An Italian Penguin

metactf

Task: a JPEG penguin image appeared to be a stego challenge, but normal metadata checks and outguess-style probing were misleading. Solution: interpret the Linux-themed hint as the GNU/Linux copypasta meme, use `GNU/Linux` as the passphrase, and extract the embedded payload with stegseek.

steghide jpeg stegseek dawgctf passphrase_stego hint_based_recon linux_meme

hint_interpretationpassphrase_derivationsteghide_payload_extractionfalse_positive_elimination

$ ls tags/ techniques/

steghide jpeg stegseek dawgctf passphrase_stego hint_based_recon linux_meme

hint_interpretationpassphrase_derivationsteghide_payload_extractionfalse_positive_elimination

$ cat /etc/rate-limit

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An Italian Penguin — metactf

Description

Original organizer description was not preserved locally.

Available hint: Hint 1: Search up Linux (To make a duplicate + Spaghetti is a type of what?)

English summary: the task provides a JPEG image named Penguin_Steg.jpg. The goal is to identify the correct stego path, derive the passphrase from the hint, extract the hidden payload, and recover the flag.

Analysis

The image was first treated as a standard JPEG stego target. Basic recon and extraction attempts did not immediately help:

EXIF, strings, and appended-data checks were clean.
stegdetect reported outguess(old)(***), but this turned out to be a false positive.
Clean reference images from the same penguin image family produced the same misleading outguess hit.
Multiple OutGuess candidate keys only produced garbage and wasted time.

The useful pivot came from identifying the picture itself. Penguin_Steg.jpg matches the well-known ccpenguin image associated with the history of Tux and Linux mascot lore. That made the hint much more meaningful:

duplicate → copy
spaghetti is a type of → pasta
Linux + copy + pasta → Linux copypasta

The most recognizable Linux copypasta is the GNU/Linux meme, so the correct passphrase is:

GNU/Linux

Once that interpretation was tried, extraction succeeded immediately.

Solution

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