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local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"
local string = require "string"
local ftp = require "ftp"
description=[[
Checks to see if an FTP server allows port scanning using the FTP bounce method.
]]
author = "Marek Majkowski"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
---
-- @args ftp-bounce.username Username to log in with. Default
-- <code>anonymous</code>.
-- @args ftp-bounce.password Password to log in with. Default
-- <code>IEUser@</code>.
-- @args ftp-bounce.checkhost Host to try connecting to with the PORT command.
-- Default: scanme.nmap.org
--
-- @output
-- PORT STATE SERVICE
-- 21/tcp open ftp
-- |_ftp-bounce: bounce working!
--
-- PORT STATE SERVICE
-- 21/tcp open ftp
-- |_ftp-bounce: server forbids bouncing to low ports <1025
categories = {"default", "safe"}
portrule = shortport.port_or_service({21, 990}, {"ftp", "ftps"})
local function get_portfmt()
local arghost = stdnse.get_script_args(SCRIPT_NAME .. ".checkhost") or "scanme.nmap.org"
local reg = nmap.registry[SCRIPT_NAME] or {}
local addr = reg[arghost]
if not addr then
local status, addrs = nmap.resolve(arghost, "inet")
if not status or #addrs < 1 then
stdnse.verbose1("Couldn't resolve %s, scanning 10.0.0.1 instead.", arghost)
addr = "10.0.0.1"
else
addr = addrs[1]
end
reg[arghost] = addr
end
nmap.registry[SCRIPT_NAME] = reg
return string.format("PORT %s,%%s\r\n", (string.gsub(addr, "%.", ",")))
end
action = function(host, port)
local user = stdnse.get_script_args(SCRIPT_NAME .. ".username") or "anonymous"
local pass = stdnse.get_script_args(SCRIPT_NAME .. ".password") or "IEUser@"
-- BANNER
local socket, code, message, buffer = ftp.connect(host, port, {request_timeout=10000})
if not socket then
return nil
end
if code < 200 or code > 299 then
socket:close()
return nil
end
socket:set_timeout(5000)
-- USER
local status, code, message = ftp.auth(socket, buffer, user, pass)
if not status then
stdnse.debug1("Authentication rejected: %s %s", code or "socket", message)
ftp.close(socket)
return nil
end
-- PORT highport
local portfmt = get_portfmt()
-- This is actually port 256*80 + 80 = 20560
if not socket:send(string.format(portfmt, "80,80")) then
stdnse.debug1("Can't send PORT")
return nil
end
code, message = ftp.read_reply(buffer)
if not code then
stdnse.debug1("Error after PORT: %s", message)
return nil
end
if code < 200 or code > 299 then
stdnse.verbose1("PORT response: %d %s", code, message)
ftp.close(socket)
-- return "server forbids bouncing"
return nil
end
-- PORT lowport
if not socket:send(string.format(portfmt, "0,80")) then
stdnse.debug1("Can't send PORT")
return nil
end
code, message = ftp.read_reply(buffer)
if not code then
stdnse.debug1("Error after PORT: %s", message)
return nil
end
if code < 200 or code > 299 then
stdnse.verbose1("PORT (low port) response: %d %s", code, message)
ftp.close(socket)
return "server forbids bouncing to low ports <1025"
end
ftp.close(socket)
return "bounce working!"
end
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