🔒 Replace unsafe preexec_fn with start_new_session in audit.py

PR_DESCRIPTION.md

@@ -0,0 +1,10 @@
+# 🔒 Security Fix: Replace unsafe `preexec_fn` with `start_new_session`
+
+🎯 **What:**
+Replaced `preexec_fn=os.setsid` with `start_new_session=True` in `subprocess.Popen` within `commando/core/audit.py`.
+
+⚠️ **Risk:**
+Using `preexec_fn` in Python can lead to severe security and stability issues in multi-threaded applications. Specifically, if a thread holds a lock or forks concurrently, running an arbitrary callable via `preexec_fn` just before `exec()` can cause the child process to deadlock, potentially leading to denial of service or unexpected program crashes. This is a well-documented risk in the Python standard library.
+
+🛡️ **Solution:**
+Python 3.2+ introduced the `start_new_session` parameter to `subprocess.Popen` specifically to handle the common use case of running `os.setsid` safely. By switching to `start_new_session=True`, the child process continues to start in a new process group without risking deadlocks from concurrent threading operations, ensuring safe and reliable dynamic auditing (e.g., via `strace`).

commando/core/audit.py

@@ -74,9 +74,13 @@ def search_command(
                     execute_strace = False
                 else:
                     try:
-                        ans = input(
-                            f"{YELLOW}Warning: '{base_command}' is a custom import. Append '--help' for kinetic audit? (y/N): {RESET}"
-                        ).strip().lower()
+                        ans = (
+                            input(
+                                f"{YELLOW}Warning: '{base_command}' is a custom import. Append '--help' for kinetic audit? (y/N): {RESET}"
+                            )
+                            .strip()
+                            .lower()
+                        )
                     except (EOFError, KeyboardInterrupt):
                         ans = "n"
 
@@ -98,7 +102,7 @@ def search_command(
                     stdout=subprocess.PIPE,
                     stderr=subprocess.PIPE,
                     text=True,
-                    preexec_fn=os.setsid,
+                    start_new_session=True,
                 )
 
                 try: