Nmap http-form-brute NSE Script


This page contains detailed information about how to use the http-form-brute NSE script. For list of all NSE scripts, visit the Nmap NSE Library.

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Overview
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Script Overview

Script source code: https://github.com/nmap/nmap/tree/master/scripts/http-form-brute.nse
Script categories: intrusive, brute
Target service / protocol: http, https
Target network port(s): 80, 443
List of CVEs: -

Script Description

The http-form-brute.nse script performs brute force password auditing against http form-based authentication.

This script uses the unpwdb and brute libraries to perform password guessing. Any successful guesses are stored in the nmap registry, using the creds library, for other scripts to use.

The script automatically attempts to discover the form method, action, and field names to use in order to perform password guessing. (Use argument path to specify the page where the form resides.) If it fails doing so the form components can be supplied using arguments method, path, uservar, and passvar. The same arguments can be used to selectively override the detection outcome.

The script contains a small database of known web apps' form information. This improves form detection and also allows for form mangling and custom success detection functions. If the script arguments aren't expressive enough, users are encouraged to edit the database to fit.

After attempting to authenticate using a HTTP GET or POST request the script analyzes the response and attempts to determine whether authentication was successful or not. The script analyzes this by checking the response using the following rules:

  1. If the response was empty the authentication was successful.
  2. If the onsuccess argument was provided then the authentication either succeeded or failed depending on whether the response body contained the message/pattern passed in the onsuccess argument.
  3. If no onsuccess argument was passed, and if the onfailure argument was provided then the authentication either succeeded or failed depending on whether the response body does not contain the message/pattern passed in the onfailure argument.
  4. If neither the onsuccess nor onfailure argument was passed and the response contains a form field named the same as the submitted password parameter then the authentication failed.
  5. Authentication was successful.

Http-form-brute NSE Script Arguments

This is a full list of arguments supported by the http-form-brute.nse script:

http-form-brute.hostname

Sets the host header in case of virtual hosting

http-form-brute.method

Sets the HTTP method (default: "POST")

http-form-brute.onfailure

(optional) sets the message/pattern to expect on unsuccessful authentication

http-form-brute.onsuccess

(optional) sets the message/pattern to expect on successful authentication

http-form-brute.passvar

Sets the http-variable name that holds the password used to authenticate. If this argument is set then the form detection is not performed. Use the other arguments to define the form manually.

http-form-brute.path

Identifies the page that contains the form (default: "/"). The script analyses the content of this page to determine the form destination, method, and fields. If argument passvar is specified then the form detection is not performed and the path argument is instead used as the form submission destination (the form action). Use the other arguments to define the rest of the form manually as necessary.

http-form-brute.sessioncookies

Attempt to grab session cookies before submitting the form. Setting this to "false" could speed up cracking against forms that do not require any cookies to be set before logging in. Default: true

http-form-brute.uservar

(optional) sets the form field name that holds the username used to authenticate.

creds.global

Credentials to be returned by Credentials.getCredentials regardless of the service.

creds.[service]

Credentials to be returned by Credentials.getCredentials for [service]. E.g. creds.http=admin:password

passdb

The filename of an alternate password database. Default: nselib/data/passwords.lst

unpwdb.passlimit

The maximum number of passwords passwords will return (default unlimited).

unpwdb.timelimit

The maximum amount of time that any iterator will run before stopping. The value is in seconds by default and you can follow it with ms, s, m, or h for milliseconds, seconds, minutes, or hours. For example, unpwdb.timelimit=30m or unpwdb.timelimit=.5h for 30 minutes. The default depends on the timing template level (see the module description). Use the value 0 to disable the time limit.

unpwdb.userlimit

The maximum number of usernames usernames will return (default unlimited).

userdb

The filename of an alternate username database. Default: nselib/data/usernames.lst

brute.credfile

A file containing username and password pairs delimited by '/'

brute.delay

The number of seconds to wait between guesses (default: 0)

brute.emptypass

Guess an empty password for each user (default: false)

brute.firstonly

Stop guessing after first password is found (default: false)

brute.guesses

The number of guesses to perform against each account. (default: 0 (unlimited)). The argument can be used to prevent account lockouts.

brute.mode

Can be user, pass or creds and determines what mode to run the engine in.

