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Solid as Diamond: using ruby in a web application penetration test

Solid as Diamond: using ruby in a web application penetration test

For Railsberry 2013 I gave a talk on some ruby gems I wrote to automate some security tests I perform during my daytime job.

Enjoy it

Paolo Perego

April 23, 2013

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  1. Solid as Diamond Using Ruby in a web application penetration

    test [email protected] - Railsberry 2013 - Cracow Tuesday, April 23, 13
  2. self.inspect • I do stuff: husband, proud father && martial

    artist • I break other people code for living (only when authorized) • I blog at: http://armoredcode.com • I’m on github too: https:// github.com/thesp0nge • I love twitter: @thesp0nge, @armoredcode 2 Tuesday, April 23, 13
  3. talk.inspect • Owasp Top 10 2013 • Ruby code to...

    • Leverage a web application attack surface • Bruteforce authentication mechanism • Look for Cross site scripting 3 Tuesday, April 23, 13
  4. Change your mindset. You’re an attacker now! 5 Your web

    application is a blackbox You’ve got only a URL as a starting point (optional) You may have a valid user, instead you have to register a user to the application Good luck! Tuesday, April 23, 13
  5. It all starts with... 6 ... someone wants to publish

    a new web application on the Internet or on an Internal network, she gives me the url and she says “test it for security issues, please”... Tuesday, April 23, 13
  6. The Owasp Top 10 - 2013 8 • A1 –

    Injection • A2 – Broken Authentication and Session Management • A3 – Cross-Site Scripting (XSS) • A4 – Insecure Direct Object References • A5 – Security Misconfiguration • A6 – Sensitive Data Exposure • A7 – Missing Function Level Access Control • A8 – Cross-Site Request Forgery (CSRF) • A9 – Using Known Vulnerable Components • A10 – Unvalidated Redirects and Forwards (To be released later this spring) https://www.owasp.org/index.php/Top_10_2013 Tuesday, April 23, 13
  7. Leverage your attack surface 10 Spot attack entrypoints: (robots.txt and

    url discovery with bruteforce) Fingerprint your target Check transport layer security Check for the service door (backup files) Tuesday, April 23, 13
  8. Fingerprint your target 11 • Meta generator tag • Server

    HTTP response field • X-Powered-by HTTP response field • Popular pages with extension (login.do, index.jsp, main.asp, login.php, phpinfo.php...) • The HTTP response field order (soon it will be implemented in the gengiscan gem) Tuesday, April 23, 13
  9. Fingerprint your target 12 def detect(url) uri = URI(url) begin

    res = Net::HTTP.get_response(uri) {:status=>:OK, :code=>res.code, :server=>res['Server'], :powered=>res['X-Powered-By'], :generator=>get_generator_signature(res)} rescue {:status=>:KO, :code=>nil, :server=>nil, :powered=>nil, :generator=>nil} end end def get_generator_signature(res) generator = "" doc=Nokogiri::HTML(res.body) doc.xpath("//meta[@name='generator']/@content").each do |value| generator = value.value end generator end $ gem install gengiscan $ gengiscan http://localhost:4567 {:status=>:OK, :code=>"404", :server=>"WEBrick/1.3.1 (Ruby/ 1.9.3/2012-04-20)", :powered=>nil, :generator=>""} Tuesday, April 23, 13
  10. Spot attack entrypoints 14 # TESTING: SPIDERS, ROBOTS, AND CRAWLERS

    (OWASP-IG-001) def self.robots(site) site = 'http://'+site unless site.start_with? 'http://' or site.start_with? 'https://' allow_list = [] disallow_list = [] begin res=Net::HTTP.get_response(URI(site+'/robots.txt')) return {:status=>:KO, :allow_list=>[], :disallow_list=>[], :error=>"robots.txt response code was #{res.code}"} if (res.code != "200") res.body.split("\n").each do |line| disallow_list << line.split(":")[1].strip.chomp if (line.downcase.start_with?('disallow')) allow_list << line.split(":")[1].strip.chomp if (line.downcase.start_with?('allow')) end rescue Exception => e return {:status=>:KO, :allow_list=>[], :disallow_list=>[], :error=>e.message} end {:status=>:OK, :allow_list=>allow_list, :disallow_list=>disallow_list, :error=>""} end $ gem install codesake_links $ links -r http://localhost:4567 Tuesday, April 23, 13
  11. Spot attack entrypoints 15 • Use a dictionary to discover

    URLs with bruteforce • Very intrusive attack... you’ll be busted, be aware $ gem install codesake_links $ links -b test_case_dir_wordlist.txt http://localhost:4567 Tuesday, April 23, 13
  12. Check transport layer security 16 $ gem install ciphersurfer $

    ciphersurfer www.gmail.com Evaluating secure communication with www.gmail.com:443 Overall evaluation : B (76.5) Protocol support : ooooooooooooooooooooooooooooooooooooooooooooooooooooooo (55) Key exchange : oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo (80) Cipher strength : oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo (90) Evaluate an SSL connection for: • protocols the server supports • cipher length • certificate key length Tuesday, April 23, 13
  13. Check transport layer security 17 def go context=OpenSSL::SSL::SSLContext.new(@proto) cipher_set =

