CORStest inital commit

LICENSE

@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc., <http://fsf.org/>
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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+    {description}
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+The hypothetical commands `show w' and `show c' should show the appropriate
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+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  {signature of Ty Coon}, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
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+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

README.md

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+## CORStest
+### A simple CORS misconfigurations checker
+
+**Based on the research of [James Kettle](https://twitter.com/albinowax)**
+
+CORStest is a *quick & dirty* Python 2 tool to find Cross-Origin Resource Sharing ([CORS](https://www.w3.org/TR/cors/)) misconfigurations. It takes a text file as input which may contain a list of domain names or URLs. Currently, the following potential vulnerabilities are detected by sending a certain `Origin` request header and checking for the `Access-Control-Allow-Origin` response header:
+
+- **Developer backdoor:** Insecure dev origins like JSFiddle or CodePen are allowed to access this resource
+- **Origin reflection:** The origin is simply echoed in ACAO header, any site is allowed to access this resource
+- **Null misconfiguration:** Any site is allowed to access by forcing the `null` origin via a sandboxed iframe
+- **Pre-domain wildcard:** *not*domain.com is allowed access, which can simply be registered by an attacker
+- **Post-domain wildcard:** domain.com.*evil.com* is allowed access, which can be registered by an attacker
+- **Subdomains allowed:** *sub*.domain.com allowed access, exploitable if attacker finds XSS in any subdomain
+- **Non-ssl sites allowed:** A http origin is allowed access to a https resource, allows MitM to break encryption
+- **Invalid CORS header:** Wrong use of wildcard or multiple origins, not a security problem but should be fixed
+
+Note that these vulnerabilities/misconfigurations are dependend on the context. In most scenarios, they can only be exploited by an attacker if the `Access-Control-Allow-Credentials header` is present (see `-q` flag).
+
+### Usage
+
+```
+usage: corstest.py [arguments] infile
+
+positional arguments:
+  infile         File with domain or URL list
+
+optional arguments:
+  -h, --help     show this help message and exit
+  -c name=value  Send cookie with all requests
+  -p processes   multiprocessing (default: 32)
+  -s             always force ssl/tls requests
+  -q             quiet, allow-credentials only
+  -v             produce a more verbose output
+```
+
+### Example
+
+Use of CORStest to detect misconfigurations for the Alexa top 750 sites (with `Access-Control-Allow-Credentials`):
+
+![CORStest example with Alexa top 750 websites](img/example-alexa-750.gif)
+
+### Evaluation
+
+Running this CORStest on the  Alexa [top 1 million](http://s3.amazonaws.com/alexa-static/top-1m.csv.zip) sites reveals the following results:
+
+![CORStest example with Alexa top 1,000,000 sites](img/evaluation-alexa-1m.png)
+
+Note that the absolute numbers are quite low, because only 3% of the 1,000,000 tested websites had CORS enabled on their main page and could be analyzed for misconfigurations. This test took about 14 hours on a decent line (DSL). If you have a fast Internet connection, try to increase the number of parallel processes to `-p50` or more.
+
+### Background
+
+Read more on the technical backgorund of CORS misconfigurations in this fine [blogpost](http://blog.portswigger.net/2016/10/exploiting-cors-misconfigurations-for.html) or check out this [talk](https://www.youtube.com/watch?v=wgkj4ZgxI4c).

