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Clean up a lot of the http-enum.nse code; add some comments; abstract the 'is this a 404?' logic into a function (so it can eventually used by other scripts

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ron
2009-08-22 23:54:27 +00:00
parent c9a62acf31
commit a546ebc84f
1 changed files with 112 additions and 68 deletions
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180
scripts/http-enum.nse
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@@ -74,6 +74,11 @@ portrule = function(host, port)
return true
end
---Take the data returned from a HTTP request and return the status string. Useful
-- for <code>print_debug</code> messaes and even for advanced output.
--
--@param data The data returned by a HTTP request (can be nil or empty)
--@return The status string, the status code, or "<unknown status>".
local function get_status_string(data)
-- Make sure we have valid data
if(data == nil) then
@@ -95,7 +100,14 @@ local function get_status_string(data)
end
end
local function add_from_files(entries)
---Get the list of fingerprints from files. The files are defined in <code>fingerprint_files</code>.
--
-- TODO: It may be a good idea, in the future, to cache them. Otherwise, these files are re-read for every
-- host that's scanned. That can be quite a bit of i/o.
--
--@return An array of entries, each of which have a <code>checkdir</code> field, and possibly a <code>checkdesc</code>.
local function get_fingerprints()
local entries = {}
local PREAUTH = "# Pre-Auth"
local POSTAUTH = "# Post-Auth"
@@ -110,7 +122,7 @@ local function add_from_files(entries)
else
stdnse.print_debug(1, "http-enum: Attempting to parse fingerprint file %s", filename)
local product = ""
local product = nil
for line in io.lines(filename) do
-- Ignore "Pre-Auth", "Post-Auth", and blank lines
if(string.sub(line, 1, #PREAUTH) ~= PREAUTH and string.sub(line, 1, #POSTAUTH) ~= POSTAUTH and #line > 0) then
@@ -135,10 +147,20 @@ end
-- 200, and doesn't return data. We implement the check like this because can't always rely on OPTIONS to
-- tell the truth.
--
--Note: If <code>identify_404</code> returns a 200 status, HEAD requests should be disabled.
--
--@param host The host object.
--@param port The port to use -- note that SSL will automatically be used, if necessary.
--@param result_404 [optional] The result when an unknown page is requested. This is returned by <code>identify_404</code>.
-- If the 404 page returns a '200' code, then we disable HEAD requests.
--@return A boolean value: true if HEAD is usable, false otherwise.
local function check_head(host, port)
local function can_use_head(host, port, result_404)
-- If the 404 result is 200, don't use HEAD.
if(result_404 == 200) then
return false
end
-- Perform a HEAD request and see what happens.
local data = http.head( host, port, '/' )
if data then
if data.status and data.status == 302 and data.header and data.header.location then
@@ -165,13 +187,16 @@ local function check_head(host, port)
return false
end
---Determine whether or not we can actually scan the server (if a 301 is returned, that's bad).
---Request the root folder, "/", in order to determine if we can use a GET request against this server. If the server returns
-- 301 Moved Permanently or 401 Authentication Required, then tests against this server will most likely fail.
--
-- TODO: It's probably worthwhile adding a script-arg that will ignore the output of this function and always scan servers.
--
--@param host The host object.
--@param port The port to use -- note that SSL will automatically be used, if necessary.
--@return (result, message) result is a boolean: true means we're good to go, false means there's an error.
-- The error is returned in message.
local function check_get(host, port)
local function can_use_get(host, port)
stdnse.print_debug(1, "Checking if a GET request is going to work out")
-- Try getting the root directory
@@ -248,14 +273,13 @@ local function clean_404(body)
return openssl.md5(body)
end
--io.write(body .. "\n\n")
return body
end
---Try requesting a non-existent file to determine how the server responds to unknown pages ("404 pages"). If the server
-- responds with a 404 status code, as it is supposed to, then this function simply returns 404. If it contains one
-- of a series of common error codes, including unauthorized, moved, and others, it is returned like a 404.
---Try requesting a non-existent file to determine how the server responds to unknown pages ("404 pages"), which a)
-- tells us what to expect when a non-existent page is requested, and b) tells us if the server will be impossible to
-- scan. If the server responds with a 404 status code, as it is supposed to, then this function simply returns 404. If it
-- contains one of a series of common status codes, including unauthorized, moved, and others, it is returned like a 404.
--
-- If, however, the 404 page returns a 200 status code, it gets interesting. First, it attempts to clean the returned
-- body (see <code>clean_404</code> for details). Once any dynamic-looking data has been removed from the string, another
@@ -273,7 +297,7 @@ local function identify_404(host, port)
data = http.get(host, port, URL_404)
if(data == nil) then
stdnse.print_debug(1, "http-enum.nse: Failed while testing for 404 error message")
stdnse.print_debug(1, "http-enum.nse: Failed while testing for 404 status code")
return false, "Failed while testing for 404 error message"
end
@@ -333,29 +357,65 @@ local function identify_404(host, port)
return false, string.format("Unexpected response returned for 404 check: %s", get_status_string(data))
end
action = function(host, port)
---Determine whether or not the page that was returned is a 404 page. This is actually a pretty simple function,
-- but it's best to keep this logic close to <code>identify_404</code>, since they will generally be used
-- together.
--
--@param data The data returned by the HTTP request
--@param result_404 The status code to expect for non-existent pages. This is returned by <code>identify_404</code>.
--@param known_404 The 404 page itself, if <code>result_404</code> is 200. If <code>result_404</code> is something
-- else, this parameter is ignored and can be set to <code>nil</code>. This is returned by
-- <code>identfy_404</code>.
local function page_exists(data, result_404, known_404)
if(data and data.status) then
-- Handle the most complicated case first: the "200 Ok" response
if(data.status == 200) then
if(result_404 == 200) then
-- If the 404 response is also "200", deal with it (check if the body matches)
if(clean_404(data.body) ~= known_404) then
stdnse.print_debug(1, "http-enum.nse: Page returned a body that doesn't match known 404 body, it exists")
return true
else
return false
end
else
-- If 404s return something other than 200, and we got a 200, we're good to go
stdnse.print_debug(1, "http-enum.nse: Page was '%s', it exists!", get_status_string(data))
return true
end
else
-- If the result isn't a 200, check if it's a 404 or returns the same code as a 404 returned
if(data.status ~= 404 and data.status ~= result_404) then
-- If this check succeeded, then the page isn't a standard 404 -- it could be a redirect, authentication request, etc. Unless the user
-- asks for everything (with a script argument), only display 401 Authentication Required here.
stdnse.print_debug(1, "http-enum.nse: Page didn't match the 404 response (%s)", get_status_string(data))
local safeURLcheck = { }
if(data.status == 401) then -- "Authentication Required"
return true
else
if(nmap.registry.args.displayall == '1' or nmap.registry.args.displayall == "true") then
return true
end
end
return false
else
-- Page was a 404, or looked like a 404
return false
end
end
else
stdnse.print_debug(1, "http-enum.nse: HTTP request failed (is the host still up?)")
