Files
DECNET/decnet/services/rdp.py
anti b3d1301925 feat(creds): DEBT-040 Phase 3 — RDP NLA / CredSSP NTLMv2 capture
When RDP_ENABLE_NLA=true (service_cfg.nla=true on the topology side),
confirm PROTOCOL_HYBRID on the X.224 Connection Confirm, upgrade the
socket to TLS using a self-signed cert generated at first start by
the entrypoint, then drive a tiny CredSSP loop:

- Read inbound TSRequest DER (bounded to MAX_TSREQUEST_LEN).
- Scan for the NTLMSSP signature, dispatch on message type:
  Type 1 -> respond with a hand-built TSRequest carrying our Type 2
  challenge. Type 3 -> parse_type3() and emit auth_attempt with the
  universal credential SD shape (secret_kind = ntlmssp_v2).
- Hand-built DER: no pyasn1 dependency.

Also folds in a small fix-up to commit 1: SMB SERVER_CHALLENGE was
hardcoded to 0x11..0x88 across the fleet, which would let a scanner
fingerprint every DECNET decky by its NTLM challenge. Both SMB and
RDP now derive the 8-byte challenge from
instance_seed.random_bytes(8, "ntlm_challenge"), giving each decky a
deterministic-but-distinct value. SMB Dockerfile gets the
instance_seed.py copy too (was synced into the build context but not
COPYed into the image).

- decnet/services/rdp.py: optional service_cfg.nla bool flips
  RDP_ENABLE_NLA in the compose env.
- decnet/templates/rdp/Dockerfile + entrypoint.sh: openssl install +
  per-decky cert generation gated on RDP_ENABLE_NLA.
- 9 NLA unit tests cover the DER reader/builder, _handle_nla round-
  trip with Type 1 / Type 3, oversized-DER rejection, and per-
  NODE_NAME challenge divergence.
- DEBT.md: DEBT-040 closed; full TS_INFO_PACKET capture documented as
  a follow-up if attacker telemetry justifies it.
2026-04-25 07:42:52 -04:00

32 lines
1.1 KiB
Python

from pathlib import Path
from decnet.services.base import BaseService
TEMPLATES_DIR = Path(__file__).parent.parent / "templates" / "rdp"
class RDPService(BaseService):
name = "rdp"
ports = [3389]
default_image = "build"
def compose_fragment(self, decky_name: str, log_target: str | None = None, service_cfg: dict | None = None) -> dict:
fragment: dict = {
"build": {"context": str(TEMPLATES_DIR)},
"container_name": f"{decky_name}-rdp",
"restart": "unless-stopped",
"environment": {
"NODE_NAME": decky_name,
},
}
if log_target:
fragment["environment"]["LOG_TARGET"] = log_target
# Opt into the CredSSP / NLA capture path. Off by default — basic
# X.224 cookie capture is sufficient for most attacker traffic and
# avoids the openssl cert-gen overhead at container start.
if service_cfg and service_cfg.get("nla"):
fragment["environment"]["RDP_ENABLE_NLA"] = "true"
return fragment
def dockerfile_context(self) -> Path | None:
return TEMPLATES_DIR