corstest.py

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+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# python standard library
+import re, sys, ssl, signal, urllib2, urlparse, argparse, multiprocessing
+
+# -------------------------------------------------------------------------------------------------
+
+def usage():
+  parser = argparse.ArgumentParser(description="Simple CORS misconfigurations checker")
+  parser.add_argument("infile", help="File with domain or URL list")
+  parser.add_argument("-c", metavar="name=value", help="Send cookie with all requests")
+  parser.add_argument("-p", metavar="processes", help="multiprocessing (default: 32)")
+  parser.add_argument("-s", help="always force ssl/tls requests", action="store_true")
+  parser.add_argument("-q", help="quiet, allow-credentials only", action="store_true")
+  parser.add_argument("-v", help="produce a more verbose output", action="store_true")
+  return parser.parse_args()
+
+# -------------------------------------------------------------------------------------------------
+
+def main():
+  global args; args = usage()
+  try:
+    urls = [line.rstrip() for line in open(args.infile)]
+    procs = min(abs(int(args.p or 32)), len(urls)) or 1
+  except (IOError, ValueError) as e: print e; return
+  # check domains/urls in parallel but clean exit on ctrl-c
+  sigint_handler = signal.signal(signal.SIGINT, signal.SIG_IGN)
+  pool = multiprocessing.Pool(processes=procs)
+  signal.signal(signal.SIGINT, sigint_handler)
+  try: pool.map_async(check, urls).get(2**32)
+  except KeyboardInterrupt: pass
+
+# -------------------------------------------------------------------------------------------------
+
+# check for vulns/misconfigurations
+def check(url):
+  if re.findall("^https://", url): args.s = True     # set protocol
+  url = re.sub("^https?://", "", url)                # url w/o proto
+  host = urlparse.urlparse("//"+url).hostname or ""  # set hostname
+  acao = cors(url, url, False, True)                 # perform request
+  if acao:
+    if args.q and (acao == "no_acac" or "*" == acao): return
+    if acao == "*": info(url, "* (without credentials)")
+    elif acao in ["//", "://"]: alert(url, "Any origin allowed") # firefox/chrome/safari/opera only
+    elif re.findall("\s|,|\|", acao): invalid(url, "Multiple values in Access-Control-Allow-Origin")
+    elif re.findall("\*.", acao): invalid(url, 'Wrong use of wildcard, only single "*" is valid')
+    elif re.findall("fiddle.jshell.net|s.codepen.io", acao): alert(url, "Developer backdoor")
+    elif "evil.org" in cors(url, "evil.org"): alert(url, "Origin reflection")
+    elif "null" == cors(url, "null").lower(): alert(url, "Null misconfiguration")
+    elif host+".tk" in cors(url, host+".tk"): alert(url, "Post-domain wildcard")
+    elif "not"+host in cors(url, "not"+url):
+      alert(url, "Pre-domain wildcard") if sld(host) else warning(url, "Pre-subdomain wildcard")
+    elif "sub."+host in cors(url, "sub."+url): warning(url, "Arbitrary subdomains allowed")
+    elif cors(url, url, True).startswith("http://"): warning(url, "Non-ssl site allowed")
+    else: info(url, acao)
+  elif acao != None and not args.q: notvuln(url, "Access-Control-Allow-Origin header not present")
+  # TBD: maybe use CORS preflight options request instead to check if cors protocol is understood
+  sys.stdout.flush()
+
+# -------------------------------------------------------------------------------------------------
+
+# perform request and fetch response header
+def cors(url, origin, ssltest=False, firstrun=False):
+  url = ("http://" if not (ssltest or args.s) else "https://") + url
+  if origin != "null": origin = ("http://" if (ssltest or not args.s) else "https://") + origin
+  try:
+    request = urllib2.Request(url)
+    request.add_header('Origin', origin)
+    request.add_header('Cookie', args.c or "")
+    request.add_header('User-Agent', 'Mozilla/5.0 (Windows NT 6.1; WOW64)')
+    if not "_create_unverified_context" in dir(ssl): response = urllib2.urlopen(request, timeout=10)
+    else: response = urllib2.urlopen(request, timeout=10, context=ssl._create_unverified_context())
+    acao = response.info().getheader('Access-Control-Allow-Origin')
+    acac = str(response.info().getheader('Access-Control-Allow-Credentials')).lower() == "true"
+    vary = "Origin" in str(response.info().getheader('Vary'))
+    if args.v: print "%s\n%-10s%s\n%-10s%s\n%-10s%s\n%-10s%s" % ("-" * 72, "Resource:", \
+               response.geturl(), "Origin:", origin, "ACAO:", acao or "-", "ACAC:", acac or "-")
+    if firstrun:
+      if args.q and not acac: acao = "no_acac"
+      if acac and acao != '*' and not args.q: alert(url, "Access-Control-Allow-Credentials present")
+      if vary and not args.q: warning(url, "Access-Control-Allow-Origin dynamically generated")
+    if ssltest and response.info().getheader('Strict-Transport-Security'): acao = ""
+    return acao or ""
+  except Exception as e:
+    if not args.q: error(url, e.message or str(e).splitlines()[-1])
+    if not firstrun: return ""
+
+# -------------------------------------------------------------------------------------------------
+
+# check if given hostname is a second-level domain
+def sld(host):
+  try:
+    with open('tldlist.dat') as f: tlds = [line.strip() for line in f if line[0] not in "/\n"][::-1]
+  except IOError as e: return True
+  for tld in tlds:
+    if host.endswith('.' + tld): host = host[:-len(tld)]
+  if host.count('.') == 1: return True
+
+# -------------------------------------------------------------------------------------------------
+
+def error(url, msg): print "\x1b[2m" + url, "- Error:", msg + "\x1b[0m"
+def alert(url, msg): print "\x1b[97;41m" + url, "- Alert:", msg + "\x1b[0m"
+def invalid(url, msg): print "\x1b[30;43m" + url, "- Invalid:", msg + "\x1b[0m"
+def warning(url, msg): print "\x1b[30;48;5;202m" + url, "- Warning:", msg + "\x1b[0m"
+def notvuln(url, msg): print "\x1b[97;100m" + url, "- Not vulnerable:", msg + "\x1b[0m"
+def info(url, msg): print "\x1b[30;42m" + url, "- Access-Control-Allow-Origin:", msg + "\x1b[0m"
+
+# -------------------------------------------------------------------------------------------------
+
+if __name__ == '__main__':
+  main()