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Re: [NSE Script] MySQL Server Information
From: Kris Katterjohn <katterjohn () gmail com>
Date: Tue, 18 Dec 2007 00:22:46 -0600

jah wrote:
No, it seems your script was not the cause, my messing around caused it. I think "many connection errors" refers to the application layer [1] and after much testing, I found that your script is closing sockets without issue and that the issue was further into the script. Then after a bit of reading, I found that the script was breaking when the mysql server responded with an error which it does by serving 0xff instead of a protocol byte, followed by a two byte error code and then the error string [2]. It was evident that your code wasn't handling this even though I couldn't tell exactly where it broke. Doesn't really matter though...

I've attached your script, slightly modified to return any mysql error details and which shouldn't cause the above described issue in these circumstances. Hopefully.

While I was testing it with many many random hosts I found that, using version detection, the version always contains "unauthorized" when I get an error code 0x046A (1130 ~ "Host not allowed to connect") from the script output - quite useful cross check I thought - and, given that nmap will have already matched the mysql error, it's maybe worth testing for this straight away (if used with version detection) to avoid running the script. I've included this modded portrule too, but it's not implemented so you can have a play - I imagine the script needs a bit more testing anyway. Next step, supply the script with args for user:pwd and try to return database names...


Great job, man :)

I've attached yet another modified script which I'd like for you to try out if you can.

The changes are pretty obvious I think, but here's the rundown:

Added some comments to the top.

I used a little more object-oriented approach in the portrule involving the extrainfo field, especially since I added another match against it.

I grepped the nmap-service-probes and saw "unauthorized" with a lowercase and uppercase U, so I edited that part. I saw no occurrences of your suggested "unauthorised" in there, so I didn't add that.

I added a check for too many connections, which I saw in the probes file. It should match the different little versions of it from there, though I didn't find a server with that error to test with.

Another change was just for personal preference :) Instead of indenting the rest of the script after the protocol vs. error check, I just return from that if() and the rest was as before. I just think it's too long to warrant the extra indentation.

jah


Thanks a lot,
Kris Katterjohn
-- Connect to MySQL server and print information such as the protocol and
-- version numbers, thread id, status, capabilities and the password salt

-- If, after service detection, the MySQL server appears to be blocking
-- our host or is blocked from too many connections, then we don't bother
-- running this script.

-- Many thanks to jah (jah () zadkiel plus com) for testing and enhancements

id = "MySQL Server Information"

description = "Connects to a MySQL server and prints information"

author = "Kris Katterjohn <katterjohn () gmail com>"

license = "Look at Nmap's COPYING"

categories = { "discovery", "safe" }

require 'shortport'
require 'bit'

-- Grabs NUL-terminated string
local getstring = function(orig)
        local str = ""
        local index = 1

        while orig:byte(index) ~= 0 do
                str = str .. string.char(orig:byte(index))

                index = index + 1
        end

        return str
end

-- Convert two bytes into a number
ntohs = function(num)
        local b1 = bit.band(num:byte(1), 255)
        local b2 = bit.band(num:byte(2), 255)

        return bit.bor(b1, bit.lshift(b2, 8))
end

-- Convert three bytes into a number
ntoh3 = function(num)
        local b1 = bit.band(num:byte(1), 255)
        local b2 = bit.band(num:byte(2), 255)
        local b3 = bit.band(num:byte(3), 255)

        return bit.bor(b1, bit.lshift(b2, 8), bit.lshift(b3, 16))
end

-- Convert four bytes into a number
ntohl = function(num)
        local b1 = bit.band(num:byte(1), 255)
        local b2 = bit.band(num:byte(2), 255)
        local b3 = bit.band(num:byte(3), 255)
        local b4 = bit.band(num:byte(4), 255)

        return bit.bor(b1, bit.lshift(b2, 8), bit.lshift(b3, 16), bit.lshift(b4, 24))
end

-- Convert number to a list of capabilities for printing
capabilities = function(num)
        local caps = ""

        if bit.band(num, 1) > 0 then
                caps = caps .. "Long Passwords, "
        end

        if bit.band(num, 8) > 0 then
                caps = caps .. "Connect with DB, "
        end

        if bit.band(num, 32) > 0 then
                caps = caps .. "Compress, "
        end

        if bit.band(num, 64) > 0 then
                caps = caps .. "ODBC, "
        end

        if bit.band(num, 2048) > 0 then
                caps = caps .. "SSL, "
        end

        if bit.band(num, 8192) > 0 then
                caps = caps .. "Transactions, "
        end

        if bit.band(num, 32768) > 0 then
                caps = caps .. "Secure Connection, "
        end

        return caps:gsub(", $", "")
end

portrule = function(host, port)
        local extra = port.version.extrainfo

        if
                (port.number == 3306
                or port.service == "mysql")
                and port.protocol == "tcp"
                and port.state == "open"
                and not (extra ~= nil
                        and (extra:match("[Uu]nauthorized")
                                or extra:match("[Tt]oo many connection")))
        then
                return true
        end

        return false
end

action = function(host, port)
        local sock
        local response = ""
        local output = ""

        sock = nmap.new_socket()

        sock:set_timeout(5000)

        sock:connect(host.ip, port.number)

        while true do
                local status, line = sock:receive_lines(1)

                if not status then
                        break
                end

                response = response .. line
        end

        sock:close()

        local length = ntoh3(response:sub(1, 3))

        if length ~= response:len() - 4 then
                return "Invalid greeting (Not MySQL?)"
        end

        -- Keeps track of where we are in the binary data
        local offset = 1 + 4

        local protocol = response:byte(offset)

        if (protocol == 255) then
                output = "MySQL Error detected!" -- 0xff found where protocol should be
                
                offset = offset + 1
                
                local sqlerrno = ntohs(response:sub(offset, offset + 2))
                
                offset = offset + 2
                
                local sqlerrstr = response:sub(offset)
                
                output = output .. "\n" .. "Error Code was: " .. sqlerrno .. "\n"
                
                output = output .. "\n" .. sqlerrstr

                return output
        end

        offset = offset + 1

        local version = getstring(response:sub(offset))

        offset = offset + version:len() + 1

        local threadid = ntohl(response:sub(offset, offset + 4))

        offset = offset + 4

        local salt = getstring(response:sub(offset))

        offset = offset + salt:len() + 1

        local caps = capabilities(ntohs(response:sub(offset, offset + 2)))

        offset = offset + 2

        offset = offset + 1

        local status = ""

        if ntohs(response:sub(offset, offset + 2)) == 2 then
                status = "Autocommit"
        end

        offset = offset + 2

        offset = offset + 13 -- unused

        if response:len() - offset + 1 == 13 then
                salt = salt .. getstring(response:sub(offset))
        end

        output = output .. "Protocol: " .. protocol .. "\n"
        output = output .. "Version: " .. version .. "\n"
        output = output .. "Thread ID: " .. threadid .. "\n"

        if caps:len() > 0 then
                output = output .. "Some Capabilities: " .. caps .. "\n"
        end

        if status:len() > 0 then
                output = output .. "Status: " .. status .. "\n"
        end

        output = output .. "Salt: " .. salt .. "\n"

        return output
end


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