Learn Hacking by Actually Hacking

Difficulty

Beginner

Vuln class

Linux CLI

Steps

// Objective

Navigate the Linux filesystem using the terminal to locate and read a hidden flag file.

// Tools required

bashlscdcatfind

// Step-by-step walkthrough

Explore your starting directory

When you connect, you land in the home directory. Start by listing all files — including hidden ones. Files prefixed with a dot are hidden from a standard ls.

Command / Input

ls -la

Output

total 32 drwxr-xr-x 1 root root 4096 Apr 8 10:00 . drwxr-xr-x 1 root root 4096 Apr 8 10:00 .. -rw-r--r-- 1 root root 220 Apr 8 10:00 .bash_logout drwxr-xr-x 1 root root 4096 Apr 8 10:00 .config drwxr-xr-x 1 root root 4096 Apr 8 10:00 missions

Navigate into the missions directory

The missions/ directory is where the challenges live. Move into it and list its contents.

Command / Input

cd missions && ls -la

Output

drwxr-xr-x 1 root root 4096 Apr 8 10:00 . drwxr-xr-x 1 root root 4096 Apr 8 10:00 .. drwxr-xr-x 1 root root 4096 Apr 8 10:00 briefing -rw-r--r-- 1 root root 128 Apr 8 10:00 README.txt

Read the README

Always read any README or instructions file first. It tells you what you're looking for.

Command / Input

cat README.txt

Output

Your mission: locate the flag hidden somewhere in this system. It begins with HackrGG{ and ends with }. Use find, ls, and cat to track it down.

Search the briefing directory

Go deeper into the briefing folder. Flags are often buried in nested directories.

Command / Input

cd briefing && ls -la

Output

drwxr-xr-x 1 root root 4096 Apr 8 10:00 . drwxr-xr-x 1 root root 4096 Apr 8 10:00 .. drwxr-xr-x 1 root root 4096 Apr 8 10:00 .hidden -rw-r--r-- 1 root root 42 Apr 8 10:00 notes.txt

Check the hidden directory

A hidden .hidden directory — exactly what you're looking for. Hidden directories need -la to show up.

Command / Input

cd .hidden && ls && cat flag.txt

Output

flag.txt HackrGG{y0u_n4v1g4t3d_th3_t3rm1n4l}

⚑ The flag was in a hidden directory inside a nested folder. This mirrors how attackers hide artifacts on compromised systems.

// Flag

Flag value

HackrGG{y0u_n4v1g4t3d_th3_t3rm1n4l}

Submit this flag in the course lab to mark the task complete.

Linux CLI Sandbox