  • user - the unpwdb library is used to guess passwords, every password Password is tried for each user. (The user iterator is in the outer loop)
  • pass - the unpwdb library is used to guess passwords, each password Is tried for every user. (The password iterator is in the outer loop)
  • creds - a set of credentials (username and password pairs) are Guessed against the service. This allows for lists of known or common username and password combinations to be tested. If no mode is specified and the script has not added any custom iterator the pass mode will be enabled.

brute.passonly

Iterate over passwords only for services that provide only a password for authentication. (default: false)

brute.retries

The number of times to retry if recoverable failures occur. (default: 2)

brute.start

The number of threads the engine will start with. (default: 5).

brute.threads

The number of initial worker threads, the number of active threads will be automatically adjusted.

brute.unique

Make sure that each password is only guessed once (default: true)

brute.useraspass

Guess the username as password for each user (default: true)

creds.[service]

Credentials to be returned by Credentials.getCredentials for [service]. E.g. creds.http=admin:password

smbdomain

The domain to log in with. If you aren't in a domain environment, then anything will (should?) be accepted by the server.

smbhash

A password hash to use when logging in. This is given as a single hex string (32 characters) or a pair of hex strings (both 32 characters, optionally separated by a single character). These hashes are the LanMan or NTLM hash of the user's password, and are stored on disk or in memory. They can be retrieved from memory using the fgdump or pwdump tools.

smbnoguest

Use to disable usage of the 'guest' account.

smbpassword

The password to connect with. Be cautious with this, since some servers will lock accounts if the incorrect password is given. Although it's rare that the Administrator account can be locked out, in the off chance that it can, you could get yourself in trouble. To use a blank password, leave this parameter off altogether.

smbtype

The type of SMB authentication to use. These are the possible options:

  • v1: Sends LMv1 and NTLMv1.
  • LMv1: Sends LMv1 only.
  • NTLMv1: Sends NTLMv1 only (default).
  • v2: Sends LMv2 and NTLMv2.
  • LMv2: Sends LMv2 only.
  • NTLMv2: Doesn't exist; the protocol doesn't support NTLMv2 alone. The default, NTLMv1, is a pretty decent compromise between security and compatibility. If you are paranoid, you might want to use v2 or lmv2 for this. (Actually, if you're paranoid, you should be avoiding this protocol altogether!). If you're using an extremely old system, you might need to set this to v1 or lm, which are less secure but more compatible. For information, see smbauth.lua.

smbusername

The SMB username to log in with. The forms "DOMAIN\username" and "username@DOMAIN" are not understood. To set a domain, use the smbdomain argument.

slaxml.debug

Debug level at which default callbacks will print detailed parsing info. Default: 3

http.host

The value to use in the Host header of all requests unless otherwise set. By default, the Host header uses the output of stdnse.get_hostname().

http.max-body-size

Limit the received body to specific number of bytes. An oversized body results in an error unless script argument http.truncated-ok or request option truncated_ok is set to true. The default is 2097152 (2MB). Use value -1 to disable the limit altogether. This argument can be overridden case-by-case with request option max_body_size.

http.max-cache-size

The maximum memory size (in bytes) of the cache.

http.max-pipeline

If set, it represents the number of outstanding HTTP requests that should be sent together in a single burst. Defaults to http.pipeline (if set), or to what function get_pipeline_limit returns.

http.pipeline

If set, it represents the number of HTTP requests that'll be sent on one connection. This can be set low to make debugging easier, or it can be set high to test how a server reacts (its chosen max is ignored).

http.truncated-ok

Do not treat oversized body as error. (Use response object flag truncated to check if the returned body has been truncated.) This argument can be overridden case-by-case with request option truncated_ok.

http.useragent

The value of the User-Agent header field sent with requests. By default it is "Mozilla/5.0 (compatible; Nmap Scripting Engine; https://nmap.org/book/nse.html)". A value of the empty string disables sending the User-Agent header field.

- - -
To use these script arguments, add them to the Nmap command line using the --script-args arg1=value,[arg2=value,..] syntax. For example:

nmap --script=http-form-brute --script-args http-form-brute.hostname=value,http-form-brute.method=value <target>

Http-form-brute NSE Script Example Usage

Here's an example of how to use the http-form-brute.nse script:

nmap --script http-form-brute -p 80 <host>

Http-form-brute NSE Script Example Output

Here's a sample output from the http-form-brute.nse script:

PORT     STATE SERVICE REASON
80/tcp   open  http    syn-ack
| http-form-brute:
|   Accounts
|     Patrik Karlsson:secret - Valid credentials
|   Statistics
|_    Perfomed 60023 guesses in 467 seconds, average tps: 138

Http-form-brute NSE Script Example XML Output

There is no sample XML output for this module. However, by providing the -oX <file> option, Nmap will produce a XML output and save it in the file.xml file.

