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Diffstat (limited to '')
| -rw-r--r-- | scripts/banner.nse | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/scripts/banner.nse b/scripts/banner.nse new file mode 100644 index 0000000..1482d16 --- /dev/null +++ b/scripts/banner.nse @@ -0,0 +1,198 @@ +local comm = require "comm" +local nmap = require "nmap" +local stdnse = require "stdnse" +local shortport = require "shortport" +local table = require "table" +local U = require "lpeg-utility" + +description = [[ +A simple banner grabber which connects to an open TCP port and prints out anything sent by the listening service within five seconds. + +The banner will be truncated to fit into a single line, but an extra line may be printed for every +increase in the level of verbosity requested on the command line. +]] + +--- +-- @output +-- 21/tcp open ftp +-- |_ banner: 220 FTP version 1.0\x0D\x0A +-- @arg banner.ports Which ports to grab. Same syntax as -p option. Use +-- "common" to only grab common text-protocol banners. +-- Default: all ports. +-- @arg banner.timeout How long to wait for a banner. Default: 5s + + +author = "jah" +license = "Same as Nmap--See https://nmap.org/book/man-legal.html" +categories = {"discovery", "safe"} + + + +local portarg = stdnse.get_script_args(SCRIPT_NAME .. ".ports") +if portarg then + if portarg == "common" then + portarg = "13,17,21-23,25,129,194,587,990,992,994,6667,6697" + end + -- ensure TCP + portarg = portarg:gsub("^[T:]*", "T:") + portrule = shortport.port_range(portarg) +else + portrule = function(host, port) return port.protocol == "tcp" end +end + + +--- +-- Grabs a banner and outputs it nicely formatted. +action = function( host, port ) + + local out = grab_banner(host, port) + return output( out ) + +end + + + +--- +-- Connects to the target on the given port and returns any data issued by a listening service. +-- @param host Host Table. +-- @param port Port Table. +-- @return String or nil if data was not received. +function grab_banner(host, port) + -- Did the service engine already do the hard work? + if port.version and port.version.service_fp then + local response = U.get_response(port.version.service_fp, "NULL") + if response then + return response:match("^%s*(.-)%s*$"); + end + end + + local opts = {} + opts.timeout = stdnse.parse_timespec(stdnse.get_script_args(SCRIPT_NAME .. ".timeout")) + opts.timeout = (opts.timeout or 5) * 1000 + + local status, response = comm.get_banner(host, port, opts) + + if not status then + local errlvl = { ["EOF"]=3,["TIMEOUT"]=3,["ERROR"]=2 } + stdnse.debug(errlvl[response] or 1, "failed for %s on %s port %s. Message: %s", host.ip, port.protocol, port.number, response or "No Message.") + return nil + end + + return response:match("^%s*(.-)%s*$"); + +end + + +--- +-- Formats the banner for printing to the port script result. +-- +-- Non-printable characters are hex encoded and the banner is +-- then truncated to fit into the number of lines of output desired. +-- @param out String banner issued by a listening service. +-- @return String formatted for output. +function output( out ) + + if type(out) ~= "string" or out == "" then return nil end + + local filename = SCRIPT_NAME + local line_len = 75 -- The character width of command/shell prompt window. + local fline_offset = 5 -- number of chars excluding script id not available to the script on the first line + + -- number of chars available on the first line of output + -- we'll skip the first line of output if the filename is looong + local fline_len + if filename:len() < (line_len-fline_offset) then + fline_len = line_len -1 -filename:len() -fline_offset + else + fline_len = 0 + end + + -- number of chars allowed on subsequent lines + local sline_len = line_len -1 -(fline_offset-2) + + -- total number of chars allowed for output (based on verbosity) + local total_out_chars + if fline_len > 0 then + total_out_chars = fline_len + (extra_output()*sline_len) + else + -- skipped the first line so we'll have an extra lines worth of chars + total_out_chars = (1+extra_output())*sline_len + end + + -- replace non-printable ascii chars - no need to do the whole string + out = replace_nonprint(out, 1+total_out_chars) -- 1 extra char so we can truncate below. + + -- truncate banner to total_out_chars ensuring we remove whole hex encoded chars + if out:len() > total_out_chars then + while out:len() > total_out_chars do + if (out:sub(-4,-1)):match("\\x%x%x") then + out = out:sub(1,-1-4) + else + out = out:sub(1,-1-1) + end + end + out = ("%s..."):format(out:sub(1,total_out_chars-3)) -- -3 for ellipsis + end + + -- break into lines - this will look awful if line_len is more than the actual space available on a line... + local ptr = fline_len + local t = {} + while true do + if out:len() >= ptr then + t[#t+1] = (ptr > 0 and out:sub(1,ptr)) or " " -- single space if we skipped the first line + out = out:sub(ptr+1,-1) + ptr = sline_len + else + t[#t+1] = out + break + end + end + + return table.concat(t,"\n") + +end + + + +--- +-- Replaces characters with ASCII values outside of the range of standard printable +-- characters (decimal 32 to 126 inclusive) with hex encoded equivalents. +-- +-- The second parameter dictates the number of characters to return, however, if the +-- last character before the number is reached is one that needs replacing then up to +-- three characters more than this number may be returned. +-- If the second parameter is nil, no limit is applied to the number of characters +-- that may be returned. +-- @param s String on which to perform substitutions. +-- @param len Number of characters to return. +-- @return String. +function replace_nonprint( s, len ) + + local t = {} + local count = 0 + + for c in s:gmatch(".") do + if c:byte() < 32 or c:byte() > 126 then + t[#t+1] = ("\\x%s"):format( ("0%s"):format( ( (stdnse.tohex( c:byte() )):upper() ) ):sub(-2,-1) ) -- capiche + count = count+4 + else + t[#t+1] = c + count = count+1 + end + if type(len) == "number" and count >= len then break end + end + + return table.concat(t) + +end + + + +--- +-- Returns a number for each level of verbosity specified on the command line. +-- +-- Ignores level increases resulting from debugging level. +-- @return Number +function extra_output() + return (nmap.verbosity()-nmap.debugging()>0 and nmap.verbosity()-nmap.debugging()) or 0 +end |