75 lines
2.2 KiB
Lua
75 lines
2.2 KiB
Lua
local nmap = require "nmap"
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local string = require "string"
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-- NSE x11-access v1.3
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description = [[
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Checks if you're allowed to connect to the X server.
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If the X server is listening on TCP port 6000+n (where n is the display
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number), it is possible to check if you're able to get connected to the
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remote display by sending a X11 initial connection request.
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In reply, the success byte (0x00 or 0x01) will determine if you are in
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the <code>xhost +</code> list. In this case, script will display the message:
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<code>X server access is granted</code>.
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]]
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---
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-- @output
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-- Host script results:
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-- |_ x11-access: X server access is granted
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--
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-- @xmloutput
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-- true
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author = "vladz"
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license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
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categories = {"default", "safe", "auth"}
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portrule = function(host, port)
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return ((port.number >= 6000 and port.number <= 6009)
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or (port.service and string.match(port.service, "^X11")))
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-- If port.version.product is not equal to nil, version
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-- detection "-sV" has already done this X server test.
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and port.version.product == nil
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end
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action = function(host, port)
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local result, socket, try, catch
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socket = nmap.new_socket()
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catch = function()
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socket:close()
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end
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try = nmap.new_try(catch)
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try(socket:connect(host, port))
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-- Sending the network dump of a x11 connection request (captured
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-- from the XOpenDisplay() function):
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--
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-- 0x6c 0x00 0x0b 0x00 0x00 0x00 0x00
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-- 0x00 0x00 0x00 0x00 0x00 0x00
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try(socket:send("\108\000\011\000\000\000\000\000\000\000\000\000"))
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-- According to the XOpenDisplay() sources, server answer is
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-- stored in a xConnSetupPrefix structure [1]. The function
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-- returns NULL if it does not succeed, and more precisely: When
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-- the success field of this structure (stored on 1 byte) is not
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-- equal to xTrue [2]. For more information, see the Xlib
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-- programming Manual [3].
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--
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-- [1] xConnSetupPrefix structure is defined in X11/Xproto.h.
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-- [2] xTrue = 0x01 according to X11/Xproto.h.
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-- [3] http://www.sbin.org/doc/Xlib
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result = try(socket:receive_bytes(1))
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socket:close()
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-- Check if first byte received is 0x01 (xTrue: succeed).
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if string.match(result, "^\001") then
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return true, "X server access is granted"
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end
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end
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