anti
24f02c3466
- Add # nosec B104 to all intentional 0.0.0.0 binds in honeypot servers (hardcoded_bind_all_interfaces is by design — deckies must accept attacker connections) - Add # nosec B101 to assert statements used for protocol validation in ldap/snmp - Add # nosec B105 to fake SASL placeholder in ldap - Add # nosec B108 to /tmp usage in smb template - Exclude root-owned auto-generated decnet_logging.py copies from bandit scan via pyproject.toml [tool.bandit] config (synced by _sync_logging_helper at deploy)
105 lines
3.8 KiB
Python
105 lines
3.8 KiB
Python
#!/usr/bin/env python3
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"""
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SMTP server — emulates a realistic ESMTP server (Postfix-style).
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Logs EHLO/AUTH/MAIL FROM/RCPT TO attempts as JSON, then denies auth.
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"""
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import asyncio
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import os
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from decnet_logging import syslog_line, write_syslog_file, forward_syslog
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NODE_NAME = os.environ.get("NODE_NAME", "mailserver")
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SERVICE_NAME = "smtp"
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LOG_TARGET = os.environ.get("LOG_TARGET", "")
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_SMTP_BANNER = os.environ.get("SMTP_BANNER", f"220 {NODE_NAME} ESMTP Postfix (Debian/GNU)")
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_SMTP_MTA = os.environ.get("SMTP_MTA", NODE_NAME)
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def _log(event_type: str, severity: int = 6, **kwargs) -> None:
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line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
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print(line, flush=True)
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write_syslog_file(line)
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forward_syslog(line, LOG_TARGET)
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class SMTPProtocol(asyncio.Protocol):
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def __init__(self):
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self._transport = None
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self._peer = ("?", 0)
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self._buf = b""
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def connection_made(self, transport):
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self._transport = transport
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self._peer = transport.get_extra_info("peername", ("?", 0))
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_log("connect", src=self._peer[0], src_port=self._peer[1])
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transport.write(f"{_SMTP_BANNER}\r\n".encode())
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def data_received(self, data):
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self._buf += data
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while b"\r\n" in self._buf:
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line, self._buf = self._buf.split(b"\r\n", 1)
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self._handle_line(line.decode(errors="replace").strip())
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def _handle_line(self, line: str) -> None:
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cmd = line.split()[0].upper() if line.split() else ""
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if cmd in ("EHLO", "HELO"):
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domain = line.split(None, 1)[1] if " " in line else ""
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_log("ehlo", src=self._peer[0], domain=domain)
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self._transport.write(
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f"250-{_SMTP_MTA}\r\n"
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f"250-PIPELINING\r\n"
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f"250-SIZE 10240000\r\n"
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f"250-VRFY\r\n"
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f"250-ETRN\r\n"
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f"250-AUTH PLAIN LOGIN\r\n"
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f"250-ENHANCEDSTATUSCODES\r\n"
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f"250-8BITMIME\r\n"
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f"250 DSN\r\n".encode()
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)
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elif cmd == "AUTH":
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_log("auth_attempt", src=self._peer[0], command=line)
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self._transport.write(b"535 5.7.8 Error: authentication failed: UGFzc3dvcmQ6\r\n")
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self._transport.close()
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elif cmd == "MAIL":
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_log("mail_from", src=self._peer[0], value=line)
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self._transport.write(b"250 2.1.0 Ok\r\n")
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elif cmd == "RCPT":
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_log("rcpt_to", src=self._peer[0], value=line)
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self._transport.write(b"250 2.1.5 Ok\r\n")
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elif cmd == "DATA":
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self._transport.write(b"354 End data with <CR><LF>.<CR><LF>\r\n")
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elif cmd == "VRFY":
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_log("vrfy", src=self._peer[0], value=line)
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self._transport.write(b"252 2.0.0 Cannot VRFY user\r\n")
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elif cmd == "QUIT":
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self._transport.write(b"221 2.0.0 Bye\r\n")
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self._transport.close()
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elif cmd == "NOOP":
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self._transport.write(b"250 2.0.0 Ok\r\n")
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elif cmd == "RSET":
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self._transport.write(b"250 2.0.0 Ok\r\n")
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elif cmd == "STARTTLS":
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# Pretend we don't support upgrading mid-session
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self._transport.write(b"454 4.7.0 TLS not available due to local problem\r\n")
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else:
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_log("unknown_command", src=self._peer[0], command=line)
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self._transport.write(b"502 5.5.2 Error: command not recognized\r\n")
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def connection_lost(self, exc):
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_log("disconnect", src=self._peer[0] if self._peer else "?")
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async def main():
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_log("startup", msg=f"SMTP server starting as {NODE_NAME}")
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loop = asyncio.get_running_loop()
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server = await loop.create_server(SMTPProtocol, "0.0.0.0", 25) # nosec B104
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async with server:
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await server.serve_forever()
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if __name__ == "__main__":
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asyncio.run(main())
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