diff --git a/app/api/query.py b/app/api/query.py
index 040385f..75efc5d 100644
--- a/app/api/query.py
+++ b/app/api/query.py
@@ -8,7 +8,7 @@ from pydantic import BaseModel
 import duckdb
 
 from app.auth.dependencies import get_current_user, _get_db
-from src.db import get_analytics_db
+from src.db import get_analytics_db_readonly
 from src.rbac import get_accessible_tables
 
 router = APIRouter(prefix="/api/query", tags=["query"])
@@ -43,6 +43,7 @@ async def execute_query(
         # File access functions
         "read_csv", "read_json", "read_parquet(", "read_text",
         "write_csv", "write_parquet",
+        "read_blob", "glob(", "read_ndjson", "'/", '"/',
         # Multiple statements
         ";",
     ]
@@ -55,7 +56,7 @@ async def execute_query(
     # Get allowed tables for this user
     allowed = get_accessible_tables(user, conn)
 
-    analytics = get_analytics_db()
+    analytics = get_analytics_db_readonly()
     try:
         if allowed is not None:  # None = admin, sees all
             # Get all views in analytics DB
diff --git a/app/api/scripts.py b/app/api/scripts.py
index 66ba56f..10cf0fa 100644
--- a/app/api/scripts.py
+++ b/app/api/scripts.py
@@ -143,6 +143,30 @@ def _execute_script(source: str, name: str) -> dict:
         "delattr(",
         "breakpoint(",
     ]
+    import ast
+
+    BLOCKED_MODULES = {"os", "sys", "subprocess", "shutil", "ctypes", "importlib", "socket",
+                       "requests", "urllib", "http", "signal", "pathlib", "builtins"}
+    BLOCKED_FUNCTIONS = {"exec", "eval", "compile", "open", "globals", "locals",
+                         "getattr", "setattr", "delattr", "breakpoint", "__import__"}
+
+    try:
+        tree = ast.parse(source)
+    except SyntaxError as e:
+        raise HTTPException(status_code=400, detail=f"Script syntax error: {e}")
+
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name.split(".")[0] in BLOCKED_MODULES:
+                    raise HTTPException(status_code=400, detail=f"Blocked import: {alias.name}")
+        elif isinstance(node, ast.ImportFrom):
+            if node.module and node.module.split(".")[0] in BLOCKED_MODULES:
+                raise HTTPException(status_code=400, detail=f"Blocked import: {node.module}")
+        elif isinstance(node, ast.Call):
+            if isinstance(node.func, ast.Name) and node.func.id in BLOCKED_FUNCTIONS:
+                raise HTTPException(status_code=400, detail=f"Blocked function: {node.func.id}")
+
     source_lower = source.lower()
     for pattern in blocked_patterns:
         if pattern.lower() in source_lower:
diff --git a/app/api/upload.py b/app/api/upload.py
index 609f800..b927dbf 100644
--- a/app/api/upload.py
+++ b/app/api/upload.py
@@ -4,6 +4,7 @@ import os
 import uuid
 from datetime import datetime, timezone
 from pathlib import Path
+from pathlib import Path as _Path
 
 from fastapi import APIRouter, Depends, HTTPException, UploadFile, File
 from pydantic import BaseModel
@@ -27,7 +28,10 @@ async def upload_session(
     sessions_dir = _get_data_dir() / "user_sessions" / user_id
     sessions_dir.mkdir(parents=True, exist_ok=True)
 
-    filename = file.filename or f"session_{uuid.uuid4().hex[:8]}.jsonl"
+    raw_name = file.filename or f"session_{uuid.uuid4().hex[:8]}.jsonl"
+    filename = _Path(raw_name).name  # Strips directory traversal components
+    if not filename or filename.startswith("."):
+        filename = f"upload_{uuid.uuid4().hex[:8]}"
     target = sessions_dir / filename
     content = await file.read()
     target.write_bytes(content)
@@ -44,7 +48,10 @@ async def upload_artifact(
     artifacts_dir = _get_data_dir() / "user_artifacts" / user_id
     artifacts_dir.mkdir(parents=True, exist_ok=True)
 
-    filename = file.filename or f"artifact_{uuid.uuid4().hex[:8]}"
+    raw_name = file.filename or f"artifact_{uuid.uuid4().hex[:8]}"
+    filename = _Path(raw_name).name  # Strips directory traversal components
+    if not filename or filename.startswith("."):
+        filename = f"upload_{uuid.uuid4().hex[:8]}"
     target = artifacts_dir / filename
     content = await file.read()
     target.write_bytes(content)
diff --git a/src/db.py b/src/db.py
index a54bfaa..27d60f1 100644
--- a/src/db.py
+++ b/src/db.py
@@ -212,6 +212,20 @@ def get_analytics_db() -> duckdb.DuckDBPyConnection:
     return duckdb.connect(str(db_path))
 
 
+def get_analytics_db_readonly() -> duckdb.DuckDBPyConnection:
+    """Read-only connection to analytics DB. Blocks writes and external access."""
+    db_path = _get_data_dir() / "analytics" / "server.duckdb"
+    if not db_path.exists():
+        db_path.parent.mkdir(parents=True, exist_ok=True)
+        return duckdb.connect(str(db_path), read_only=False)  # Can't open read-only if new
+    conn = duckdb.connect(str(db_path), read_only=True)
+    try:
+        conn.execute("SET enable_external_access = false")
+    except Exception:
+        pass  # Older DuckDB may not support this
+    return conn
+
+
 _V1_TO_V2_MIGRATIONS = [
     "ALTER TABLE table_registry ADD COLUMN IF NOT EXISTS source_type VARCHAR",
     "ALTER TABLE table_registry ADD COLUMN IF NOT EXISTS bucket VARCHAR",
diff --git a/tests/test_api_scripts.py b/tests/test_api_scripts.py
index b9dcae7..2bdeaba 100644
--- a/tests/test_api_scripts.py
+++ b/tests/test_api_scripts.py
@@ -75,7 +75,8 @@ class TestScriptsAPI:
             "source": "import subprocess; subprocess.run(['ls'])", "name": "bad",
         }, headers=headers)
         assert resp.status_code == 400
-        assert "disallowed" in resp.json()["detail"]
+        detail = resp.json()["detail"]
+        assert "disallowed" in detail or "Blocked" in detail
 
     def test_deploy_run_undeploy(self, client):
         c, _, analyst_token = client