description = [[ Attempts to bypass password protected resources (HTTP 401 status) by performing HTTP verb tampering. If an array of paths to check is not set, it will crawl the web server and perform the check against any password protected resource that it finds. The script determines if the protected URI is vulnerable by performing HTTP verb tampering and monitoring the status codes. First, it uses a HEAD request, then a POST request and finally a random generated string ( This last one is useful when web servers treat unknown request methods as a GET request. This is the case for PHP servers ). If the table paths is set, it will attempt to access the given URIs. Otherwise, a web crawler is initiated to try to find protected resources. Note that in a PHP environment with .htacess files you need to specify a path to a file rather than a directory to find misconfigured .htaccess files. References: * http://www.imperva.com/resources/glossary/http_verb_tampering.html * https://www.owasp.org/index.php/Testing_for_HTTP_Methods_and_XST_%28OWASP-CM-008%29 * http://www.mkit.com.ar/labs/htexploit/ * http://capec.mitre.org/data/definitions/274.html ]] --- -- @usage nmap -sV --script http-method-tamper -- @usage nmap -p80 --script http-method-tamper --script-args 'http-method-tamper.paths={/protected/db.php,/protected/index.php}' -- -- @output -- PORT STATE SERVICE REASON -- 80/tcp open http syn-ack -- | http-method-tamper: -- | VULNERABLE: -- | Authentication bypass by HTTP verb tampering -- | State: VULNERABLE (Exploitable) -- | Description: -- | This web server contains password protected resources vulnerable to authentication bypass -- | vulnerabilities via HTTP verb tampering. This is often found in web servers that only limit access to the -- | common HTTP methods and in misconfigured .htaccess files. -- | -- | Extra information: -- | -- | URIs suspected to be vulnerable to HTTP verb tampering: -- | /method-tamper/protected/pass.txt [POST] -- | -- | References: -- | http://www.imperva.com/resources/glossary/http_verb_tampering.html -- | http://www.mkit.com.ar/labs/htexploit/ -- | http://capec.mitre.org/data/definitions/274.html -- |_ https://www.owasp.org/index.php/Testing_for_HTTP_Methods_and_XST_%28OWASP-CM-008%29 -- -- @args http-method-tamper.uri Base URI to crawl. Not aplicable if http-method-tamper.paths is set. -- @args http-method-tamper.paths Array of paths to check. If not set, the script will crawl the web server. -- @args http-method-tamper.timeout Web crawler timeout. Default: 10000ms --- author = "Paulino Calderon " license = "Same as Nmap--See http://nmap.org/book/man-legal.html" categories = {"auth", "vuln"} local http = require "http" local shortport = require "shortport" local stdnse = require "stdnse" local table = require "table" local httpspider = require "httpspider" local vulns = require "vulns" local url = require "url" local string = require "string" portrule = shortport.http -- -- Checks if the web server does not return status 401 when requesting with other HTTP verbs. -- First, it tries with HEAD, POST and then with a random string. -- local function probe_http_verbs(host, port, uri) stdnse.print_debug(2, "%s:Tampering HTTP verbs %s", SCRIPT_NAME, uri) local head_req = http.head(host, port, uri) if head_req and head_req.status ~= 401 then return true, "HEAD" end local post_req = http.post(host, port, uri) if post_req and post_req.status ~= 401 then return true, "POST" end --With a random generated verb we look for 400 and 501 status local random_verb_req = http.generic_request(host, port, stdnse.generate_random_string(4), uri) local retcodes = { [400] = true, -- Bad Request [401] = true, -- Authentication needed [501] = true, -- Invalid method } if random_verb_req and not retcodes[random_verb_req.status] then return true, "GENERIC" end return false end action = function(host, port) local vuln_uris = {} local paths = stdnse.get_script_args(SCRIPT_NAME..".paths") local uri = stdnse.get_script_args(SCRIPT_NAME..".uri") or "/" local timeout = stdnse.get_script_args(SCRIPT_NAME..".timeout") or 10000 local vuln = { title = 'Authentication bypass by HTTP verb tampering', state = vulns.STATE.NOT_VULN, description = [[ This web server contains password protected resources vulnerable to authentication bypass vulnerabilities via HTTP verb tampering. This is often found in web servers that only limit access to the common HTTP methods and in misconfigured .htaccess files. ]], references = { 'http://www.mkit.com.ar/labs/htexploit/', 'http://www.imperva.com/resources/glossary/http_verb_tampering.html', 'https://www.owasp.org/index.php/Testing_for_HTTP_Methods_and_XST_%28OWASP-CM-008%29', 'http://capec.mitre.org/data/definitions/274.html' } } local vuln_report = vulns.Report:new(SCRIPT_NAME, host, port) -- If paths is not set, crawl the web server looking for http 401 status if not(paths) then local crawler = httpspider.Crawler:new(host, port, uri, { scriptname = SCRIPT_NAME } ) crawler:set_timeout(timeout) while(true) do local status, r = crawler:crawl() if ( not(status) ) then if ( r.err ) then return stdnse.format_output(true, "ERROR: %s", r.reason) else break end end if r.response.status == 401 then stdnse.print_debug(2, "%s:%s is protected! Let's try some verb tampering...", SCRIPT_NAME, tostring(r.url)) local parsed = url.parse(tostring(r.url)) local probe_status, probe_type = probe_http_verbs(host, port, parsed.path) if probe_status then stdnse.print_debug(1, "%s:Vulnerable URI %s", SCRIPT_NAME, uri) table.insert(vuln_uris, parsed.path..string.format(" [%s]", probe_type)) end end end else -- Paths were set, check them and exit. No crawling here. -- convert single string entry to table if ( type(paths) == "string" ) then paths = { paths } end -- iterate through given paths/files for _, path in ipairs(paths) do local path_req = http.get(host, port, path) if path_req.status == 401 then local probe_status, probe_type = probe_http_verbs(host, port, path) if probe_status then stdnse.print_debug(1, "%s:Vulnerable URI %s", SCRIPT_NAME, path) table.insert(vuln_uris, path..string.format(" [%s]", probe_type)) end end end end if ( #vuln_uris > 0 ) then vuln.state = vulns.STATE.EXPLOIT vuln_uris.name = "URIs suspected to be vulnerable to HTTP verb tampering:" vuln.extra_info = stdnse.format_output(true, vuln_uris) end return vuln_report:make_output(vuln) end