Hack The Box - HTB Autopilot Writeup - Insane - Weekly - october 17th, 2026

October 17, 2026

Target: ( mail.autopilot.htb, Grommunio Linux edge) · Attacker: (tun0) Domain: autopilot.htb · Internal: MAIL MAIL, DC01 DC01, WS02 WS02 OS: Linux (Grommunio) edge in front of a Windows Server 2025 AD · Difficulty: Insane Given foothold: deborah.hernandez: Flags user.txt (on the MAIL host, /root/user.txt ): [REDACTED-USER-FLAG] root.txt (on DC01, C:\Users\Administrator\Desktop\root.txt ): [REDACTED-ROOT-FLAG] 0. Environment setup 0.1 VPN path-MTU black hole (fix first, or large requests hang) This chain pushes big bodies (WebDAV PUTs, a multipart EML import, a 7 MB agent downloa…