return false
end
end
action = function(host, port)
local response = " \n"
-- Add URLs from external files
safeURLcheck = add_from_files(safeURLcheck)
-- Check if we can use HEAD requests
local use_head = check_head(host, port)
-- If we can't use HEAD, make sure we can use GET requests
if(use_head == false) then
local result, err = check_get(host, port)
if(result == false) then
if(nmap.debugging() > 0) then
return "ERROR: " .. err
else
return nil
end
end
end
local URLs = get_fingerprints()
-- Check what response we get for a 404
local result, result_404, known_404 = identify_404(host, port)
@@ -367,30 +427,40 @@ action = function(host, port)
end
end
-- need to be able to check body if returned
if(known_404 ~= nil) then
use_head = false
-- Check if we can use HEAD requests
local use_head = can_use_head(host, port, result_404)
-- If we can't use HEAD, make sure we can use GET requests
if(use_head == false) then
local result, err = can_use_get(host, port)
if(result == false) then
if(nmap.debugging() > 0) then
return "ERROR: " .. err
else
return nil
end
end
end
-- Queue up the checks
local all = {}
local i
for i = 1, #safeURLcheck, 1 do
for i = 1, #URLs, 1 do
if(nmap.registry.args.limit and i > tonumber(nmap.registry.args.limit)) then
stdnse.print_debug(1, "http-enum.nse: Reached the limit (%d), stopping", nmap.registry.args.limit)
break;
end
if(use_head) then
all = http.pHead(host, port, safeURLcheck[i].checkdir, nil, nil, all)
all = http.pHead(host, port, URLs[i].checkdir, nil, nil, all)
else
all = http.pGet(host, port, safeURLcheck[i].checkdir, nil, nil, all)
all = http.pGet(host, port, URLs[i].checkdir, nil, nil, all)
end
end
local results = http.pipeline(host, port, all, nil)
-- check for http.pipeline error
-- Check for http.pipeline error
if(results == nil) then
stdnse.print_debug(1, "http-enum.nse: http.pipeline returned nil")
if(nmap.debugging() > 0) then
@@ -401,40 +471,14 @@ action = function(host, port)
end
for i, data in pairs(results) do
if(data and data.status) then
-- Handle the most complicated case first: the "200 Ok" response
if(data.status == 200) then
-- If the 404 response is also "200", deal with it
if(result_404 == 200) then
if(clean_404(data.body) ~= known_404) then
stdnse.print_debug(1, "http-enum.nse: Page returned that doesn't match the 404 body (%s: %s)", safeURLcheck[i].checkdir, safeURLcheck[i].checkdesc)
response = response .. safeURLcheck[i].checkdir .. " " .. safeURLcheck[i].checkdesc .. "\n"
end
else
-- If 404s return something other than 200, and we got a 200, we're good to go
stdnse.print_debug(1, "http-enum.nse: Page was '%s' (%s: %s)", get_status_string(data), safeURLcheck[i].checkdir, safeURLcheck[i].checkdesc)
response = response .. safeURLcheck[i].checkdir .. " " .. safeURLcheck[i].checkdesc .. "\n"
end
if(page_exists(data, result_404, known_404)) then
if(URLs[i].checkdesc) then
stdnse.print_debug(1, "http-enum.nse: Found a valid page! (%s: %s)", URLs[i].checkdir, URLs[i].checkdesc)
response = response .. URLs[i].checkdir .. " " .. URLs[i].checkdesc .. "\n"
else
-- If the response isn't a 200, check it against what we expect a 404 to be
if(data.status ~= result_404 and data.status ~= 404) then
-- If this check succeeded, then the page isn't a standard 404 -- it could be a redirect, authentication request, etc. Unless the user
-- asks for everything (with a script argument), only display 401 Authentication Required here.
stdnse.print_debug(1, "http-enum.nse: Page didn't match the 404 response (%s: %s [%s])", safeURLcheck[i].checkdir, safeURLcheck[i].checkdesc, get_status_string(data))
if(data.status == 401) then -- "Authentication Required"
response = response .. safeURLcheck[i].checkdir .. " " .. safeURLcheck[i].checkdesc .. " (" .. get_status_string(data) .. ")\n"
else
--
if(nmap.registry.args.displayall == '1' or nmap.registry.args.displayall == "true") then
response = response .. safeURLcheck[i].checkdir .. " " .. safeURLcheck[i].checkdesc .. " (" .. get_status_string(data) .. ")\n"
end
end
end
stdnse.print_debug(1, "http-enum.nse: Found a valid page! (%s: %s)", URLs[i].checkdir, URLs[i].checkdesc)
response = response .. URLs[i].checkdir .. "\n"
end
else
stdnse.print_debug(1, "http-enum.nse: HTTP request failed to return either a status or data")
end
end