Old Paper.

1. Initial recon#

Open the challenge URL in a browser:

https://challenges.tibeb.org/073bb21e-7bd9-4505-8e1c-a5288c114da4/

The visible page only says:

Tibeb · old-paper
The new archive is almost ready.

The hint says:

The festival archivist replaced the front page, but forgot that browsers keep reading past what they display.

That points toward HTML source code, especially comments or hidden elements.

2. View the page source#

In Parrot OS, you can use curl or the browser’s View Source.

Using curl:

curl -sL 'https://challenges.tibeb.org/073bb21e-7bd9-4505-8e1c-a5288c114da4/' -o oldpaper.html

Search the raw HTML:

grep -niE 'robots|staff|note|hidden|tibeb\{|<!--' oldpaper.html

Output reveals an HTML comment:

<!-- migration checklist: review robots.txt -->

So the next step is to check robots.txt.

3. Check robots.txt under the challenge path#

The HTML comment leads to a challenge-specific robots.txt file under the challenge prefix.

Fetch the challenge-specific robots.txt:

curl -sL 'https://challenges.tibeb.org/073bb21e-7bd9-4505-8e1c-a5288c114da4/robots.txt'

Output:

User-agent: *
Disallow: /staff/retired-note.txt

This tells us there is a hidden path:

/staff/retired-note.txt

4. Fetch the disallowed file#

In standard robots rules, a path beginning with / refers to the origin root. This challenge uses the nested robots file as a puzzle clue. The recorded solution tested the staff path under the challenge prefix and found the note there:

curl -sL 'https://challenges.tibeb.org/073bb21e-7bd9-4505-8e1c-a5288c114da4/staff/retired-note.txt'

Output:

Retired staff dispatch: tibeb{old_paper_632aa86068f902e8aaac}

5. Flag#

tibeb{old_paper_632aa86068f902e8aaac}

Key takeaway#

The challenge relied on two common web CTF tricks:

1. HTML comments are not displayed but are still readable in source.
2. robots.txt can leak hidden or disallowed paths.

The successful path is specific to this exercise, rather than a general rule for resolving robots directives. In the recorded requests:

https://challenges.tibeb.org/staff/retired-note.txt

returned 404, but:

https://challenges.tibeb.org/073bb21e-7bd9-4505-8e1c-a5288c114da4/staff/retired-note.txt

worked.