Check for non-200 responses that may indicate url is present.

scripts/rtsp-url-brute.nse

@@ -8,6 +8,11 @@ local table = require "table"
 
 description = [[
 Attempts to enumerate RTSP media URLS by testing for common paths on devices such as surveillance IP cameras.
+
+The script attempts to discover valid RTSP URLs by sending a DESCRIBE
+request for each URL in the dictionary. It then parses the response, based
+on which it determines whether the URL is valid or not.
+
 ]]
 
 ---
@@ -18,12 +23,20 @@ Attempts to enumerate RTSP media URLS by testing for common paths on devices suc
 -- PORT    STATE SERVICE
 -- 554/tcp open  rtsp
 -- | rtsp-url-brute:
--- |   Discovered URLs
--- |_    rtsp://camera.example.com/mpeg4
---
--- The script attempts to discover valid RTSP URLs by sending a DESCRIBE
--- request for each URL in the dictionary. It then parses the response, based
--- on which it determines whether the URL is valid or not.
+-- |   discovered:
+-- |     rtsp://camera.example.com/mpeg4
+-- |   other responses:
+-- |     401:
+-- |_      rtsp://camera.example.com/live/mpeg4
+-- @xmloutput
+-- <table key="discovered">
+--   <elem>rtsp://camera.example.com/mpeg4</elem>
+-- </table>
+-- <table key="other responses">
+--   <table key="401">
+--     <elem>rtsp://camera.example.com/live/mpeg4</elem>
+--   </table>
+-- </table>
 --
 -- @args rtsp-url-brute.urlfile sets an alternate URL dictionary file
 -- @args rtsp-url-brute.threads sets the maximum number of parallel threads to run
@@ -57,6 +70,26 @@ urlIterator = function(fd)
   return coroutine.wrap( getNextUrl )
 end
 
+local function fetch_url(host, port, url)
+  local helper = rtsp.Helper:new(host, port)
+  local status = helper:connect()
+
+  if not status then
+    stdnse.debug2("ERROR: Connecting to RTSP server url: %s", url)
+    return nil
+  end
+
+  local response
+  status, response = helper:describe(url)
+  if not status then
+    stdnse.debug2("ERROR: Sending DESCRIBE request to url: %s", url)
+    return nil, response
+  end
+
+  helper:close()
+  return true, response
+end
+
 -- Fetches the next url from the iterator, creates an absolute url and tries
 -- to fetch it from the RTSP service.
 -- @param host table containing the host table as received by action
@@ -65,30 +98,16 @@ end
 -- @param result table containing the urls that were successfully retrieved
 local function processURL(host, port, url_iter, result)
   local condvar = nmap.condvar(result)
+  local name = stdnse.get_hostname(host)
   for u in url_iter do
-    local name = ( host.targetname and #host.targetname > 0 ) and host.targetname or
-      ( host.name and #host.name > 0 ) and host.name or
-      host.ip
     local url = ("rtsp://%s%s"):format(name, u)
-    local helper = rtsp.Helper:new(host, port)
-    local status = helper:connect()
-
-    if ( not(status) ) then
-      stdnse.debug2("ERROR: Connecting to RTSP server url: %s", url)
+    local status, response = fetch_url(host, port, url)
+    if not status then
       table.insert(result, { url = url, status = -1 } )
       break
+    else
+      table.insert(result, { url = url, status = response.status } )
     end
-
-    local response
-    status, response = helper:describe(url)
-    if ( not(status) ) then
-      stdnse.debug2("ERROR: Sending DESCRIBE request to url: %s", url)
-      table.insert(result, { url = url, status = -1 } )
-      break
-    end
-
-    table.insert(result, { url = url, status = response.status } )
-    helper:close()
   end
   condvar "signal"
 end
@@ -118,6 +137,16 @@ action = function(host, port)
     return stdnse.format_output(false, ("Could not open the URL dictionary: %s"):format(f))
   end
 
+  -- Try to see what a nonexistent URL looks like
+  local status, response = fetch_url(
+    host, port, ("rtsp://%s/%s"):format(
+      stdnse.get_hostname(host), stdnse.generate_random_string(14))
+    )
+  local status_404 = 404
+  if status then
+    local status_404 = response.status
+  end
+
   local threads = {}
   for t=1, threadcount do
     local co = stdnse.new_thread(processURL, host, port, url_iter, result)
@@ -135,30 +164,38 @@ action = function(host, port)
 
   -- urls that could not be retrieved due to low level errors, such as
   -- failure in socket send or receive
-  local failure_urls = { name='An error occurred while testing the following URLs' }
+  local failure_urls = {}
 
   -- urls that elicited a 200 OK response
-  local success_urls = { name='Discovered URLs' }
+  local success_urls = {}
 
-  -- urls requiring authentication
-  -- local auth_urls = { name='URL requiring authentication' }
+  -- urls that got some non-404-type response
+  local urls_by_code = {}
 
   for _, r in ipairs(result) do
     if ( r.status == -1 ) then
       table.insert(failure_urls, r.url)
     elseif ( r.status == 200 ) then
       table.insert(success_urls, r.url)
-      -- elseif ( r.status == 401 ) then
-      --   table.insert(auth_urls, r.url )
+    elseif r.status ~= status_404 then
+      local s = tostring(r.status)
+      urls_by_code[s] = urls_by_code[s] or {}
+      table.insert(urls_by_code[s], r.url)
     end
   end
 
-  local result = { success_urls, failure_urls }
-
-  -- insert our URLs requiring auth ONLY if not ALL urls returned auth
-  --if (#result > #auth_urls) then
-  --  table.insert(result, 2, auth_urls)
-  --end
+  local output = stdnse.output_table()
+  if next(failure_urls) then
+    output.errors = failure_urls
+  end
+  if next(success_urls) then
+    output.discovered = success_urls
+  end
+  if next(urls_by_code) then
+    output["other responses"] = urls_by_code
+  end
 
-  return stdnse.format_output(true, result )
+  if #output > 0 then
+    return output
+  end
 end