feat(backend): c2 crypto + config CRUD + adapter scaffolding (sprint 8 M1)

- Add Fernet crypto service (MIMIC_ENCRYPTION_KEY env, C2Disabled on absent key)
- Add Alembic migration 0006: c2_config + c2_task tables with cascade FKs
- Add C2Config and C2Task SQLAlchemy models
- Add C2Adapter ABC with dataclasses (C2Health, C2Callback, C2TaskStatus, C2TaskPage)
- Add FakeAdapter (deterministic in-memory, MIMIC_C2_ADAPTER=fake)
- Add MythicAdapter scaffold: test_connection() live, M2+ raise NotImplementedError
- Add decode_response_text() helper for base64/binary Mythic responses
- Add GET/PUT/DELETE/POST-test /api/engagements/<id>/c2-config endpoints
- RBAC: admin+redteam OK, SOC 403; 503 guard when encryption key absent
- Token never returned in API responses; stored Fernet-encrypted only
- 42 new tests (300 total, 258 baseline preserved green)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/__init__.py

@@ -1,8 +1,9 @@
 """API blueprints."""
 from backend.app.api.auth import auth_bp
+from backend.app.api.c2 import c2_bp
 from backend.app.api.engagements import engagements_bp
 from backend.app.api.simulations import simulations_bp
 from backend.app.api.templates import templates_bp
 from backend.app.api.users import users_bp
 
-__all__ = ["auth_bp", "users_bp", "engagements_bp", "simulations_bp", "templates_bp"]
+__all__ = ["auth_bp", "c2_bp", "users_bp", "engagements_bp", "simulations_bp", "templates_bp"]

backend/app/api/c2.py

@@ -0,0 +1,156 @@
+"""C2 config endpoints for engagements.
+
+All four endpoints:
+- Require admin or redteam role (SOC → 403).
+- Return 503 when MIMIC_ENCRYPTION_KEY is not set.
+- Never include the cleartext API token in any response.
+"""
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from flask import Blueprint, jsonify, request
+
+from backend.app.auth import role_required
+from backend.app.extensions import db
+from backend.app.models import Engagement
+from backend.app.models.c2_config import C2Config
+from backend.app.services.c2.factory import get_adapter
+from backend.app.services.crypto import C2Disabled, decrypt, encrypt
+
+c2_bp = Blueprint("c2", __name__, url_prefix="/api/engagements")
+
+_503_BODY = {"error": "C2 disabled: MIMIC_ENCRYPTION_KEY not set"}
+
+
+def _crypto_guard():
+    """Return a 503 Response when crypto key is absent, else None."""
+    try:
+        # Attempt a dummy operation to test key availability.
+        encrypt("probe")
+        return None
+    except C2Disabled:
+        return jsonify(_503_BODY), 503
+
+
+@c2_bp.get("/<int:eid>/c2-config")
+@role_required("admin", "redteam")
+def get_c2_config(eid: int):
+    guard = _crypto_guard()
+    if guard is not None:
+        return guard
+
+    engagement = db.session.get(Engagement, eid)
+    if engagement is None:
+        return jsonify({"error": "Engagement not found"}), 404
+
+    cfg: C2Config | None = engagement.c2_config
+    if cfg is None:
+        return jsonify({"error": "C2 config not found"}), 404
+
+    return jsonify({
+        "has_token": bool(cfg.api_token_encrypted),
+        "url": cfg.url,
+        "verify_tls": cfg.verify_tls,
+    }), 200
+
+
+@c2_bp.put("/<int:eid>/c2-config")
+@role_required("admin", "redteam")
+def upsert_c2_config(eid: int):
+    guard = _crypto_guard()
+    if guard is not None:
+        return guard
+
+    engagement = db.session.get(Engagement, eid)
+    if engagement is None:
+        return jsonify({"error": "Engagement not found"}), 404
+
+    data = request.get_json(silent=True) or {}
+    url = (data.get("url") or "").strip()
+    if not url:
+        return jsonify({"error": "url is required"}), 400
+
+    verify_tls = data.get("verify_tls", True)
+    if not isinstance(verify_tls, bool):
+        return jsonify({"error": "verify_tls must be a boolean"}), 400
+
+    cfg: C2Config | None = engagement.c2_config
+
+    if cfg is None:
+        # New row — api_token is required on creation.
+        raw_token = data.get("api_token") or ""
+        if not raw_token:
+            return jsonify({"error": "api_token is required when creating a config"}), 400
+        encrypted = encrypt(raw_token)
+        cfg = C2Config(
+            engagement_id=eid,
+            url=url,
+            api_token_encrypted=encrypted,
+            verify_tls=verify_tls,
+        )
+        db.session.add(cfg)
+    else:
+        # Update — omitting api_token keeps the existing ciphertext.
+        cfg.url = url
+        cfg.verify_tls = verify_tls
+        cfg.updated_at = datetime.now(UTC)
+        raw_token = data.get("api_token") or ""
+        if raw_token:
+            cfg.api_token_encrypted = encrypt(raw_token)
+
+    db.session.commit()
+    return jsonify({
+        "has_token": True,
+        "url": cfg.url,
+        "verify_tls": cfg.verify_tls,
+    }), 200
+
+
+@c2_bp.delete("/<int:eid>/c2-config")
+@role_required("admin", "redteam")
+def delete_c2_config(eid: int):
+    guard = _crypto_guard()
+    if guard is not None:
+        return guard
+
+    engagement = db.session.get(Engagement, eid)
+    if engagement is None:
+        return jsonify({"error": "Engagement not found"}), 404
+
+    cfg: C2Config | None = engagement.c2_config
+    if cfg is None:
+        return jsonify({"error": "C2 config not found"}), 404
+
+    db.session.delete(cfg)
+    db.session.commit()
+    return "", 204
+
+
+@c2_bp.post("/<int:eid>/c2-config/test")
+@role_required("admin", "redteam")
+def test_c2_config(eid: int):
+    guard = _crypto_guard()
+    if guard is not None:
+        return guard
+
+    engagement = db.session.get(Engagement, eid)
+    if engagement is None:
+        return jsonify({"error": "Engagement not found"}), 404
+
+    cfg: C2Config | None = engagement.c2_config
+    if cfg is None:
+        return jsonify({"error": "C2 config not found"}), 404
+
+    try:
+        api_token = decrypt(cfg.api_token_encrypted)
+    except ValueError:
+        return jsonify({"ok": False, "error": "Stored token is corrupt"}), 200
+
+    adapter = get_adapter(
+        url=cfg.url,
+        api_token=api_token,
+        verify_tls=cfg.verify_tls,
+    )
+    health = adapter.test_connection()
+    return jsonify({"ok": health.ok, "error": health.error}), 200