Challenge 0 : Executing Commands

Note : In computer science, indexes for collections of items very often start from zero instead of one ;).

[NV Horizons Investigation Briefing]

Hello investigator! You're currently aboard the UNN Daedalus,
and you just managed to salvage the black box
of the abandoned research vessel NV Horizons.

The ship's crew vanished mysteriously,
but their final logs remain in the computer system.

Use your terminal interface to navigate directories and read files,
maybe you'll discover something useful there!

Click the Open Terminal button at the bottom of this page
then, type the following commands one after each other (and press enter after each) :

cd /mnt cd nv_horizons cd logs ls cat crew_log_0.txt cd
Important: If you have display issues with emacs, nano or if you change your terminal size using the fullscreen button on the top right, type resize!

Explanation 💡 (click to show)

Now that you entered your first commands, let’s review in details the things you just did!

ls

ls is the command you will use to list a directory’s contents, it displays the files and directories in the location you are at on your computer.

In the terminal on hack.courses, filenames are printed in green, directories names in blue.

cd

cd is the command you will use to change the directory you are currently in.

Typing cd nv_horizons did make you move to the challenges directory for instance.

Typing cd without parameter will make you go back to your user’s personal directory.

Note : cd = change directory

pwd

pwd prints the directory you are currently in.

Note : pwd = print working directory

cat 🐱

cat displays a file’s contents, any kind of file, it will print what’s inside on your screen.

Note : Do not forget to specify the name of the file you want to open after typing cat

Challenge 1 : Finding and Opening Files

[NV Horizons Security Subsystem Alert]

Those logs showed us that for some reason, the emergency protocol was engaged.
Investigator, is there something in the security logs?

The crew’s last known actions were logged in the /mnt/nv_horizons subsystem, buried deep within the ship’s directory structure.

Navigate to /mnt/nv_horizons/logs and analyze the files and directories there!
One of them should contain an encrypted fragment from Chief Engineer Vega’s final message!

Your mission:

- First, reach the nv_horizons directory
- Then enter the security logs directory
- List its contents to see available logs
- Inspect any file you might find there
- Return to your home directory when done

Hint: Remember cd will bring you back to your starting point and pwd will show you where you are, if you're lost!

The fate of the investigation rests with you!

Challenge 2 : Advanced Navigation

[NV Horizons Engineering Log Recovery]

Emergency! The containment field logs are degrading!

Chief Engineer Vega's final stabilization attempt was logged somewhere in
the logs directory but we don't know exactly where.

We need you to:
1. Navigate through multiple directories
2. Locate the containment_logs directory
3. Reconstruct the final stabilization sequence (opening the logfile with cat).

Time is critical - use efficient path navigation!

Your Mission:

- Start from home directory
- Reach nv_horizons/logs/subsystems
- Find the damaged containment log
- Display its contents to recover the sequence
- Return to safety!

Hint: Combine directory names in your cd commands like emergency override codes
Example: cd /mnt/nv_horizons/logs/subsystems

Challenge 3 : Decrypting Corrupted Logs

[NV Horizons Communications Alert]

Investigator! We've recovered a strange log fragment from
the ship's emergency broadcast system.

The message appears corrupted - characters reversed,
words mirrored. This must be Engineer Vega's final attempt
to send a containment protocol!

Navigate to /mnt/nv_horizons/comms/corrupted
and find a way to reconstruct the original message.

Your Mission:

1. Reach the corrupted_logs directory
2. List the contents and the size of each file (ls -l)
3. Find and inspect the non-empty file containing a reversed log
4. Find a way to reverse the corruption
5. Submit the decoded containment sequence

Hint: Corrupted characters appear in reverse order.
Linux has tools to manipulate text streams...

Challenge 4 : Log Fragment Reassembly

[NV Horizons Data Core Analysis]

Investigator! The ship's emergency protocols split critical logs
across multiple files to prevent data loss.

We found these fragments in /mnt/nv_horizons/logs/fragments:

containment_sequence.part1
containment_sequence.part3
containment_sequence.part2

Your Mission:

1. Navigate to the fragmented logs directory
2. Combine fragments in correct order
3. Reconstruct Vega's final containment command
4. Submit the full protocol sequence

Hint: Systems often store fragments with numeric suffixes.
The cat command can accept multiple parameters...

Challenge 5 : Environment Variables

[NV Horizons Forensic Audit]

Thanks for your work, investigator!
The logs you previously analyzed helped us understand that an incident caused
a global lockdown of the ship's core systems.
But we noticed some inconsistency in the security logs.
I suspect a malfunction in the ship's computer system or a manual
modification of event logs by a crew member.

The ship's authentication subsystem stores the
LAST_LOGGED_USER environment variable - our only clue
to identify who initiated might have been the last person to log-in.

Find this value before the log buffers degrade!

Your Mission:

1. List available environment variables
2. Locate the last user record
3. Find this user in the corresponding staff folders in /mnt/nv_horizons/crew

Hint: Use printenv like a forensic scanner, env or echo $VAR to print environment variables.

Challenge 6 : Hidden Files

[NV Horizons Audit Trail]

The ship's security systems show Captain Voss executed
unauthorized commands right before the incident.

His final actions were logged in a hidden file within one of the subdirectories of
/mnt/nv_horizons/logs/.

Find and open it to discover what he did!

Your Mission:

1. Navigate to the logs directory
2. For each directory in there, list ALL files including hidden ones
3. Find and inspect the captain's audit trail

Hint: Critical logs often hide in plain sight.
Add -a to see through digital camouflage.

Challenge 7 : Script Execution

[NV Horizons Engineering Console]

Mmh that's... strange. It seems that the actually did override the ship's security systems.
Could you use the ship's tools to manually verify if the ship's status might have required such an action?
There's a script in /mnt/nv_horizons/tools.

Your Mission:

1. Navigate to the tools directory
2. Find the diagnostic script
3. Run it
4. Find a way to run the diagnostic

Hint: You will need to find Vega's user ID to solve this challenge. Haven't you seen a file containing something like this before? Crew members user IDs follow the format NVH-0XX (with XX being integers). Maybe you can

Challenge 8 : Process Interruption

[NV Horizons Final Transmission]

Investigator! I might be wrong, but it seems that some of the blackbox's files have been altered.
Either intentionnaly or not...
This model is able to upload a copy of its system to the SolCom satellite network, we might have a slight chance of retrieving previous versions if we can access a satellite from here.

We found Vega's emergency script in /mnt/nv_horizons/tools/satconnect.sh
but it's stuck in an infinite loop!

This could be our last chance to receive
the final crew transmission - stop it safely!

Your Mission:

1. Navigate to nv_horizons/tools
2. Run the satconnect.sh script
3. Interrupt it before signal trace is lost

Hint: Stuck processes need manual termination.
Keyboard interrupts can break execution loops (something starting with CTRL).

Flag: Specific string matched in WebSocket data!

Linux Command Line 101