diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 0000000..8e6b540
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2024-07-03 - Windows File Launch Command Injection
+**Vulnerability:** `subprocess.call(['start', filename], shell=True)` was used to open files on Windows, creating a command injection risk even with `os.path.isfile()` checks, as legal filenames can contain shell metacharacters (`&`, `^`).
+**Learning:** Using `shell=True` with `start` on user-controlled or external paths is inherently unsafe on Windows because the shell parses metacharacters before the application opens the file.
+**Prevention:** Always use `os.startfile(filename)` for opening files natively on Windows, bypassing the shell entirely.
diff --git a/libs/utility_manager.py b/libs/utility_manager.py
index e62d1a5..95de28f 100644
--- a/libs/utility_manager.py
+++ b/libs/utility_manager.py
@@ -43,7 +43,7 @@ def _open_resource_file(self, filename):
 		try:
 			if os.path.isfile(filename):
 				if platform.system() == "Windows":
-					subprocess.call(['start', filename], shell=True)
+					os.startfile(filename)
 				elif platform.system() == "Darwin":
 					subprocess.call(['open', filename])
 				elif platform.system() == "Linux":