anti
19271f9319
- asyncio.Protocol (TCP): _transport: asyncio.Transport | None = None + cast() in connection_made; assert guards in every method that directly accesses the field. Files: pop3, smtp, mqtt, postgres, mssql, mongodb, imap, ldap, redis, mysql, sip, vnc. - asyncio.DatagramProtocol (UDP): _transport: asyncio.DatagramTransport | None = None. Files: snmp, tftp, SIPUDPProtocol. - RDP: assert new_transport is not None after start_tls() to narrow Transport | None. - FTP (Twisted): assert self.transport is not None + targeted type: ignore for imprecise Twisted stubs (misc/override/arg-type/attr-defined), IReactorTCP cast for listenTCP. - conpot: proc.stdout is None guard before iteration. - Bonus fixes surfaced by annotation: - smtp: get_payload(decode=True) bytes narrowing (arg-type on sha256) - postgres: rename shadowed `msg` param to `err_msg` in _handle_startup - mongodb: base64.binascii.Error → import binascii; binascii.Error - imap: result: list[int] = [] (var-annotated)
110 lines
3.8 KiB
Python
110 lines
3.8 KiB
Python
#!/usr/bin/env python3
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"""
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VNC (RFB)server.
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Performs the RFB 3.8 handshake, offers VNC authentication, captures the
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24-byte DES-encrypted challenge response, then rejects with "Authentication
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failed". Logs the raw response for offline cracking.
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"""
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import asyncio
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import os
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import base64 as _base64
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from typing import cast
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from syslog_bridge import syslog_line, write_syslog_file, forward_syslog
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NODE_NAME = os.environ.get("NODE_NAME", "desktop")
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SERVICE_NAME = "vnc"
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LOG_TARGET = os.environ.get("LOG_TARGET", "")
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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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write_syslog_file(line)
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forward_syslog(line, LOG_TARGET)
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class VNCProtocol(asyncio.Protocol):
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_transport: asyncio.Transport | None = None
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_peer: tuple[str, int] | None = None
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def __init__(self):
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self._transport = None
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self._peer = None
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self._buf = b""
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self._state = "version"
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def connection_made(self, transport: asyncio.BaseTransport) -> None:
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self._transport = cast(asyncio.Transport, transport)
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self._peer = cast(tuple[str, int], self._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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# Send RFB version
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self._transport.write(b"RFB 003.008\n")
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def data_received(self, data):
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self._buf += data
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self._process()
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def _process(self) -> None:
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assert self._transport is not None
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assert self._peer is not None
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if self._state == "version":
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if b"\n" not in self._buf:
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return
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line, self._buf = self._buf.split(b"\n", 1)
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client_version = line.decode(errors="replace").strip()
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_log("version", src=self._peer[0], client_version=client_version)
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# Send security types: 1 type = VNC Authentication (2)
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self._transport.write(b"\x01\x02")
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self._state = "security_choice"
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elif self._state == "security_choice":
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if len(self._buf) < 1:
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return
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chosen = self._buf[0]
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self._buf = self._buf[1:]
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_log("security_choice", src=self._peer[0], type=chosen)
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# Send 16-byte challenge
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self._transport.write(os.urandom(16))
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self._state = "auth_response"
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elif self._state == "auth_response":
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if len(self._buf) < 16:
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return
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response = self._buf[:16]
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self._buf = self._buf[16:]
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# VNC protocol: 16-byte DES-encrypted challenge. Plaintext
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# password is irrecoverable, so we land this credential as
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# secret_kind="vnc_des_response" — secret_b64 carries the
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# raw 16 bytes for content-addressable within-kind reuse.
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_hex = response.hex()
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_log("auth_response", src=self._peer[0],
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response=_hex,
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secret_kind="vnc_des_response",
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secret_printable=_hex,
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secret_b64=_base64.b64encode(response).decode("ascii"))
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# SecurityResult: 1 = failed
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self._transport.write(b"\x00\x00\x00\x01")
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# Failure reason
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reason = b"Authentication failed"
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import struct
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self._transport.write(struct.pack(">I", len(reason)) + reason)
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self._transport.close()
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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"VNC server starting as {NODE_NAME}")
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loop = asyncio.get_running_loop()
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server = await loop.create_server(VNCProtocol, "0.0.0.0", 5900) # 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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