Authors

  • Patrik Karlsson
  • nnposter

References

See Also

Related NSE scripts to the http-form-brute.nse script:

Visit Nmap NSE Library for more scripts.

The http-form-brute.nse script may fail with the following error messages. Check for the possible causes by using the code snippets highlighted below found in the script source code. This can often times help in identifying the root cause of the problem.

Unable to login%.

Here is a relevant code snippet related to the "Unable to login%." error message:

182:	      local body = response.body
183:	      local rpath = response.header.location
184:	      return response.status < 300 and body and not (
185:	        (rpath and rpath:match('logonError%.jsp'))
186:	        or (
187:	          body:match('Unable to login%.') or
188:	          body:match('Login failed%.') or
189:	          body:match('Invalid User ID or password')
190:	          )
191:	        )
192:	    end,

Login failed%.

Here is a relevant code snippet related to the "Login failed%." error message:

183:	      local rpath = response.header.location
184:	      return response.status < 300 and body and not (
185:	        (rpath and rpath:match('logonError%.jsp'))
186:	        or (
187:	          body:match('Unable to login%.') or
188:	          body:match('Login failed%.') or
189:	          body:match('Invalid User ID or password')
190:	          )
191:	        )
192:	    end,
193:	    sessioncookies = false,

Invalid User ID or password

Here is a relevant code snippet related to the "Invalid User ID or password" error message:

184:	      return response.status < 300 and body and not (
185:	        (rpath and rpath:match('logonError%.jsp'))
186:	        or (
187:	          body:match('Unable to login%.') or
188:	          body:match('Login failed%.') or
189:	          body:match('Invalid User ID or password')
190:	          )
191:	        )
192:	    end,
193:	    sessioncookies = false,
194:	  },

Unable to retrieve a login form from path %q

Here is a relevant code snippet related to the "Unable to retrieve a login form from path %q" error message:

241:	  local response = http.get(host, port, path, {
242:	    bypass_cache = true,
243:	    header = {Host = hostname}
244:	  })
245:	  if not (response and response.body and response.status == 200) then
246:	    return nil, string.format("Unable to retrieve a login form from path %q", path)
247:	  end
248:	
249:	  for _, f in pairs(http.grab_forms(response.body)) do
250:	    local form = http.parse_form(f)
251:	    for app, val in pairs(known_apps) do

Unable to detect a login form at path %q

Here is a relevant code snippet related to the "Unable to detect a login form at path %q" error message:

306:	      form.passvar = (ptfld or pnfld).name
307:	      return form, nil, response.cookies
308:	    end
309:	  end
310:	
311:	  return nil, string.format("Unable to detect a login form at path %q", path)
312:	end
313:	
314:	-- TODO: expire cookies
315:	local function update_cookies (old, new)
316:	  for i, c in ipairs(new) do

Failed to get new session cookies: %s

Here is a relevant code snippet related to the "Failed to get new session cookies: %s" error message:

393:	    end
394:	    if self.options.sessioncookies and not (thread.opts.cookies and next(thread.opts.cookies)) then
395:	      -- grab new session cookies
396:	      local form, errmsg, cookies = detect_form(self.host, self.port, path, self.options.hostname)
397:	      if not form then
398:	        stdnse.debug1("Failed to get new session cookies: %s", errmsg)
399:	      else
400:	        thread.opts.cookies = cookies
401:	        thread.params = form.fields
402:	      end
403:	    end

Form submission failed

Here is a relevant code snippet related to the "Form submission failed" error message:

452:	  end,
453:	
454:	  login = function (self, username, password)
455:	    local response, success = self:submit_form(username, password)
456:	    if not response then
457:	      local err = brute.Error:new("Form submission failed")
458:	      err:setRetry(true)
459:	      return false, err
460:	    end
461:	    if not success then
462:	      return false, brute.Error:new("Incorrect password")

Incorrect password

Here is a relevant code snippet related to the "Incorrect password" error message:

