PicoCTF Writeup – So Meta

Information: 

 

CTF Name: PicoCTF

CTF Challenge: So Meta

Challenge Category: Forensics

Challenge Points: 150

PicoCTF 2019.

 

# Challenge Description: 

 
Find the flag in this picture.
 
 
Relevant hint: What does meta mean in the context of files? Ever heard of metadata?

Writeup 

 
In this challenge, the word picture in the descriptions holds a link to an image. Upon clicking on it an image was downloaded. By looking at the image nothing seemed relevant to help me solve this. 
 
I decided to take into account the hints provided and I thought about analyzing the metadata of this file.
 
To do so I open my Linux terminal, because I prefer to use Linux forensic tools. Afterward, I google around a little trying to find a good tool to analyze the metadata of files in Linux. 
 
I stumbled across this site in which they present the tool ExifTool. This tool does exactly what we want, it extracts metadata from several files, like images, which is our particular case.
I went to back to the Linux termianl and installed this tool by using the command:
mregra on Cyber ~$ sudo apt install exiftool -y

Once it was installed I decided to try to use it, to do so I simple did this command:  

mregra on Cyber ~$ exiftool pico_img.png

And this was the output:  

As you can see, under the tag Artist we have the flag, picoCTF{…}.  

And the flag is:

Show flag
picoCTF{s0_m3ta_d8944929}

The image source can be found here.

Thank you very much for reading!

Cheers,

MRegra

One Reply to “PicoCTF Writeup – So Meta”

  1. I’m not positive where you’re getting your information, but great topic.
    I needs to spend a while finding out more or figuring out
    more. Thanks for excellent info I used to be on the lookout for this information for my
    mission.

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