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niteCTF Boys

··370 words·2 mins·

Prompt #

The new Head of Crime Analytics is named - The Deep. The Deep addresses the Crime team and Cassandra brings cupcakes for the team. They fired most of the staff because of past tweets that were critical of Homelander. Homelander as paranoid as ever believes that the boys has yet another plan to take down Vought International. As one of the members from the few left behind it is upon your shoulders to crack down on the boys’ plan to take down Vought by looking into the suspicious GitHub user who goes by the name sk1nnywh1t3k1d or face Homelander’s wrath.

Solution #

GitHub #

  1. The GitHub profile can be found at https://github.com/sk1nnywh1t3k1d.
  2. This GitHub user has only one repository with only 2 commits at https://github.com/sk1nnywh1t3k1d/chat-app.
  3. The first commit added a file named chat.txt that was deleted on the second commit at https://github.com/sk1nnywh1t3k1d/chat-app/commit/d830e9b9a9cd531b2677bad94b4a08d7a539738b#diff-d341c91ed9aff89bf6ea2d5fa7b245307f745a1e9374328e47c79f1529be627a.
    • The commit also has author’s the email (hughiecampbell392@gmail.com), visible when viewing the verbose commit patch, by appending .patch to the commit URL.
  4. The chat.txt file mention the shortened URL https://bit.ly/voughtencrypted

WAV #

  1. The previously-mentioned shortened URL leads to an audio file download:

  2. When the audio file is shown in Audacity’s Spectrogram, the following text (thguovdne hsals drawrof yl tod tib) can be seen:

    Audacity’s Spectrogram showing text of a message

  3. By reversing the message, the shortened URL ( https://bit.ly/endvought) can be read:

    $ echo "thguovdne hsals drawrof yl tod tib" | rev
    bit dot ly forward slash endvought
    

PNG #

  1. The previously-mentioned shortened URL leads to an image file download:
  2. The shredded red text looks like an email address, but since the email address looks like the one found in the commit metadata, I didn’t un-shred the picture. During the event, I had not idea how to continue from here, with the email address in hand.

E-mail Address #

  1. I didn’t figure it out during the event, but once I had Hughie’s email address I could find his public Google calendar with the hyper link calendar.google.com/calendar/u/0/embed?src=hughiecampbell392@gmail.com.
    • Additional intelligence could be gathered about the email address using tools such as EPIEOS.
    • The Google ID of the email address could be gathered by initiating a Google Hangouts chat and inspecting the HTML at the recipient’s details.
  2. The only event during December 2022 has the flag niteCTF{v0ught_n33ds_t0_g0_d0wn}.
Omri Bornstein
Author
Omri Bornstein
Software Engineer, Gopher, TeXnician