Information Picogym Writeups

Files can always be changed in a secret way. Can you find the flag?

We were given the file cat.jpg. There’s something called a metadata on some images. Metadata stores basic information about the images. Such as author, time when the picture was taken, color profiles, and many more.

To view the metadata of an images, you can use a tool called exiftool. To install it on Ubuntu or other Debian based system you can use the command: sudo apt install exiftool Or if you are on a arch based system you can use the command: sudo pacman -S perl-image-exiftool Alternatively you can use an online tool to view metadatas.

To view a file’s metadata use the command: exiftool {filename}

After doing the command (note that you need to be on the same directory as the image, use cd to change directory) exiftool cat.jpg i saw something interesting. The lisence information is weird.

License                         : cGljb0NURnt0aGVfbTN0YWRhdGFfMXNfbW9kaWZpZWR9

I tried using online tools to identify it. It was identified as base64. https://www.dcode.fr/cipher-identifier decoded it, and got the flag.

picoCTF{the_m3tadata_1s_modified}