screen_debug(2)
count = count + 1
end
if count == 5 then
return false, 'Could not get to CICS after 5 attempts. Is this even CICS?'
end
stdnse.debug(2,"Sending 'CESL'")
tn:send_cursor('CESL')
tn:get_all_data()
if tn:isClear() then
tn:get_all_data(1000)
end
tn:get_screen_debug(2)
if tn:find("Signon to CICS") then
stdnse.verbose(2,"At CICS Login Transaction (CESL)")
tn:disconnect()
return true
end
tn:disconnect()
return false, 'Could not get to CESL (CICS Logon Screen)'
end
-- Filter iterator for unpwdb
-- IDs are limited to 8 alpha numeric and @, #, $ and can't start with a number
-- pattern:
-- ^%D = The first char must NOT be a digit
-- [%w@#%$] = All letters including the special chars @, #, and $.
local valid_name = function(x)
if nmap.registry.tsoinvalid and nmap.registry.tsoinvalid[x] then
return false
end
return (string.len(x) <= 8 and string.match(x,"^%D+[%w@#%$]"))
end
-- Checks string to see if it follows valid password limitations
local valid_pass = function(x)
return (string.len(x) <= 8 )
end
action = function(host, port)
local commands = stdnse.get_script_args(SCRIPT_NAME .. '.commands') or "cics"
local cicstst, err = cics_test(host, port, commands)
if cicstst then
local options = { key1 = commands }
local engine = brute.Engine:new(Driver, host, port, options)
stdnse.debug(2,"Starting CICS Brute Forcing")
engine:setUsernameIterator(unpwdb.filter_iterator(brute.usernames_iterator(),valid_name))
engine:setPasswordIterator(unpwdb.filter_iterator(brute.passwords_iterator(),valid_pass))
engine.options.script_name = SCRIPT_NAME
engine.options:setTitle("CICS User Accounts")
local status, result = engine:start()
return result
else
return err
end
end