Nightmare

Verified writeups for the Nightmare machine of Hack The Box

Nightmare

$ tldr OpenSSH SFTP misconfig → command injection → Ubuntu Xenial kernel

·	·
Operating system	Linux
Difficulty	Insane
Vector	Web
IP	10.10.10.66
Retirement date	—
Skills	HTML Injection XSS Injection SQL Injection (SQLI) - Error Based OpenSSH <= 6.6 SFTP misconfiguration universal exploit (RCE) Script Modification Binary Analysis [GHIDRA/Radare2] In-depth analysis with Radare2 [Tips and tricks] Command Injection - User Pivoting Ubuntu Xenial Privilege Escalation - Kernel Exploitation

Writeups

Language	Author	Format	Link
🇪🇸 ES	S4vitar	Vídeo	Open
🇬🇧 EN	IppSec	Vídeo	Open

Skill resources

Curated documentation for each technique listed in the Skills column above. Sources: HackTricks, GTFOBins, PortSwigger, etc.

Skill	Source	Link
OS Command Injection	PortSwigger	Open
SQL Injection	HackTricks	Open
SQL Injection	PortSwigger	Open
Port Forwarding / Pivoting	HackTricks	Open
Remote Code Execution (RCE)	HackTricks	Open
Cross-Site Scripting (XSS)	HackTricks	Open
Cross-Site Scripting (XSS)	PortSwigger	Open

Related skills worth mastering

Local File Inclusion (LFI) · Remote File Inclusion (RFI) · Shellshock (CVE-2014-6271) · Server-Side Request Forgery

If you liked this machine, try

• Holiday — Linux, Hard
• ScriptKiddie — Linux, Easy
• Union — Linux, Medium
• Toolbox — Windows, Easy
• Oz — Linux, Hard

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Comments & tips

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Last updated: 2026-07-13