Secret of the Polyglot

Welcome back to the write-up series of picoCTF. Today we’ll see about the Secret of the Polyglot Challenge in Forensics Category

Challenge Name: Secret of the Polyglot

Category: Forensics Easy

Description: The Network Operations Center (NOC) of your local institution picked up a suspicious file, they’re getting conflicting information on what type of file it is. They’ve brought you in as an external expert to examine the file. Can you extract all the information from this strange file?

First of all we’ll see the challenge

Hint 1: This problem can be solved by just opening the file in different ways

We will first download the pdf file given, on opening the pdf file we can see the last part of the flag

Now we have to find the remaining part of the flag

First we will run file command on the downloaded file

As we can see that this is a PNG file, not a pdf file file so we must open it as a PNG file to reveal the first part of the flag

For that we just simply change the extension of the file from pdf to png

After renaming and opening the png file with eog we get the first part of the flag

picoCTF{f1u3n7

Now we will merge both the parts

picoCTF{f1u3n71n_pn9_&_pdf_249d05c0}

That’s it you found the flag!

Flag : picoCTF{f1u3n71n_pn9_&_pdf_249d05c0}

## Takeaway

A polyglot file is a single file that is valid in two or more different file formats or programming languages simultaneously, allowing it to be interpreted differently depending on the application that opens it