    context.ciphers cipher_set.each do |cipher_name, cipher_version, bits, algorithm_bits| request = Net::HTTP.new(@host, @port) request.use_ssl = true request.verify_mode = OpenSSL::SSL::VERIFY_NONE request.ciphers= cipher_name begin response = request.get("/") @ok_bits << bits @ok_ciphers << cipher_name rescue OpenSSL::SSL::SSLError => e # Quietly discard SSLErrors, really I don't care if the cipher has # not been accepted rescue # Quietly discard all other errors... you must perform all error # chekcs in the calling program end end end protocol_version.each do |version| s = Ciphersurfer::Scanner.new({:host=>host, :port=>port, :proto=>version}) s.go if (s.ok_ciphers.size != 0) supported_protocols << version cipher_bits = cipher_bits | s.ok_bits ciphers = ciphers | s.ok_ciphers end end Tuesday, April 23, 13
  14. Check for the service door 18 require 'anemone' require 'httpclient'

    h=HTTPClient.new() Anemone.crawl(ARGV[0]) do |anemone| anemone.on_every_page do |page| response = h.get(page.url) puts "Original: #{page.url}: #{response.code}" response = h.get(page.url.to_s.split(";")[0].concat(".bak")) puts "BAK: #{page.url.to_s.split(";")[0].concat(".bak")}: #{response.code}" response = h.get(page.url.to_s.split(";")[0].concat(".old")) puts "OLD: #{page.url.to_s.split(";")[0].concat(".old")}: #{response.code}" response = h.get(page.url.to_s.split(";")[0].concat("~")) puts "~: #{page.url.to_s.split(";")[0].concat("~")}: #{response.code}" end end Tuesday, April 23, 13
  15. How do I break this? 25 1. Use an existing

    user to check the HTML <p> Wrong password for admin user </p> 2. Place a canary string to anonymize the output <p> Wrong password for canary_username user </p> 3. Submit the post and check if the response is the one expected with the canary substituted <p> Wrong password for tom user </p> Tuesday, April 23, 13
  16. How do I break this? 26 def post(url, username, password)

    agent = Mechanize.new agent.user_agent_alias = 'Mac Safari' agent.agent.http.verify_mode = OpenSSL::SSL::VERIFY_NONE username_set = false password_set = false page = agent.get(url) page.forms.each do |form| form.fields.each do |field| if field.name.downcase == 'username' or field.name.downcase== 'login' username_set = true field.value = username end if field.name.downcase == 'password' or field.name.downcase== 'pass' or field.name.downcase== 'pwd' password_set = true field.value = password end end return agent.submit(form) if username_set and password_set end return nil end Tuesday, April 23, 13
  17. How do I break this? 27 log("existing user #{username} used

    as canary") wrong_pwd = post(url, username, "caosintheground").body.gsub(username, 'canary_username') wrong_creds = post(url, "caostherapy", "caosintheground").body.gsub("caostherapy", "canary_username") if ! line.start_with?("#") sleep(@sleep_time) log("awake... probing with: #{line}") r= post(url, line, ".4nt4n1") found << line if r.body == wrong_pwd.gsub("canary_username", line) end Tuesday, April 23, 13
  18. Look for Cross Site Scripting 33 • In GETs •

    Submit the attack payload as parameter in the query string • Parse HTML and check if payload is in the script nodes • In POSTs • Get the page • Find the form(s) • Fill the form input values with attack payload • Submit the form • Parse HTML and check if payload is in the script nodes Tuesday, April 23, 13
  19. Look for Cross Site Scripting 34 attack_url = Cross::Url.new(url) Cross::Attack::XSS.each

    do |pattern| attack_url.params.each do |par| page = @agent.get(attack_url.fuzz(par[:name],pattern)) @agent.log.debug(page.body) if debug? scripts = page.search("//script") scripts.each do |sc| found = true if sc.children.text.include?("alert('cross canary')") @agent.log.debug(sc.children.text) if @options[:debug] end attack_url.reset end end Exploiting GETs... $ gem install cross $ cross -u http://localhost:4567/hello?name=paolo Tuesday, April 23, 13
  20. Look for Cross Site Scripting 35 begin page = @agent.get(url)

    rescue Mechanize::UnauthorizedError puts 'Authentication failed. Giving up.' return false rescue Mechanize::ResponseCodeError puts 'Server gave back 404. Giving up.' return false end puts "#{page.forms.size} form(s) found" if debug? page.forms.each do |f| f.fields.each do |ff| ff.value = "<script>alert('cross canary');</script>" end pp = @agent.submit(f) puts "#{pp.body}" if debug? scripts = pp.search("//script") scripts.each do |sc| found = true if sc.children.text == "alert('cross canary');" end end Exploiting POSTs... $ gem install cross $ cross http://localhost:4567/login Tuesday, April 23, 13
  21. What we learnt 38 • Don’t trust your users •

    “Security through obscurity” is EVIL • Testing for security issues is a mandatory step before deploy • HTTPS won’t safe from XSS or SQL Injections Tuesday, April 23, 13
  22. Some links before we leave 39 http://armoredcode.com/blog/categories/pentest-with-ruby/ https://github.com/codesake http://ronin-ruby.github.com/ https://github.com/rapid7/metasploit-framework

    http://www.owasp.org http://brakemanscanner.org/ Not mine, here because they’re cool http://www.youtube.com/user/armoredcodedotcom Tuesday, April 23, 13