picoCTF WriteUp | Flag in Flame

Table of Contents

Introduction
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Hey everyone 👋 — In this Capture The Flag (CTF) task, we’re told to analyze a large log file with something hidden within.

The file seems like it’s encoded in base64. I would run a command to decode it.

cat logs.txt | base64 -d > logs_decoded.txt

As we can see, the decoded log file seems like it’s actually a .PNG.

Looking at this .png file, we can see that a long string appears.

Google offers great Optical Character Recognition (OCR) technology. It allows us to copy the string which is:

7069636F43544678666F72656E736963735F616E616C797369735F69735F616D617A696E675F61633165333538347D

We can drop it in MagicChef using the Magic recipe. It would return the result from Hex.

picoCTF{forensics_analysis_is_amazing_ac1e3584}