Same Flag for Challange 1 and 7

[patrickvanvilsteren]

Good morining!

I ran into an issue where the Flags for Challenges 1 and 7 are the same.
Which causes errors on verifying.
I don't want to spool anything in here. But if you have any questions, please let me know.

Kind reegards,

Patrick van Vilsteren

[github-actions]

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[patrickvanvilsteren]

• Go to "ctf_challenges"
• list the hidden files with a certain command.
• Open de hidden file and note the flag. (I couldn't verify this flag neither)
• Open the encoded_flag.txt file. Decode if needed with a certain command.
• Check the Flag inside the encoded_flag.txt
• These are the same

[patrickvanvilsteren]

I see that the flag in 1 and 7 belong to challenge 10

[madebygps]

Thanks for reporting! The flags for challenges 1 and 7 are generated with different base strings (hidden_files vs decode_master).

What you may be seeing is the Challenge 10 broadcast — there's a background service that monitors ctf_challenges/ for new files, and when one is created it broadcasts the Challenge 10 flag via wall to your terminal. That flag showing up could be confused with the flag you're working on.

Could you share:

Which cloud provider (AWS/Azure/GCP)?
The exact flag values you found for challenges 1 and 7 (redact the suffix)?
The exact verify commands you ran and their output?

[patrickvanvilsteren]

Thanks for your reply!

• I am using Azure as my provider
• The flags CTF{net_copy_xxxxxx} for both of them
• verify 1 [FLAG]
• verify 7 [FLAG]
  Reply:
  ✗ Incorrect flag. Try again!
  Flags Found: 9/18

[madebygps]

@patrickvanvilsteren Can you confirm you have gone through all the learning material we outlined to be done prior to the labs please.

Can you also share the commands you are using to solve each challenge please.

[patrickvanvilsteren]

yes, I read all 9 chapters of Linux for Hackers.
Challenge 1:
ls -a
open hidden file

Challenge 7:

• I used "man base64"
• Then I used base64 -d [file] for decoding

[madebygps]

@patrickvanvilsteren try this:

Challenge 1: cat ~/ctf_challenges/.hidden_flag — the flag starts with CTF{hidden_files_...}

Challenge 7: cat ~/ctf_challenges/encoded_flag.txt | base64 -d | base64 -d — the file is double-encoded, so you need to decode twice. The flag starts with CTF{decode_master_...}

[patrickvanvilsteren]

yeah that works... But why not when i open the file...?
btw, you can delete your thread for spoolers :)

[madebygps]

I'm assuming by "opening" the file you mean using an editor like vi or nano to read it? The goal of these labs is to teach you efficient use of Linux commands, for reading files you should use cat, tail, head, etc., not opening a file in an editor unless you plan to edit it.

When you opened the file in an editor, it created a temporary swap file in the same directory, which triggered Challenge 10's background monitor and broadcast that flag to your terminal. That's why you kept seeing the same CTF{net_copy_...} flag everywhere. The challenge descriptions and hints point you toward the right commands — try verify hint [num] if you get stuck.