457:	      local err = brute.Error:new("Form submission failed")
458:	      err:setRetry(true)
459:	      return false, err
460:	    end
461:	    if not success then
462:	      return false, brute.Error:new("Incorrect password")
463:	    end
464:	    return true, creds.Account:new(username, password, creds.State.VALID)
465:	  end,
466:	
467:	  disconnect = function (self)

Unusable form action %q

Here is a relevant code snippet related to the "Unusable form action %q" error message:

510:	    sessioncookies = form.sessioncookies == nil and sessioncookies or form.sessioncookies
511:	  end
512:	
513:	  -- path should not change the origin
514:	  if not path_ok(path, hostname, port) then
515:	    return stdnse.format_output(false, string.format("Unusable form action %q", path))
516:	  end
517:	  stdnse.debug(form_debug, "Form submission path: " .. path)
518:	
519:	  -- HTTP method POST is the default
520:	  method = string.upper(method or "POST")

Invalid HTTP method %q

Here is a relevant code snippet related to the "Invalid HTTP method %q" error message:

517:	  stdnse.debug(form_debug, "Form submission path: " .. path)
518:	
519:	  -- HTTP method POST is the default
520:	  method = string.upper(method or "POST")
521:	  if not (method == "GET" or method == "POST") then
522:	    return stdnse.format_output(false, string.format("Invalid HTTP method %q", method))
523:	  end
524:	  stdnse.debug(form_debug, "HTTP method: " .. method)
525:	
526:	  -- passvar must be specified or detected, uservar is optional
527:	  if not passvar then

No passvar was specified or detected (see http-form-brute.passvar)

Here is a relevant code snippet related to the "No passvar was specified or detected (see http-form-brute.passvar)" error message:

523:	  end
524:	  stdnse.debug(form_debug, "HTTP method: " .. method)
525:	
526:	  -- passvar must be specified or detected, uservar is optional
527:	  if not passvar then
528:	    return stdnse.format_output(false, "No passvar was specified or detected (see http-form-brute.passvar)")
529:	  end
530:	  stdnse.debug(form_debug, "Username field: " .. (uservar or "(not set)"))
531:	  stdnse.debug(form_debug, "Password field: " .. passvar)
532:	
533:	  if onsuccess and onfailure then

Either the onsuccess or onfailure argument should be passed, not both.

Here is a relevant code snippet related to the "Either the onsuccess or onfailure argument should be passed, not both." error message:

529:	  end
530:	  stdnse.debug(form_debug, "Username field: " .. (uservar or "(not set)"))
531:	  stdnse.debug(form_debug, "Password field: " .. passvar)
532:	
533:	  if onsuccess and onfailure then
534:	    return stdnse.format_output(false, "Either the onsuccess or onfailure argument should be passed, not both.")
535:	  end
536:	
537:	  -- convert onsuccess and onfailure to functions
538:	  local is_success = onsuccess and (
539:	    type(onsuccess) == "function" and onsuccess

Failed to submit the form to path %q

Here is a relevant code snippet related to the "Failed to submit the form to path %q" error message:

571:	  local username = uservar and rand.random_alpha(8)
572:	  local password = rand.random_alpha(8)
573:	  local testdrv = Driver:new(host, port, options)
574:	  local response, success = testdrv:submit_form(username, password)
575:	  if not response then
576:	    return stdnse.format_output(false, string.format("Failed to submit the form to path %q", path))
577:	  end
578:	  if success then
579:	    return stdnse.format_output(false, "Failed to recognize failed authentication. See http-form-brute.onsuccess and http-form-brute.onfailure")
580:	  end
581:

Failed to recognize failed authentication. See http-form-brute.onsuccess and http-form-brute.onfailure

Here is a relevant code snippet related to the "Failed to recognize failed authentication. See http-form-brute.onsuccess and http-form-brute.onfailure" error message:

574:	  local response, success = testdrv:submit_form(username, password)
575:	  if not response then
576:	    return stdnse.format_output(false, string.format("Failed to submit the form to path %q", path))
577:	  end
578:	  if success then
579:	    return stdnse.format_output(false, "Failed to recognize failed authentication. See http-form-brute.onsuccess and http-form-brute.onfailure")
580:	  end
581:	
582:	  local engine = brute.Engine:new(Driver, host, port, options)
583:	  -- there's a bug in http.lua that does not allow it to be called by
584:	  -- multiple threads

Version

This page has been created based on Nmap version 7.92.

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